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(A) SDS-PAGE of whole-cell proteins (lane 2) and hydrophobic (lane 3) and hydrophilic (lane 4) proteins of cultures of uniformly HAd Ϫ (lanes a) and HAd ϩ (lanes b) M. synoviae colonies. Lane 1 shows protein molecular mass markers. (B) Immunoblots of the whole-cell proteins of the same cultures probed with a pool of MAbs 50, 97, and 334 (lane 1), chicken anti- M. synoviae (lane 2), and rabbit anti-MSPA 1 (lane 3).
Source publication
Mycoplasma synoviae is a major pathogen of poultry, causing synovitis and respiratory infection. A cluster of 45- to 50-kDa membrane proteins is immunodominant in strain WVU-1853. Four distinct proteins were identified in this cluster by high-pressure liquid chromatography. Monoclonal antibodies and monospecific antisera against each established th...
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Background:
The bacterial pathogen Mycoplasma synoviae can cause subclinical respiratory disease, synovitis, airsacculitis and reproductive tract disease in poultry and is a major cause of economic loss worldwide. The M. synoviae strain MS-H was developed by chemical mutagenesis of an Australian isolate and has been used as a live attenuated vacci...
Mycoplasma gallisepticum (MS) and Mycoplasma synoviae (MS) are important avian pathogens and cause economic losses to the poultry industry. Molecular biology techniques are currently used for a rapid detection of these pathogens and the adoption of control measures of the diseases. The aim of this study was to develop and validate a technique for s...
A quantitative PCR (qPCR) able to differentiate between field M. synoviae and MS-H vaccine strain was developed, validated and evaluated. It was developed using nucleotide differences in the obg gene. Analytical specificity and sensitivity was assessed using DNA from 194 M. synoviae field samples, three different batches of MS-H vaccine and from 43...
Background
Mycoplasma synoviae causes infectious synovitis and respiratory diseases in chickens and turkeys and may lead to egg shell apex abnormalities in chickens; hence possesses high economic impact on the poultry industry. Control of the disease consists of eradication, vaccination or medication. The aim of the present study was to determine t...
Citations
... Additionally, lipoproteins with antigenic variability aid the bacterium in evading the host's immune system. One such lipoprotein is haemagglutinin, referred to as vlhA [4]. In other studies, a lipoprotein known as pMGA was identified with amino acids resembling those of vlhA and the research concluded that are the same lipoprotein [5]. ...
... The pMGA1.2 clonal gene from the MGS6 strain encodes a polypeptide variant that shares over 90 % similarity to vlhA [8]. Promoter regions identified as GAA have been reported in both vlhA and pMGA, supporting the notion that they represent the same gene [4,11]. The sequence M83178.1 has not been studied in field strains and since this sequence is reported to match with sequences of vlhA, it is not considered as specific for some mycoplasma species, although study of this sequence in field strains is convenient, since the haemagglutinin is involved in pathogenicity and antigenicity in vaccines against M. gallisepticum and Mycoplasma synoviae. ...
Mycoplasmosis, attributed to Mycoplasma gallisepticum , poses a significant challenge to poultry farming, leading to substantial economic losses and persistent infections within flocks. This bacterium harbours various surface proteins that are crucial for adhesion, transporter activity and evasion of the host immune response, facilitating its pathogenicity. One such key surface lipoprotein, referred to as pMGA or vlhA haemagglutinin, plays a pivotal role in adhesion processes. In this study, the clonal regions pMGA1.2 and pMGA1.3, as reported by Markham (M83178.1), were investigated to elucidate differences or similarities in the whole DNA sequences of M. gallisepticum field strains. The aim was to analyse sequence diversity within this region. Six internal primers were designed to amplify the target sequence, and isolates were obtained from both eggs and chickens sourced from laying hen flocks. Identification revealed 17 strains of M. gallisepticum and four strains of Mycoplasma synoviae , which were confirmed through the mgc2 and 16S rRNA genes, respectively. Positive and negative controls were established using the MGS6 and MSWUV1853 strains. Amplification results indicated a higher frequency of amplification proximal to the C-terminal region, with segments 4 (33.3 %) and 6 (27.8 %) being the most prevalent. Notably, none of the field strains exhibited the same amplification pattern as MGS6, and none of the strains characterized as M. synoviae amplified any primer set. Upon translation, the amino acid sequences from segments 4 and 6 were found to be compatible with conserved sequences within the Myco_haema protein domains of the genus Mycoplasma , specifically corresponding to Q7NAP3_MYCGA VlhA.3.04. The observed homology suggests a potential genetic transfer, while the variability identified in the pMGA or vlhA gene region of the field strains may have significant implications for protection against M. gallisepticum infection in chickens.
