Mary Beth Mudgett

Stanford University | SU · Department of Biology

N-hydroxy-pipecolic acid (NHP) is a mobile metabolite essential for inducing and amplifying systemic acquired resistance (SAR) following pathogen attack. Early phases of NHP signaling leading to immunity have remained elusive. Here we report the early transcriptional changes mediated by NHP and the role salicylic acid (SA) plays during this respons...

In both plants and animals, nucleotide-binding leucine-rich repeat (NLR) immune receptors play critical roles in pathogen recognition and activation of innate immunity. In plants, NLRs recognise pathogen-derived effector proteins and initiate effector-triggered immunity (ETI). However, the molecular mechanisms that link NLR-mediated effector recogn...

Hundreds of leucine-rich repeat receptor kinases (LRR-RKs) have evolved to control diverse processes of growth, development and immunity in plants, but the mechanisms that link LRR-RKs to distinct cellular responses are not understood. Here we show that two LRR-RKs, the brassinosteroid hormone receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1) and the f...

Beyond its role in cellular homeostasis, autophagy plays anti-and promicrobial roles in host-microbe interactions, both in animals and plants. One prominent role of antimicrobial autophagy is to degrade intracellular pathogens or microbial molecules, in a process termed xenophagy. Consequently, microbes evolved mechanisms to hijack or modulate auto...

Beyond its role in cellular homeostasis, autophagy plays anti- and pro-microbial roles in host-microbe interactions, both in animals and plants. One prominent role of anti-microbial autophagy is to degrade intracellular pathogens or microbial molecules, in a process termed xenophagy. Consequently, microbes evolved mechanisms to hijack or modulate a...

Systemic acquired resistance (SAR) is a mechanism that plants utilize to connect a local pathogen infection to global defense responses. N-hydroxy-pipecolic acid (NHP) and a glycosylated derivative are produced during SAR, yet their individual roles in this process are currently unclear. Here, we report that Arabidopsis thaliana UGT76B1 generated g...

The induction of plant nutrient secretion systems is critical for successful pathogen infection. Some bacterial pathogens (e.g., Xanthomonas spp.) use transcription activator-like (TAL) effectors to induce transcription of SWEET sucrose efflux transporters. Pseudomonas syringae pv. tomato strain DC3000 lacks TAL effectors yet is able to induce mult...

A bstract The induction of plant nutrient secretion systems is critical for successful pathogen infection. Some bacterial pathogens, e.g. Xanthomonas species, use TAL (transcription activator-like) effectors to induce transcription of SWEET sucrose efflux transporters. Pseudomonas syringae pathovar (pv.) tomato strain DC3000 lacks TAL effectors, ye...

Systemic acquired resistance (SAR) is a mechanism that plants utilize to connect a local pathogen infection to global defense responses. N -hydroxy-pipecolic acid (NHP) and a glycosylated derivative are produced during SAR, yet their individual roles in the response have not yet been elucidated. Here we report that Arabidopsis thaliana UGT76B1 can...

Tomato Atypical Receptor Kinase 1 (TARK1) is a pseudokinase required for post-invasion immunity. TARK1 was originally identified as a target of the Xanthomonas euvesicatoria effector protein Xanthomonas outer protein N (XopN), a suppressor of early defense signaling. How TARK1 participates in immune signal transduction is not well understood. To ga...

In response to biotic stress, plants produce suites of highly modified fatty acids that bear unusual chemical functionalities. Despite their chemical complexity and proposed roles in pathogen defense, little is known about the biosynthesis of decorated fatty acids in plants. Falcarindiol is a prototypical acetylenic lipid present in carrot, tomato,...

Systemic acquired resistance (SAR) is a powerful immune response that triggers broad-spectrum disease resistance throughout a plant. In the model plant Arabidopsis thaliana , long-distance signaling and SAR activation in uninfected tissues occur without circulating immune cells and instead rely on the metabolite N- hydroxy-pipecolic acid (NHP). Eng...

Effector-dependent manipulation of host transcription is a key virulence mechanism used by Xanthomonas species causing bacterial spot disease in tomato and pepper. Transcription activator-like (TAL) effectors employ novel DNA-binding domains to directly activate host transcription, whereas the non-TAL effector XopD uses a small ubiquitin-like modif...

