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![| Agmatine is critical for capsule biosynthesis in pneumococcus. Total CPS isolated from ΔspeA and ΔpotABCD cultured in THY or THY supplemented with agmatine [20 mM of agmatine, a quarter of minimum inhibitory concentration (MIC)] was spotted on a nitrocellulose membrane. Probing with anti-serotype 4 specific antibody and a horseradish peroxidase (HRP)-conjugated secondary antibody, the membrane was developed with enhanced chemiluminescence (ECL) detection and scanned using a ChemiDoc XRS+ with Image Lab software (Bio-Rad, Hercules, CA, United States). Agmatine successfully restored capsule in the two unencapsulated ΔspeA and ΔpotABCD strains in three independent experiments.](profile/Moses-Ayoola/publication/345037646/figure/fig1/AS:1182487908749312@1658938495835/Agmatine-is-critical-for-capsule-biosynthesis-in-pneumococcus-Total-CPS-isolated-from.png)
| Agmatine is critical for capsule biosynthesis in pneumococcus. Total CPS isolated from ΔspeA and ΔpotABCD cultured in THY or THY supplemented with agmatine [20 mM of agmatine, a quarter of minimum inhibitory concentration (MIC)] was spotted on a nitrocellulose membrane. Probing with anti-serotype 4 specific antibody and a horseradish peroxidase (HRP)-conjugated secondary antibody, the membrane was developed with enhanced chemiluminescence (ECL) detection and scanned using a ChemiDoc XRS+ with Image Lab software (Bio-Rad, Hercules, CA, United States). Agmatine successfully restored capsule in the two unencapsulated ΔspeA and ΔpotABCD strains in three independent experiments.
Context in source publication
Context 1
... we carried out supplementation assays with 20 mM agmatine. Our results show that one quarter MIC agmatine restores the encapsulated phenotype in ΔpotABCD and ΔspeA ( Figure 5). Supplementation of an equivalent MIC (one quarter MIC) of putrescine (0.57 mM) and spermidine (0.43 mM) failed to restore capsule in the ΔspeA strain that has an intact potABCD for the import of these polyamines (data not shown). ...
Citations
... Although, deletion of potD alone had no impact on growth in WU2 strain. However, deletion of arginine decarboxylase (ADC/speA) that synthesizes agmatine, an intermediate from the putrescine/spermidine biosynthesis pathway in serotype 4 pneumococci results in the inhibition of capsular polysaccharide (CPS) synthesis 17,18 . Exogenous supplementation of agmatine restores capsule, indicating that reduced intracellular levels of this polyamine due to impaired synthesis are critical for CPS regulation 18 . ...
... However, deletion of arginine decarboxylase (ADC/speA) that synthesizes agmatine, an intermediate from the putrescine/spermidine biosynthesis pathway in serotype 4 pneumococci results in the inhibition of capsular polysaccharide (CPS) synthesis 17,18 . Exogenous supplementation of agmatine restores capsule, indicating that reduced intracellular levels of this polyamine due to impaired synthesis are critical for CPS regulation 18 . The capsule is the principal virulence factor in pneumococcus, the most common bacterial etiology of otitis media, sepsis, and community-acquired pneumonia globally 19 . ...
... that has some minimal ODC and lysine decarboxylase (LDC) activities 18 . We determined the impact of DFMO (ODC/ADC inhibitor) and α-difluoromethylarginine (DFMA, an ADC inhibitor) on the decarboxylase activities of SP_0916. ...