... The second stage entails the correctly binding of the microorganism-specific ligands to the relevant host cell receptors, primarily via the surface proteins (Razin and Jacobs, 1992). Variable lipoprotein hemagglutinin (vlhA), enolase, pyruvate dehydrogenase alpha (PdhA) and beta (PdhB) subunits, dihydrolipoamide dehydrogenase (PdhD), NADH oxidase and other surface proteins from M. synoviae have been identified to be involved in adhesion (Noormohammadi et al., 1997;Bao et al., 2014Bao et al., , 2021Hu et al., 2022;Qi et al., 2022). Additionally, most microorganisms bind to a range of host extracellular matrix (ECM) components, such as fibronectin (Fn), collagen, elastin, and laminin via interactions between microbial adhesins and host cell receptors (Chagnot et al., 2012). ...
... Attachment of mycoplasmas to host cells is a crucial step in colonization and subsequent infection, which is predominantly mediated by membrane proteins and lipoproteins Browning et al., 2011). Various membrane-associated proteins, incuding vlhA, enolase, PdhA and PdhB subunits, PdhD and NADH oxidase, are involved in M. synoviae cytadhesion (Noormohammadi et al., 1997;Bao et al., 2014Bao et al., , 2021Hu et al., 2022;Qi et al., 2022). Mycoplasma lipoproteins have been demonstrated to exert a variety of effects during infection and interaction with the hosts, including immunomodulatory, antigenic variation, transporter operation, and cytoadhesion (Athamna et al., 1997;Browning et al., 2011;Christodoulides et al., 2018). ...
... The fact that mycoplasmas cytadherence is a complex, multifactorial process involving numerous membrane proteins and cytoskeletal elements (Razin and Jacobs, 1992). In addition to LP78, other proteins have also been proven to contribute to the adhesion process of M. synoviae, such as vlhA, enolase, PdhA, PdhB, PdhD and NADH oxidase (Noormohammadi et al., 1997;Bao et al., 2014Bao et al., , 2021Hu et al., 2022;Qi et al., 2022). It has been established that vlhA facilitates M. synoviae attachment to sialylated receptors on host cells (May et al., 2014). ...
Mycoplasma synoviae ( M. synoviae ) is one of the major poultry pathogens causing infectious synovitis, airsacculitis, a high incidence of shell breakage, and egg production loss. However, the pathogenesis of M. synoviae remains unclear. Adhesion of mycoplasmas to host cells is a crucial step in infection and colonization. The purpose of this study was to determine the adhesive function of a putative P80 family lipoprotein (LP78) and evaluate its application in the detection of antibodies against M. synoviae . Recombinant LP78 (rLP78) was expressed in the supernatant component of Escherichia coli and mouse anti-rLP78 serum was prepared. Bioinformatic analysis and western blotting results revealed that LP78 was conservative among M. synoviae strains. It was distributed not only in the cytoplasm but also on the membrane of M. synoviae through western blotting and indirect immunofluorescence (IFA). The adherence of M. synoviae to DF-1 cells was significantly inhibited by mouse anti-rLP78 serum ( p < 0.01). IFA revealed that rLP78 adhered to DF-1 cells, and this adherence was prevented by mouse anti-rLP78 serum. Furthermore, rLP78 was found to bind to the DF-1 cells membrane proteins in a dose-dependent manner by enzyme-linked immunosorbent assay (ELISA). Screening of DF-1 cells membrane proteins by western blotting showed that proteins with molecular weight of 35–40 kDa and 55–70 kDa bound to rLP78. Moreover, rLP78 was identified to be a fibronectin/plasminogen binding protein. The sensitivity and specificity of rLP78-based iELISA were 85.7 and 94.1%, respectively. The maximum dilution of positive serum (HI titer, 1:128) detected via rLP78-based iELISA was 1:6,400, whereas that detected using a commercial ELISA kit was 1:12,800–1:25,600. Both rLP78-based iELISA and the commercial ELISA kit detected seroconversion after 7 days of challenge and immunization. No cross-reactivity with positive sera against other avian pathogens was observed in rLP78-based iELISA. Collectively, these results indicate that LP78 is a fibronectin/plasminogen-binding adhesion protein of M. synoviae and a potential diagnostic antigen. The present study will facilitate a better understanding of the pathogenesis of M. synoviae and the development of new diagnostic.