Among the hundreds of receptor-like kinases (RLKs) in plants, the brassinosteroid (BR) hormone receptor BR-INSENSITIVE 1 (BRI1) and the immunity receptor FLAGELLIN SENSING 2 (FLS2) share a common co-receptor kinase, but lead to distinct growth and immunity responses, respectively. Here we show that the BSU1 family of phosphatases, known to mediate...

Signal propagation and the coordination of whole-organism responses in plants rely heavily on small molecules. Systemic acquired resistance (SAR) is one such process in which long-distance signaling activates immune responses in uninfected tissue as a way to limit the spread of a primary, localized infection. Recently, N -hydroxy pipecolic acid (NH...

We demonstrated previously that expression of Macrosiphum euphorbiae salivary protein Me10 enhanced aphid reproduction on its host tomato ( Solanum lycopersicum ). However, the mechanism of action of Me10 remained elusive. To confirm the secretion of Me10 by the aphid into plant tissues, we produced Me10 polyclonal antibodies. To identify the plant...

In response to biotic stress, plants reshape their complement of lipids to produce suites of highly modified fatty acids that bear unusual chemical functionality. Despite their chemical complexity, proposed roles in pathogen defense and presence in crop plants, little is known about the biosynthesis of these decorated fatty acids. Falcarindiol is a...

14-3-3s are phospho-binding proteins with scaffolding activity that play central roles in the regulation of enzymes and signaling complexes in eukaryotes. In plants, 14-3-3 isoforms are required for disease resistance and key targets of pathogen effectors. Here, we examined the requirement of the tomato (Solanum lycopersicum) 14-3-3 (TFT) protein f...

Significance Plants lack circulating immune cells and instead rely on small molecule chemistry for local and long-distance defense signaling. Following pathogen attack, plants activate innate immune pathways at the site of infection to limit pathogen growth. Plants also possess the ability to prime similar immune responses in uninfected tissues to...

Systemic acquired resistance (SAR) is a global response in plants induced at the site of infection that leads to long-lasting and broad-spectrum disease resistance at distal, uninfected tissues. Despite the importance of this priming mechanism, the identity of the mobile defense signal that moves systemically throughout plants to initiate SAR has r...

Ethylene is a gaseous plant hormone controlling fruit ripening, flower opening, leaf senescence as well as abscission, and disease symptom development. Ethylene plays a critical role in the bacterial pathogen Xanthomonas euvesicatoria (X. euvesicatoria)-elicited symptom development in tomato. This protocol describes the measurement of ethylene gas...

The IC-MPMI was held in Rhodes, Greece from July 6-10, 2014. A new feature of the meeting was the inclusion of a “Student Travel Workshop”. In honor of our late colleague Ko Shimamoto, a student travel fellowship program was initiated to enrich graduate student and postdoctoral participation at this congress. The fellowship program was generously s...

Many phytopathogenic type III secretion effectors (T3Es) have been shown to target and suppress plant immune signaling, but perturbation of the plant immune system by T3Es can also elicit a plant response. XopX is a "core" Xanthomonas T3E that contributes to growth and symptom development during Xanthomonas euvesicatoria (Xe) infection of tomato, b...

The IC-MPMI was held in Rhodes, Greece from July 6-10, 2014. A new feature of the meeting was the inclusion of a "Student Travel Workshop". In honor of our late colleague Ko Shimamoto, a student travel fellowship program was initiated to enrich graduate student and postdoctoral participation at this congress. The fellowship program was generously s...

Truncated transcription factor-like proteins called microProteins can modulate transcription factor activities, thereby increasing transcriptional regulatory complexity. To understand their prevalence, evolution, and function, we predicted over 400 genes that encode putative microProteins from Arabidopsis thaliana using a bioinformatics pipeline, a...

The trade-off between growth and immunity is crucial for survival in plants. However, the mechanism underlying growth-immunity balance has remained elusive. The PRE-IBH1-HBI1 tripartite helix-loop-helix/basic helix-loop-helix module is part of a central transcription network that mediates growth regulation by several hormonal and environmental sign...

Bacterial pathogens of plant and animals share a homologous group of virulence factors, referred to as the YopJ effector family, which are translocated by the type III secretion (T3S) system into host cells during infection. Recent work indicates that some of these effectors encode acetyltransferases that suppress host immunity. The YopJ-like prote...

