Substrate Report for: Methyl-salicylateSalicylic Acid (SA) can be methylated or conjugated to glucose. SA is a natural beta hydroxy acid in plants (bark of the white willow and wintergreen leaves).SA is a critical signal for the activation of plant defense responses against pathogen infections. SABP2 binds SA with high affinity (Kd of 90 nM). SABP2 has strong esterase activity with methyl salicylate. SA has direct activity as an anti-inflammatory agent and acts as a topical antibacterial agent due to its ability to promote exfoliation. Methyl 2-hydroxybenzoate is found in beverages. Methyl 2-hydroxybenzoate is present in white wine, tea, porcini mushroom Boletus edulis, Bourbon vanilla, clary sage, red sage and fruits including cherry, apple, raspberry, papaya and plum. Methyl 2-hydroxybenzoate is found in leaves of Gaultheria procumbens (wintergreen). Methyl 2-hydroxybenzoate is a flavouring agent. General
Target
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Martinez-Martinez M, Coscolin C, Santiago G, Chow J, Stogios PJ, Bargiela R, Gertler C, Navarro-Fernandez J, Bollinger A and Ferrer M <32 more author(s)> Martinez-Martinez M, Coscolin C, Santiago G, Chow J, Stogios PJ, Bargiela R, Gertler C, Navarro-Fernandez J, Bollinger A, Thies S, Mendez-Garcia C, Popovic A, Brown G, Chernikova TN, Garcia-Moyano A, Bjergah GE, Perez-Garcia P, Hai T, Del Pozo MV, Stokke R, Steen IH, Cui H, Xu X, Nocek BP, Alcaide M, Distaso M, Mesa V, Pelaez AI, Sanchez J, Buchholz PCF, Pleiss J, Fernandez-Guerra A, Glockner FO, Golyshina OV, Yakimov MM, Savchenko A, Jaeger KE, Yakunin AF, Streit WR, Golyshin PN, Guallar V, Ferrer M (- 32) Ref: ACS Chemical Biology, 13:225, 2018 : PubMed ESTHER: Martinez-Martinez_2018_ACS.Chem.Biol_13_225 PubMedSearch: Martinez-Martinez 2018 ACS.Chem.Biol 13 225 PubMedID: 29182315 Gene_locus related to this paper: 9zzzz-a0a2k8jn75, 9zzzz-a0a2k8jt94, 9zzzz-a0a0g3fj44, 9zzzz-a0a0g3fh10, 9zzzz-a0a0g3fh03, 9bact-a0a1s5qkj8, 9zzzz-a0a0g3feh5, 9zzzz-a0a0g3fkz4, 9zzzz-a0a0g3fh07, 9zzzz-a0a0g3fh34, 9zzzz-a0a0g3fh31, 9bact-KY458167, alcbs-q0vqa3, 9bact-a0a1s5qki8, 9zzzz-a0a0g3feq8, 9zzzz-a0a0g3feh8, 9zzzz-a0a0g3fh19, 9bact-KY203037, 9bact-a0a1s5ql22, 9bact-a0a1s5qm34, 9bact-KY203034, 9bact-r9qzg0, 9bact-a0a1s5qly8, 9zzzz-a0a0g3fkz8, 9zzzz-a0a0g3feg9, 9zzzz-KY203033, 9zzzz-a0a0g3fes4, 9zzzz-a0a0g3fh42, 9bact-a0a1s5qlx2, 9zzzz-KY483651, 9bact-a0a1s5qmh4, 9zzzz-KY203032, 9zzzz-EH87, 9zzzz-a0a0g3fei1, 9zzzz-a0a0g3fet2, 9zzzz-KY483647, 9zzzz-EH82, 9zzzz-a0a0g3fe15, 9bact-KY203031, 9bact-t1w006, 9zzzz-a0a0g3fet6, 9bact-KY458164, geoth-g8myf3, 9bact-a0a1s5ql04, 9gamm-a0a1y0ihk7, 9bact-a0a1s5qly6, 9bact-a0a1s5qkg4, 9bact-a0a1s5qkm4, 9gamm-s5tv80, 9gamm-a0a0c4zhg2, 9zzzz-t1b379, 9gamm-KY483646, 9bact-KY458160, 9zzzz-a0a0g3fj57, 9gamm-s5t8349, 9arch-KY203036, 9bact-KY458168, 9zzzz-a0a0g3fes0, 9zzzz-t1be47, 9bact-KY458159, 9zzzz-a0a0g3fh39, 9bact-t1vzd5, 9prot-EH41, 9bact-Lip114, alcbs-q0vt77, 9bact-a0a1s5qke6, 9bact-a0a1s5qkf3, 9prot-SRP030024, 9gamm-s5t532, 9bact-a0a1s5qkl2, 9bact-a0a1s5qkk8, 9zzzz-KY203030, 9zzzz-t1d4I7, 9prot-KY019260, 9bact-a0a1s5qm38, 9arch-KY458161, 9prot-KY010302, 9zzzz-a0a0g3fl25, 9actn-KY010298, 9gamm-s5u059, 9bact-a0a1s5qmi7, 9bact-KY010297, 9bact-KY483642, 9bact-a0a1s5qkj1, 9bact-KY010299, 9bact-KY483648, alcbs-q0vtl7, 9bact-a0a1s5qf1, 9bact-a0a1s5qkg0, 9bact-a0a0h4tgu6, 9bact-MilE3, 9bact-LAE6, 9alte-MGS-MT1, 9bact-r9qzf7, 9gamm-k0c6t6, alcbs-q0vl36, alcbs-q0vlq1, alcbs-q0vq49, bacsu-pnbae, canar-LipB, canan-lipasA, geost-lipas, marav-a1u5n0, pseps-i7k8x5, staep-GEHD, symth-q67mr3, altma-s5cfn7, cycsp-k0c2b8, alcbs-q0vlk5, 9bact-k7qe48, 9bact-MGS-M1, 9bact-MGS-M2, 9bact-a0a0b5kns5, 9zzzz-a0a0g3fej4, 9zzzz-a0a0g3fj60, 