... NADH oxidase belongs to the largest group of enzyme oxidoreductases, which functions in catalyzing the oxidation of NAD + to NADH by simultaneously reducing of O 2 to H 2 O or H 2 O 2 (21). Additionally, DnaK, enolase, Elongation factor-Tu (EF-Tu), MSPB and NADH oxidase are identified to be located on the membrane of mycoplasmas (20,21,23,35,36). ...
Mycoplasma synoviae (MS) is a primary avian pathogen prevalent worldwide that causes airsacculitis and synovitis in birds. Vaccination is recommended as the most cost-effective strategy in the control of MS infection. Novel alternative vaccines are needed for eradicating and controlling MS infection in flocks. DnaK, enolase, elongation factor Tu (EF-Tu), MSPB, NADH oxidase and LP78 are the major immunogenic antigens of MS and are promising targets for subunit vaccine candidates. In the present study, genes encoding DnaK, enolase, EF-Tu, MSPB, LP78, and NADH oxidase were cloned and expressed in Escherichia coli. Enzyme-linked immunosorbent assay showed that the six recombinant proteins were recognized by convalescent sera, indicating that they were expressed during infection. Two injections of the six subunit vaccines induced a robust antibody response and increased the concentrations of IFN-γ and IL-4, especially rEnolase and rEF-Tu. The proliferation of peripheral blood lymphocytes was enhanced in all of the immunized groups. Chickens immunized with rEnolase, rEF-Tu, rLP78, and rMSPB conferred significant protection against MS infection, as indicated by significantly lower DNA copies in the trachea, lower scores of air sac lesions, and lesser tracheal mucosal thickness than that in the challenge control. Especially, rEnolase provided the best protective efficacy, followed by rEF-Tu, rMSPB, and rLP78. Our finds demonstrate that the subunit vaccines and bacterin can only reduce the lesions caused by MS infection, but not prevent colonization of the organism. Our findings may contribute to the development of novel vaccine agents against MS infection.
... Membrane lipoproteins are able to activate macrophages, thus playing an important role in cytokine production and, consequently, in the inflammatory response during infection [32]. The VlhA protein generates the N-terminal fragment of the MSPB lipoprotein and the C-terminal fragment of MSPA, which is directly involved in hemadherence [33]. The length of the MSPB lipoprotein differs between M. synoviae isolates, which alters their hemagglutination phenotype and may be related to changes in the antigenic determinants of MSPB and MSPA [30,31,33,34]. ...
... The VlhA protein generates the N-terminal fragment of the MSPB lipoprotein and the C-terminal fragment of MSPA, which is directly involved in hemadherence [33]. The length of the MSPB lipoprotein differs between M. synoviae isolates, which alters their hemagglutination phenotype and may be related to changes in the antigenic determinants of MSPB and MSPA [30,31,33,34]. M. synoviae processes involved in tissue invasion and degradation in the avian body involve the expression of cysteine proteases (CysP), which can cleave chicken IgG into Fab and Fc fragments, thus facilitating their survival in the host [35]. ...
... The bacterium can survive in the environment for several weeks, making it a persistent threat to poultry farms. [33][34][35][36] Controlling MS requires strict biosecurity measures, such as isolating infected birds, maintaining clean facilities, and disinfecting equipment. Vaccination is also an important tool in preventing and managing the disease. ...
Mycoplasma synoviae (MS) is a highly contagious bacteria that can cause significant harm in commercial poultry populations while not prevented. Rapid detection of its presence in a flock is crucial from the perspective of animals' health and economic income. Authors propose spectral measurements strongly backed up by the AI data processing algorithms for classifying egg origin: from healthy hens or MS-infected ones. The newest obtained classification factors are F-scores for white eggshells 99% and for brown eggshells 99%—all data used for classification were taken by the portable multispectral fibre-optics reflectometer.
... For detection of MS antibodies, the major membrane protein MSPB has been used as a coating antigen, and has been thought to be a specific and sensitive diagnostic antigen [48,49]. However, MSPB contains a proline-rich repeat region that is prone to insertion or deletion mutations, thus resulting in antigenic variation [50,51]. Therefore, screening a sensitive, specific, and highly conserved antigen is important. ...