The third edition of the Handbook of Proteolytic Enzymes aims to be a comprehensive reference work for the enzymes that cleave proteins and peptides, and contains over 800 chapters. Each chapter is organized into sections describing the name and history, activity and specificity, structural chemistry, preparation, biological aspects, and distinguis...

Effector-triggered immunity (ETI) to host-adapted pathogens is associated with elicitation of cell death at the infection site. The plant-pathogenic bacterium Xanthomonas euvesicatoria (Xcv) interferes with plant cellular processes by injecting effector proteins into host cells through the type III secretion system. Here, we show that the Xcv effec...

Protein kinase-like domains that lack conserved residues known to catalyze phosphoryl transfer, termed pseudokinases, have emerged as important signaling domains across the kingdoms of life. Although predicted to function principally as catalysis-independent protein interaction modules, several pseudokinase domains have been attributed unexpected c...

XopD, a type III secretion effector from Xanthomonas euvesicatoria (Xcv), the causal agent of bacterial spot of tomato, is required for pathogen growth and delay of host symptom development. XopD carries a C-terminal SUMO protease domain, a host range determining nonspecific DNA-binding domain and two EAR motifs typically found in repressors of str...

Xanthomonas campestris pv. vesicatoria (Xcv) possess a type 3 secretion system (T3SS) to deliver effector proteins into its Solanaceous host plants. These proteins are involved in suppression of plant defense and in reprogramming of plant metabolism to favour bacterial propagation. There is increasing evidence that hexoses contribute to defense res...

Primers used for generation of different Xcv strains. Added restriction sites were marked by bold letters. (DOCX)

Cw-Inv activity in pepper leaves after infiltration with Xcv wild type and Xcv mutant strains at a concentration of 109 cfu ml−1. Values represent the mean ± SD from two different experiments each with four independent samples. Black bars: before infection. Light grey: 2 days post infection (dpi). Dark grey: 3 dpi. (TIF)

Xcv ΔxopB (Δ1257) induces a strong induction of cw-Inv activity which is complemented by plasmid-borne expression of XopB. Susceptible pepper leaves were inoculated with Xcv wild type (wt), Xcv ΔxopB (Δ1257) containing both the pBBR1MCS5 vector (EV), or a Xcv ΔxopB (Δ1257) derivative in which a genomic fragment was introduced containing the putativ...

Constitutive expression of xopB in transgenic tobacco and tomato plants. The xopB open reading frame was inserted into the binary vector pBinAR between the CaMV 35S promoter and the polyadenylation site of the octopin synthase from Agrobacterium tumefaciens and transformed into tobacco and tomato plants. A.) Analysis of xopB-specific mRNA accumulat...

Relative TFT1, TFT3 and TFT6 mRNA levels in the control (TRV2) and TFT1 silenced (TRV2-TFT1) tomato lines used in Figure 2. Total RNA isolated from leaves prior to growth curve analysis was used for Q-PCR to monitor (A) TFT1, (B) TFT3, and (C) TFT6 mRNA levels in TRV2 or TRV2-TFT1 tomato lines inoculated with Xcv, Xcv ΔxopN, or Xcv ΔhrpF at day 0....

XopN(1–349)-6xHis associates with TARK1-HA. Pull-down analysis of TARK1-HA and XopN-6His, XopN(1–349)-6His, or XopN(345–733)-6His transiently over-expressed in N. benthamiana leaves using Agrobacteria. Leaves were hand-infiltrated with a 6×108 CFU/mL suspension of A. tumefaciens co-expressing TARK1-HA, and XopN-6His, XopN(1–349)-6His, or XopN(345–7...

Protein gel blot analysis and confocal microscopy for BiFC analyses. (A) Protein gel blot analysis of the BiFC assay monitoring XopN/TFT1 interactions shown in Figure 8B. Anti-XopN, anti-His and anti-GFP sera were used. (B) BiFC assay of XopN/TARK1 interactions in N. benthamiana leaves. Leaves were hand-infiltrated with a 8×108 CFU/mL total suspens...