Polyamines are small cationic molecules that have been linked to various cellular processes including replication, translation, stress response and recently, capsule regulation in Streptococcus pneumoniae (Spn, pneumococcus). Pneumococcal-associated diseases such as pneumonia, meningitis, and sepsis are some of the leading causes of death worldwide and capsule remains the principal virulence factor of this versatile pathogen. α-Difluoromethyl-ornithine (DFMO) is an irreversible inhibitor of the polyamine biosynthesis pathway catalyzed by ornithine decarboxylase and has a long history in modulating cell growth, polyamine levels, and disease outcomes in eukaryotic systems. Recent evidence shows that DFMO can also target arginine decarboxylation. Interestingly, DFMO-treated cells often escape polyamine depletion via increased polyamine uptake from extracellular sources. Here, we examined the potential capsule-crippling ability of DFMO and the possible synergistic effects of the polyamine transport inhibitor, AMXT 1501, on pneumococci. We characterized the changes in pneumococcal metabolites in response to DFMO and AMXT 1501, and also measured the impact of DFMO on amino acid decarboxylase activities. Our findings show that DFMO inhibited pneumococcal polyamine and capsule biosynthesis as well as decarboxylase activities, albeit, at a high concentration. AMXT 1501 at physiologically relevant concentration could inhibit both polyamine and capsule biosynthesis, however, in a serotype-dependent manner. In summary, this study demonstrates the utility of targeting polyamine biosynthesis and transport for pneumococcal capsule inhibition. Since targeting capsule biosynthesis is a promising way for the eradication of the diverse and pathogenic pneumococcal strains, future work will identify small molecules similar to DFMO/AMXT 1501, which act in a serotype-independent manner.
... Comparison of the kinetics of the enzymatic conversion of arginine, lysine and ornithine substrates by recombinant SP0916 confirms that arginine is the preferred substrate for this decarboxylase. Thus SP0916 gene in serotype 4 is indeed an arginine decarboxylase (speA) [64]. Thus, pneumococcal genomes lack annotated cadaverine biosynthesis gene cadA. ...
... Intracellular concentrations of all three polyamines were reduced when either synthesis or transport genes were deleted in type 4 strain [61]. Deletion of the polyamine transport operon (potABCD), predicted to transport putrescine and spermidine resulted in significant reduction of these two substrates in serotype 4 strain [64]. There was a significant reduction in the levels of agmatine, and N-acetylpsermidine in ΔpotABCD [64]. ...
... Deletion of the polyamine transport operon (potABCD), predicted to transport putrescine and spermidine resulted in significant reduction of these two substrates in serotype 4 strain [64]. There was a significant reduction in the levels of agmatine, and N-acetylpsermidine in ΔpotABCD [64]. Deletion of genes from spermidine synthesis pathway resulted in reduced spermidine levels in serotype 2 strain cultured in CDM [63], although there was no significant reduction when cultured in THY [64]. ...
Polyamines are common intracellular metabolites of nearly all cells, and their conservation across a vast diversity of cells suggests critical roles for these compounds in cellular physiology. Most intracellular polyamines are associated with RNA and, subsequently, polyamines have significant effects on transcription and translation. Putrescine and spermidine are the most common polyamines in bacteria. Intracellular polyamine pools in bacteria are tightly controlled by both de novo synthesis and transport. Polyamine homeostasis is emerging as a critical parameter of multiple pathways and physiology with substantial impact on bacterial pathogenesis, including the important human pathogen Streptococcus pneumoniae. Modulation of polyamine metabolism in pneumococci is an important regulator of central metabolism. It has broad effects on virulence factors such as capsule as well as stress responses that ultimately impact the survival of pneumococcus in a host. Polyamine transport protein as a single antigen or in combination with other pneumococcal proteins is shown to be an efficacious immunogen that protects against nasopharyngeal colonization, and invasive disease. A comprehensive description of polyamine metabolic pathways and their intersection with pneumococcal pathogenesis will undoubtedly point to novel approaches for treatment and prevention of pneumococcal disease.
... Therefore, reduced polyamine synthesis that results in altered levels of intracellular polyamines is expected to render ΔspeA more susceptible to stress [4,8,9,[19][20][21][22][23][24][25][26][27]. Indeed, when we characterized the proteome and transcriptome of ΔspeA, we observed a shift in the carbon flow toward the pentose phosphate pathway [13,14], a signature of oxidative stress [16]. In this study, measurement of parameters indicative of cellular stress and rigorous analysis of the susceptibility of WT and ΔspeA strains to various stressors validated the previously reported signature of oxidative stress at the molecular level. ...