... The collected MS cells were fixed with 4% paraformaldehyde and 0.05% glutaraldehyde at room temperature for 2 h, then washed three times with PBS. The fixed MS cells were dehydrated with various concentrations (30,50, and 70%) of ethanol, and embedded in LR White resin (Sigma, USA). Grids with ultrathin sections were blocked with 5% BSA and then incubated with rabbit anti-MSNOX, anti-rMSFBA serum, or pre-immune rabbit serum (1:1000 diluted by PBST) at 37 °C for 1.5 h. ...
Background
Mycoplasma synoviae (MS) is an important pathogen causing respiratory diseases and arthritis in chickens and turkeys, thus, resulting in serious economic losses to the poultry industry. Membrane-associated proteins are thought to play important roles in cytoadherence and pathogenesis. NADH oxidase (NOX) is an oxidoreductase involved in glycolysis, which is thought to be a multifunctional protein and potential virulence factor in some pathogens. However, little is known regarding the NOX of MS (MSNOX). We previously demonstrated that MSNOX was a metabolic enzyme distributed in not only the cytoplasm but also the MS membrane. This study was aimed at exploring NOX’s potential as a diagnostic antigen and its role in MS cytoadherence.
Results
Western blots and ELISAs indicated that recombinant MSNOX (rMSNOX) protein reacted with sera positive for various MS isolates, but not MG isolates or other avian pathogens, thus, suggesting that rMSNOX is a potential diagnostic antigen. In addition, rabbit anti-rMSNOX serum showed substantial complement-dependent mycoplasmacidal activity toward various MS isolates and MG R low . MSNOX protein was found not only in the cytoplasm but also on the membrane of MS through suspension immunofluorescence and immunogold electron microscopy assays. Indirect immunofluorescence assays indicated that rMSNOX adhered to DF-1 cells, and this adherence was inhibited by rabbit anti-rMSNOX, but not anti-MG serum. Furthermore, indirect immunofluorescence and colony counting assays confirmed that the rabbit anti-rMSNOX serum inhibited the adherence of various MS isolates but not MG R low to DF-1 cells. Moreover, plasminogen (Plg)- and fibronectin (Fn)-binding assays demonstrated that rMSNOX bound Plg and Fn in a dose-dependent manner, thereby further confirming that MSNOX may be a putative adhesin.
Conclusion
MSNOX was identified to be a surface immunogenic protein that has good immunoreactivity and specificity in Western blot and ELISA, and therefore, may be used as a potential diagnostic antigen in the future. In addition, rMSNOX adhered to DF-1 cells, an effect inhibited by rabbit anti-rMSNOX, but not anti-MG serum, and anti-rMSNOX serum inhibited the adherence of various MS isolates, but not MG R low , to DF-1 cells, thus indicating that the inhibition of adherence by anti-MSNOX serum was MS specific. Moreover, rMSNOX adhered to extracellular matrix proteins including Plg and Fn, thus suggesting that NOX may play important roles in MS cytoadherence and pathogenesis. Besides, rabbit anti-rMSNOX serum presented complement-dependent mycoplasmacidal activity toward both MS and MG, indicating the MSNOX may be further studied as a potential protective vaccine candidate.
... For detection of MS antibodies, the major membrane protein MSPB has been used as coating antigen, and was thought to be a speci c and sensitive diagnostic antigen [45,46]. However, the MSPB contains a proline-rich repeat region, which is prone to insertion or deletion mutation, and resulting in antigenic variation [47,48]. Therefore, screening a sensitive, speci c and highly conserved antigen is important. ...
Background
Mycoplasma synoviae (MS) is an important pathogen that causes respiratory diseases and arthritis in chickens and turkeys, resulting in serious economic losses to the poultry industry. Membrane-associated proteins were thought to play important roles in cytoadherence and pathogenesis. NADH oxidase (NOX) is a kind of oxidoreductase involved in glycolysis, which was thought to be a multifunctional protein and a potential virulence factor in some pathogens. However, there was still little knowledge about the NOX of MS (MSNOX). Our previous study has proved that the MSNOX was not only a cytoplasmic metabolic enzyme, but was also distributed in MS membrane. This study was mainly to explore the potential as a diagnostic antigen and an adhesion of the NOX in MS.