Relative TFT1 mRNA levels in the control (TRV2) and TFT1-silenced (TRV2-TFT1) tomato lines used in Figure 3. Total RNA isolated from infected leaves at 6 HPI was used for Q-PCR. Actin mRNA expression was used to normalize the expression value in each sample. Error bars indicate SD for four plants. (TIF)

Protein gel blot analysis of proteins isolated from the yeast strains described in Figure 4B. Total protein was extracted from yeast cells and then examined by protein gel blot analysis using GAL4-DBD or HA antisera. Yeast strains analyzed were AH109 carrying pXDGATcy86 (vector, xopN, xopN(N), xopN(C), xopN(M4), xopN(M5), or xopN(M6)) and pGADT7(ve...

The putative 14-3-3 binding sites and PEST motif are not required for TFT1 binding in planta. (A) XopN-ΔM1/M2-6His and (B) XopN-ΔPEST-6His interact with TFT1 in N. benthamiana. Leaves were hand-infiltrated with a 6×108 CFU/mL suspension of A. tumefaciens co-expressing TFT1-HA and XopN-6His, XopN-ΔM1/M2-6His, and XopN-ΔPEST-6His. After 48 h, protein...

Protein gel blot analysis for TARK1/TFT1 BiFC assays shown in Figure 9A-E. Proteins were isolated from infected N. benthamiana leaves at 48 HPI and then analyzed by gel blot analysis using anti-His, anti-HA, and anti-c-Myc sera. Lane 1: XopN-6His+TARK1-SCFP3Ac+TFT1-VenusN; Lane 2: XopN-(L64A,L65A)-6His+TARK1-SCFP3Ac+TFT1-VenusN; Lane 3: XopN-(S688A...

Protein gel blot analysis of wild-type XopN-HA or XopN mutants in Xcv ΔxopN cell extracts. (A) Protein expression levels of XopN-HA or XopN(1–604)-HA in Xcv ΔxopN cell extracts for data shown in Figure 5. (B) Protein expression levels of XopN-HA, XopN(S688A)-HA, XopN(S688D)-HA, or XopN(S688E)-HA in Xcv ΔxopN cell extracts for data shown in Figure 6...

TARK1 and TFT1 interaction with XopN(L64A,L65A,S688A) triple mutant in yeast. (A) Yeast strain AH109, pXDGATcy86(GAL4-DNA binding domain) containing XopN, XopN(L64A,L65A), XopN(S688A), or XopN(L64A,L65A,S688A) were independently transformed with the following PREY constructs: pGADT7(GAL4 activation domain) alone (Vector) or pGADT7 containing TARK1C...

XopN(S688A)-6His interacts with TARK1-HA in pull-down assay. Pull-down analysis of TARK1-HA and XopN-6His, XopN(L64A,L65A)-6His, or XopN(S688A)-6His transiently over-expressed in N. benthamiana leaves using Agrobacteria. Leaves were hand-infiltrated with a 6×108 CFU/mL suspension of A. tumefaciens expressing TARK1-HA or co-expressing TARK1-HA and X...

List of primers used in this study. (DOC)

XopN is a type III effector protein from Xanthomonas campestris pathovar vesicatoria that suppresses PAMP-triggered immunity (PTI) in tomato. Previous work reported that XopN interacts with the tomato 14-3-3 isoform TFT1; however, TFT1's role in PTI and/or XopN virulence was not determined. Here we show that TFT1 functions in PTI and is a XopN viru...

In September 2008, a new blight disease appeared on basmati rice (Oryza sativa L.) in fields in the northern states of India, including Uttar Pradesh, Haryana, and Punjab. First symptoms were water-soaked lesions at the tip of rice leaves. Lesions eventually spread down the leaf blades. Infected leaves turned light brown, exhibiting a blighted appe...

XopD is a type III effector protein that is required for Xanthomonas campestris pathovar vesicatoria (Xcv) growth in tomato. It is a modular protein consisting of an N-terminal DNA-binding domain, two ethylene-responsive element binding factor-associated amphiphilic repression (EAR) transcriptional repressor motifs and a C-terminal small ubiquitin-...

Sugar efflux transporters are essential for the maintenance of animal blood glucose levels, plant nectar production, and plant seed and pollen development. Despite broad biological importance, the identity of sugar efflux transporters has remained elusive. Using optical glucose sensors, we identified a new class of sugar transporters, named SWEETs,...

XopN is a virulence factor from Xanthomonas campestris pathovar vesicatoria (Xcv) that is translocated into tomato (Solanum lycopersicum) leaf cells by the pathogen's type III secretion system. Xcv DxopN mutants are impaired in growth and have reduced ability to elicit disease symptoms in susceptible tomato leaves. We show that XopN action in plant...