9zzzz-a0a0g3fej0, 9zzzz-a0a0g3fj64, 9bact-a0a0b5kc16, 9zzzz-a0a0g3feg6, 9zzzz-a0a0g3feu6 Abstract Esterases receive special attention because their wide distribution in biological systems and environments and their importance for physiology and chemical synthesis. The prediction of esterases substrate promiscuity level from sequence data and the molecular reasons why certain such enzymes are more promiscuous than others, remain to be elucidated. This limits the surveillance of the sequence space for esterases potentially leading to new versatile biocatalysts and new insights into their role in cellular function. Here we performed an extensive analysis of the substrate spectra of 145 phylogenetically and environmentally diverse microbial esterases, when tested with 96 diverse esters. We determined the primary factors shaping their substrate range by analyzing substrate range patterns in combination with structural analysis and protein-ligand simulations. We found a structural parameter that helps ranking (classifying) promiscuity level of esterases from sequence data at 94% accuracy. This parameter, the active site effective volume, exemplifies the topology of the catalytic environment by measuring the active site cavity volume corrected by the relative solvent accessible surface area (SASA) of the catalytic triad. Sequences encoding esterases with active site effective volumes (cavity volume/SASA) above a threshold show greater substrate spectra, which can be further extended in combination with phylogenetic data. This measure provides also a valuable tool for interrogating substrates capable of being converted. This measure, found to be transferred to phosphatases of the haloalkanoic acid dehalogenase superfamily and possibly other enzymatic systems, represents a powerful tool for low-cost bioprospecting for esterases with broad substrate ranges, in large scale sequence datasets. Title: Inactive methyl indole-3-acetic acid ester can be hydrolyzed and activated by several esterases belonging to the AtMES esterase family of Arabidopsis Yang Y, Xu R, Ma CJ, Vlot AC, Klessig DF, Pichersky E Ref: Plant Physiol, 147:1034, 2008 : PubMed ESTHER: Yang_2008_Plant.Physiol_147_1034 PubMedSearch: Yang 2008 Plant.Physiol 147 1034 PubMedID: 18467465 Gene_locus related to this paper: arath-AT4G16690, arath-MES6, arath-MES1, arath-MES19 Abstract The plant hormone auxin (indole-3-acetic acid [IAA]) is found both free and conjugated to a variety of carbohydrates, amino acids, and peptides. We have recently shown that IAA could be converted to its methyl ester (MeIAA) by the Arabidopsis (Arabidopsis thaliana) enzyme IAA carboxyl methyltransferase 1. However, the presence and function of MeIAA in vivo remains unclear. Recently, it has been shown that the tobacco (Nicotiana tabacum) protein SABP2 (salicylic acid binding protein 2) hydrolyzes methyl salicylate to salicylic acid. There are 20 homologs of SABP2 in the genome of Arabidopsis, which we have named AtMES (for methyl esterases). We tested 15 of the proteins encoded by these genes in biochemical assays with various substrates and identified several candidate MeIAA esterases that could hydrolyze MeIAA. MeIAA, like IAA, exerts inhibitory activity on the growth of wild-type roots when applied exogenously. However, the roots of Arabidopsis plants carrying T-DNA insertions in the putative MeIAA esterase gene AtMES17 (At3g10870) displayed significantly decreased sensitivity to MeIAA compared with wild-type roots while remaining as sensitive to free IAA as wild-type roots. Incubating seedlings in the presence of [(14)C]MeIAA for 30 min revealed that mes17 mutants hydrolyzed only 40% of the [(14)C]MeIAA taken up by