... Therefore, reduced polyamine synthesis that results in altered levels of intracellular polyamines is expected to render ∆speA more susceptible to stress [4,8,9,[19][20][21][22][23][24][25][26][27]. Indeed, when we characterized the proteome and transcriptome of ∆speA, we observed a shift in the carbon flow toward the pentose phosphate pathway [13,14], a signature of oxidative stress [16]. In this study, measurement of parameters indicative of cellular stress and rigorous analysis of the susceptibility of WT and ∆speA strains to various stressors validated the previously reported signature of oxidative stress at the molecular level. ...
... A prolonged lag phase in the mutant at all pH values suggests that speA's indirect effects could be essential for replication. These results concur with our earlier study where we reported reduced expression of genes involved in protein and capsule synthesis in ∆speA [13,14]. These results are consistent with studies on other pathogenic bacteria that report the neutralizing effects of polyamines (cadaverine) at low pH [26,36,53,54]. ...
Polyamines such as putrescine, cadaverine, and spermidine are small cationic molecules that play significant roles in cellular processes, including bacterial stress responses and host–pathogen interactions. Streptococcus pneumoniae is an opportunistic human pathogen, which causes several diseases that account for significant morbidity and mortality worldwide. As it transits through different host niches, S. pneumoniae is exposed to and must adapt to different types of stress in the host microenvironment. We earlier reported that S. pneumoniae TIGR4, which harbors an isogenic deletion of an arginine decarboxylase (ΔspeA), an enzyme that catalyzes the synthesis of agmatine in the polyamine synthesis pathway, has a reduced capsule. Here, we report the impact of arginine decarboxylase deletion on pneumococcal stress responses. Our results show that ΔspeA is more susceptible to oxidative, nitrosative, and acid stress compared to the wild-type strain. Gene expression analysis by qRT-PCR indicates that thiol peroxidase, a scavenger of reactive oxygen species and aguA from the arginine deiminase system, could be important for peroxide stress responses in a polyamine-dependent manner. Our results also show that speA is essential for endogenous hydrogen peroxide and glutathione production in S. pneumoniae. Taken together, our findings demonstrate the critical role of arginine decarboxylase in pneumococcal stress responses that could impact adaptation and survival in the host.
... hepatic, and neurological dysfunction (5,6), and is associated with high morbidity and mortality (7). However, to date, there is still no specific medicine nor effective therapy for the treatment of patients with sepsis syndrome. ...
Background:
Sepsis is an excessive inflammatory response to an infection that fails to return to homeostasis. It occurs frequently in patients following a primary infection or injury and is one of the most common causes of mortality in hospitalized patients. However, there is currently no specific and effective therapy for the management of sepsis. Previous findings have suggested that cinnamon and cinnamon extracts have anti-inflammatory and anti-oxidative activities and therefore, may be effective in treating sepsis.
Methods:
In the present study, Escherichia coli was injected into mice to induce sepsis. Hematoxylin and eosin staining was used to investigate the influence of cinnamyl alcohol on histological changes including heart, liver, lung, and kidney tissues. Western blotting and real-time polymerase chain reaction (RT-PCR) were applied to measure the levels of NLRP3 inflammasome. The levels of interleukin (IL)-1β and IL-18 in the serum were detected with enzyme-linked immunosorbent assay (ELISA) method.
Results:
Administration of cinnamyl alcohol by gavage effectively reduced the mortality of septic mice (70% survival), compared to untreated septic mice (50% survival). The histological findings indicated that cinnamyl alcohol reduced the inflammatory reaction in the liver, heart, lungs, and kidneys of the septic mice. In the circulatory system, the concentrations of the inflammatory cytokines IL-1β and IL-18 were significantly decreased by cinnamyl alcohol administration compared to the untreated septic group. Western blot analysis and quantitative polymerase chain reaction (qPCR) demonstrated that cinnamyl alcohol decreased the expression of apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC), nucleotide-binding oligomerization domain-like receptor 3 (NLRP3), and caspase-1 in the liver, heart, lungs, and kidneys of the mice, suggesting that cinnamyl alcohol alleviated sepsis syndrome via the NLRP3 inflammasome pathway.
Conclusions:
Cinnamyl alcohol may be a novel therapeutic candidate for the treatment of sepsis syndrome.