Arabidopsis thaliana ecotype Pi-0 is resistant to Pseudomonas syringae pathovar tomato (Pst) strain DC3000 expressing the T3S effector protein AvrBsT. Resistance is due to a loss of function mutation (sober1-1) in a conserved alpha/beta hydrolase, SOBER1 (Suppressor of AvrBsT Elicited Resistance1). Members of this superfamily possess phospholipase...

XopN is a virulence factor from Xanthomonas campestris pathovar vesicatoria (Xcv) that is translocated into tomato (Solanum lycopersicum) leaf cells by the pathogen's type III secretion system. Xcv DxopN mutants are impaired in growth and have reduced ability to elicit disease symptoms in susceptible tomato leaves. We show that XopN action in plant...

We demonstrate that XopD, a type III effector from Xanthomonas campestris pathovar vesicatoria (Xcv), suppresses symptom production during the late stages of infection in susceptible tomato (Solanum lycopersicum) leaves. XopD-dependent delay of tissue degeneration correlates with reduced chlorophyll loss, reduced salicylic acid levels, and changes...

Histidine kinases, used for environmental sensing by bacterial two-component systems, are involved in regulation of bacterial gene expression, chemotaxis, phototaxis, and virulence. Flavin-containing domains function as light-sensory modules in plant and algal phototropins and in fungal blue-light receptors. We have discovered that the prokaryotes...

Leaves are reported to contain a secreted alpha-amylase that accumulates during senescence or after biotic or abiotic stress; however, a gene encoding this enzyme has not been described. Because a secreted amylase is isolated from plastidic starch, the function of this enzyme is difficult to predict, but circumstantial evidence suggests that it may...

AvrBsT is a type III effector from Xanthomonas campestris pv vesicatoria that is translocated into plant cells during infection. AvrBsT is predicted to encode a Cys protease that targets intracellular host proteins. To dissect AvrBsT function and recognition in Arabidopsis thaliana, 71 ecotypes were screened to identify lines that elicit an AvrBsT-...

Phytopathogenic bacteria use the type III secretion system (TTSS) to inject effector proteins into plant cells. This system is essential for bacteria to multiply in plant tissue and to promote the development of disease symptoms. Until recently, little was known about the function of TTSS effectors in bacterial-plant interactions. New studies disse...

The bacterial pathogen Xanthomonas campestris pv. vesicatoria (Xcv) uses a type III secretion system (TTSS) to translocate effector proteins into host plant cells. The TTSS is required for Xcv colonization, yet the identity of many proteins translocated through this apparatus is not known. We used a genetic screen to functionally identify Xcv TTSS...

Phytopathogenic bacteria use the type-III secretion system (TTSS) to inject effector proteins into plant cells, presumably to colonize their hosts. The function of these proteins inside plant cells has remained a mystery for years. The recent discovery that the effectors XopD, AvrXv4, AvrPphB, and AvrRpt2 have cysteine protease functions reveals th...

Homologs of the Yersinia virulence factor YopJ are found in both animal and plant bacterial pathogens, as well as in plant symbionts. The conservation of this effector family indicates that several pathogens may use YopJ-like proteins to regulate bacteria-host interactions during infection. YopJ and YopJ-like proteins share structural homology with...

Tn5 insertion mutants of Xanthomonas campestris pv. vesicatoria were inoculated into tomato and screened for reduced virulence. One mutant exhibited reduced aggressiveness and attenuated growth in planta. Southern blot analyses indicated that the mutant carried a single Tn5 insertion not associated with previously cloned pathogenicity-related genes...

Xanthomonas campestris pathovar vesicatoria (Xcv) uses the type III secretion system (TTSS) to inject effector proteins into cells of Solanaceous plants during pathogenesis. A number of Xcv TTSS effectors have been identified; however, their function in planta remains elusive. Here, we provide direct evidence for a functional role for a phytopathog...

Recent studies in bacterial pathogenesis reveal common and contrasting mechanisms of pathogen virulence and host resistance in plant and animal diseases. This review presents recent developments in the study of plant and animal pathogenesis, with respect to bacterial colonization and the delivery of effector proteins to the host. Furthermore, host...