Results
In this study, Western blot analysis showed that recombinant MSNOX (rMSNOX) protein could react with positive sera against different MS isolates, but not MG isolates or other avian pathogens, suggesting the rMSNOX is a potential diagnostic antigen. In addition, the rabbit anti-rMSNOX serum showed a complement-dependent mycoplasmacidal rate as high as 86.5%. MS NOX protein has been identified as a cytoplasmic enzyme in our previous study, it was identified to be distributed on the surface of MS in this study using suspension immunofluorescence assays. Indirect immunofluorescence assays and colony counting assays showed that the rMSNOX and MS could adhere to DF-1 cells and the adherence could be significantly inhibited by the rabbit anti-rMSNOX serum. Moreover, plasminogen (Plg)- and fibronectin (Fn)-binding assays showed that rMSNOX was able to bind to Plg and Fn in a dose-dependent manner, further confirmed that MSNOX could be a putative adhesin.
Conclusion
The MSNOX was identified to be a surface immunogenic protein which also has good immunoreactivity and specificity, suggesting it may be used as a potential diagnostic antigen in future. The rMSNOX and MS presented adherence to DF-1 cells, which were inhibited by the rabbit anti-rMSNOX serum. Moreover, rMSNOX showed cytoadherence to extracellular matrix (ECM) proteins including Plg and Fn, suggesting that the NOX may play important roles in cytoadherence and pathogenesis of MS.
... Therefore, serological tests such as ELISA or hemagglutination inhibition (HI) cannot provide early diagnosis of infection caused by M. synoviae. The hemagglutination activity of M. synoviae is unstable (44). The vlhA encoding hemagglutinin itself is highly mutagenic and horizontally transfers between M. synoviae and other mycoplasmas, such as M. gallisepticum (45,46). ...
Mycoplasma synoviae is an important pathogen of poultry, causing significant economic losses in this industry. Analysis of the unique genes and shared genes among different M. synoviae strains and among related species is helpful for studying the molecular pathogenesis of M. synoviae and provides valuable molecular diagnostic targets to facilitate the identification of M. synoviae species. We selected a total of 46 strains, including six M. synoviae strains, from 25 major animal (including avian) Mycoplasma species/subspecies that had complete genome sequences and annotation information published in GenBank, and used them for comparative genomic analysis. After analysis, 16 common genes were found in the 46 strains. Thirteen single-copy core genes and the 16s rRNA genes were used for genetic evolutionary analysis. M. synoviae was found to have a distant evolutionary relationship not only with other arthritis-causing mycoplasmas, but also with another major avian pathogen, Mycoplasma gallisepticum, that shares the major virulence factor vlhA with M. synoviae. Subsequently, six unique coding genes were identified as shared among these M. synoviae strains that are absent in other species with published genome sequences. Two of the genes were found to be located in the genetically stable regions of the genomes of M. synoviae and were determined to be present in all M. synoviae isolated strains (n = 20) and M. synoviae-positive clinical samples (n = 48) preserved in our laboratory. These two genes were used as molecular diagnostic targets for which SYBR green quantitative PCR detection methods were designed. The two quantitative PCR methods exhibited good reproducibility and high specificity when tested on positive plasmid controls and genomic DNA extracted from different M. synoviae strains, other major avian pathogenic bacteria/mycoplasmas, and low pathogenic Mycoplasma species. The detection limit for the two genes was 10 copies or less per reaction. The clinical sensitivity and specificity of the quantitative PCR methods were both 100% based on testing chicken hock joint samples with positive or negative M. synoviae infection. This research provides a foundation for the study of species-specific differences and molecular diagnosis of M. synoviae.
... Molecular detection and characterization of the variable lipoprotein hemagglutinin A (vlhA) gene has been used successfully for M. synoviae strain differentiation without the need for prior culture or isolation [13][14][15]. The vlhA gene of M. synoviae is cleaved post-translationally into an N-terminal lipoprotein (MSPB), which exhibits a high degree of antigenic variation [16]. M. synoviae strain typing based on nucleotide deletion or insertion within the proline-rich repeat (PRR) region of the vlhA gene is related to the invasiveness of M. synoviae associated with infectious synovitis [13]. ...
... In M. synoviae, Haemagglutinins account among the most significant surface proteins involved in colonization and virulence of avian Mycoplasmas (Narat et al., 1998;Benčina et al., 2001). haemagglutinins are determined by sequences of a multigene family stated as variable lipoprotein hemagglutinin (vlhA) genes (Noormohammadi et al., 1997;Benčina et al., 1999). The expressed vlhA genetic factor of M. synoviae yields a product that is cleaved post-translationally into an N-terminal lipoprotein (MSPB) and a C-terminal haemagglutinin protein (MSPA) (Noormohammadi et al., 1998). ...