Plants have evolved a large number of disease resistance genes that encode proteins containing conserved structural motifs that function to recognize pathogen signals and to initiate defense responses. The Arabidopsis RPS2 gene encodes a protein representative of the nucleotide-binding site-leucine-rich repeat (NBS-LRR) class of plant resistance pr...

Homologs of the Yersinia virulence effector YopJ are found in both plant and animal bacterial pathogens, as well as plant symbionts. These YopJ family members were shown to act as cysteine proteases. The catalytic triad of the protease was required for inhibition of the mitogen-activated protein kinase (MAPK) and nuclear factor kappaB (NF-kappaB) s...

Strains of Xanthomonas campestris pv. vesicatoria (Xcv) carrying avrBs2 are specifically recognized by Bs2 pepper plants, resulting in localized cell death and plant resistance. Agrobacterium-mediated transient expression of the Xcv avrBs2 gene in plant cells results in Bs2-dependent cell death, indicating that the AvrBs2 protein alone is sufficien...

Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000) expressing avrRpt2 is specifically recognized by plant cells expressing RPS2 activity, resulting in localized cell death and plant resistance. Furthermore, transient expression of this bacterial avrRpt2 gene in plant cells results in RPS2-dependent cell death. This indicates that the AvrRpt...

Pathogenic strains of Pseudomonas syringae pv. tomato carrying the avrRpt2 avirulence gene specifically induce a hypersensitive cell death response in Arabidopsis plants that contain the complementary RPS2 disease resistance gene. Transient expression of avrRpt2 in Arabidopsis plants having the RPS2 gene has been shown to induce hypersensitive cell...

Progress in the genetic and biochemical dissection of the hrp-encoded type III secretion pathway has revealed new mechanisms by which phytophathogenic bacteria infect plants. The suggestion that bacterial gene products are ‘delivered to’ and ‘perceived by’ plants cells has fundamentally changed the way in which plant—bacterial interactions are now...

Protein L-isoaspartate (D-aspartate) O-methyltransferases (MTs; EC 2.1.1.77) can initiate the conversion of detrimental L-isoaspartyl residues in spontaneously damaged proteins to normal L-aspartyl residues. We detected this enzyme in 45 species from 23 families representing most of the divisions of the plant kingdom. MT activity is often localized...

Protein L-isoaspartate (D-aspartate) O-methyltransferases (MTs; EC 2.1.1.77) can initiate the conversion of detrimental L-isoaspartyl residues in spontaneously damaged proteins to normal L-aspartyl residues. We detected this enzyme in 45 species from 23 families representing most of the divisions of the plant kingdom. MT activity is often localized...

Protein-L-isoaspartate (D-aspartate) O-methyltransferases (EC 2.1.1.77) that catalyze the transfer of methyl groups from S-adenosylmethionine to abnormal L-isoaspartyl and D-aspartyl residues in a variety of peptides and proteins are widely distributed in procaryotes and eucaryotes. These enzymes participate in the repair of spontaneous protein dam...

A 1,288 +/- 271-yr-old (1,350 +/- 220 yr BP, radiocarbon age) seed of Sacred Lotus (Nelumbo nucifera Gaertn.) from an ancient lake bed at Pulantien, Liaoning Province, China, has been germinated and subsequently radiocarbon dated. This is the oldest demonstrably viable and directly dated seed ever reported, the preserved relict of one of the early...

A 1,288 ± 271-yr-old (1,350 ± 220 yr BP, radiocarbon age) seed of Sacred Lotus (Nelumbo nucifera Gaertn.) from an ancient lake bed at Pulantien, Liaoning Province, China, has been germinated and subsequently radiocarbon dated. This is the oldest demonstrably viable and directly dated seed ever reported, the preserved relict of one of the early crop...

The L-isoaspartyl protein methyltransferase (EC 2.1.1.77) has been proposed to be involved in the repair of spontaneously damaged proteins by facilitating the conversion of abnormal L-isoaspartyl residues to normal L-aspartyl residues. Based on the abundance of this enzyme in the seeds of a variety of plants and its unique substrate specificity, it...

Protein carboxyl methyltransferases (EC 2.1.1.77) that catalyze the transfer of a methyl group from S-adenosylmethionine to L-isoaspartyl and D-aspartyl residues in a variety of peptides and proteins are widely, but not universally, distributed in nature. These enzymes can participate in the repair of damaged proteins by facilitating the conversion...