... Cleavage occurred directly after amino acid residue 344 (Noormohammadi et al., 2000). Both MSPA and MSPB are surface exposed proteins and show high frequency antigenic variation (Noormohammadi et al., 1997;Noormohammadi et al., 1998). Such a gene replacement mechanism, also known as gene conversion, permits a single strain of M. synoviae to create a huge number of variants by recruiting new sequences from a great pseudogene reservoir. ...
The present work was designed to make sequencing of M. synoviae isolates for identification of nucleotide differences in the M. synoviae vlhA gene which isolated from the respiratory system and Joint from chickens. A total of 224 chicken samples (109 respiratory samples, 115 joint samples) collected from birds from different flocks showing respiratory manifestation and arthritis were examined. Identification of M. synoviae by PCR Using primers corresponding to the single copy preserved 5 ́ end for vlhA genetic factor, amplicons for 350~400 bp then, generated which 6 and 26 out of 224 samples were positive samples for M. synoviae from culture and tissue by PCR respectively. High-resolution melting curve analysis (HRM) for amplicons using SYBR green fluorescent dye of 9 selected isolates (5 respiratory isolates and 4 arthirtic isolates) showed that different Melting temperature curves were ranged between 84.6-85.1°C for isolates MS from the respiratory samples and other melting temperature curves ranged between 73.6-74.6°Cfor isolates Ms from the arthirtic samples. The results proved that, there was a broad concordance among nucleotide sequence of all isolates which isolated from the respiratory system except in one sample which observed the point mutations and the frame-shift mutation in some nucleotide differ than other respiratory isolates in addition there is complete concordance between nucleotide sequence of all isolates which isolated from joint. However, in comparison the Respiratory M. synoviae isolates with M. synoviae joint isolates, there was clear variation in nucleotide sequence which was confirm the result of HRM. Compared to vaccine MS-H strain arrangement, all isolates show clear variation from (MsH) vaccine strain. This study proved a difference between M. synoviae isolated from the respiratory system and Joint and live commercial vaccine (MsH) strain. Also, these informations showed that variations in the vlhA gene sequence could be introduced into
(PDF) Molecular Characterization of Mycoplasma Synoviae Isolated From the Respiratory System and Joints of Chickens with Special Reference of vlhA Gene. Available from: https://www.researchgate.net/publication/330343501_Molecular_Characterization_of_Mycoplasma_Synoviae_Isolated_From_the_Respiratory_System_and_Joints_of_Chickens_with_Special_Reference_of_vlhA_Gene [accessed Oct 07 2020].
... Indeed, in many pathogenic species, the dynamic use of variable surface antigens can help evade the immune system and establish chronic infections in diverse human and animal hosts. In many mollicutes, genetic switches altering the expression, size, or structure of surface-exposed proteins are major means used to modify the surface topography [2][3][4][5][6][7][8]. In Mycoplasma hyopneumoniae, a mollicute responsible for the porcine enzootic pneumonia, the targeted proteolysis of surface antigens coupled with variable cleavage efficiency has been identified as another mechanism participating in the diversification of surface-exposed antigens [9][10][11][12]. ...
Mollicutes, including mycoplasmas and spiroplasmas have been considered as good representatives of the « minimal cell » concept: these wall-less bacteria are small in size, possess a minimal genome, and restricted metabolic capacities. However the recent discovery of the presence of post-translational modifications unknown so far, such as the targeted processing of membrane proteins of mycoplasma pathogens for human and swine, revealed a part of the hidden complexity of these microorganisms. In this study, we show that in the phytopathogen, insect-vectored, Spiroplasma citri ScARPs adhesins are post-translationally processed through an ATP-dependent targeted cleavage. The cleavage efficiency could be enhanced in vitro when decreasing the extracellular pH or upon addition of polyclonal antibodies directed against ScARPs repeated units, suggesting that modification of the surface charge and/or ScARPs conformational changes could initiate the cleavage. The two major sites for primary cleavage are localized within predicted disordered regions and do not fit any previously reported cleavage motif; in addition, the inhibition profile and the metal ions requirements indicate that this post-translational modification involves at least one non conventional protease. Such a proteolytic process may play a role in S. citri colonization of cells of the host insect. Furthermore our work indicates that post-translational cleavage of adhesins represents a common feature to mollicutes colonizing distinct hosts and that processing of surface antigens could represent a way to make the most out of a minimal genome.