plants, whereas wild-type plants hydrolyzed 100% of absorbed [(14)C]MeIAA. Roots of Arabidopsis plants overexpressing AtMES17 showed increased sensitivity to MeIAA but not to IAA. Additionally, mes17 plants have longer hypocotyls and display increased expression of the auxin-responsive DR5:beta-glucuronidase reporter gene, suggesting a perturbation in IAA homeostasis and/or transport. mes17-1/axr1-3 double mutant plants have the same phenotype as axr1-3, suggesting MES17 acts upstream of AXR1. The protein encoded by AtMES17 had a K(m) value of 13 microm and a K(cat) value of 0.18 s(-1) for MeIAA. AtMES17 was expressed at the highest levels in shoot apex, stem, and root of Arabidopsis. Our results demonstrate that MeIAA is an inactive form of IAA, and the manifestations of MeIAA in vivo activity are due to the action of free IAA that is generated from MeIAA upon hydrolysis by one or more plant esterases. Title: Structural and biochemical studies identify tobacco SABP2 as a methyl salicylate esterase and implicate it in plant innate immunity Forouhar F, Yang Y, Kumar D, Chen Y, Fridman E, Park SW, Chiang Y, Acton TB, Montelione GT and Tong L <2 more author(s)> Forouhar F, Yang Y, Kumar D, Chen Y, Fridman E, Park SW, Chiang Y, Acton TB, Montelione GT, Pichersky E, Klessig DF, Tong L (- 2) Ref: Proc Natl Acad Sci U S A, 102:1773, 2005 : PubMed ESTHER: Forouhar_2005_Proc.Natl.Acad.Sci.U.S.A_102_1773 PubMedSearch: Forouhar 2005 Proc.Natl.Acad.Sci.U.S.A 102 1773 PubMedID: 15668381 Gene_locus related to this paper: nicta-SABP2 Inhibitor(s) related to this paper: Salicylic-acid Abstract Salicylic acid (SA) is a critical signal for the activation of plant defense responses against pathogen infections. We recently identified SA-binding protein 2 (SABP2) from tobacco as a protein that displays high affinity for SA and plays a crucial role in the activation of systemic acquired resistance to plant pathogens. Here we report the crystal structures of SABP2, alone and in complex with SA at up to 2.1-A resolution. The structures confirm that SABP2 is a member of the alpha/beta hydrolase superfamily of enzymes, with Ser-81, His-238, and Asp-210 as the catalytic triad. SA is bound in the active site and is completely shielded from the solvent, consistent with the high affinity of this compound for SABP2. Our biochemical studies reveal that SABP2 has strong esterase activity with methyl salicylate as the substrate, and that SA is a potent product inhibitor of this catalysis. Modeling of SABP2 with MeSA in the active site is consistent with all these biochemical observations. Our results suggest that SABP2 may be required to convert MeSA to SA as part of the signal transduction pathways that activate systemic acquired resistance and perhaps local defense responses as well. 1 less
Xue R, Feng M, Chen J, Ge W, Blair MW Ref: Theor Appl Genet, :, 2021 : PubMed ESTHER: Xue_2021_Theor.Appl.Genet__ PubMedSearch: Xue 2021 Theor.Appl.Genet PubMedID: 34128089 Gene_locus related to this paper: phavu-v7cf29 Abstract Methyl esterase (MES), PvMES1, contributes to the defense response toward Fusarium wilt in common beans by regulating the salicylic acid (SA) mediated signaling pathway from phenylpropanoid synthesis and sugar metabolism as well as others. Common bean (Phaseolus vulgaris L.) is an important food legume. Fusarium wilt caused by Fusarium oxysporum f. sp. phaseoli is one of the most serious soil-borne diseases of common bean found throughout the world and affects the yield and quality of the crop. Few sources of Fusarium wilt resistance exist in legumes and most are of quantitative inheritance. In this study, we have identified a methyl esterase (MES), PvMES1, that contributes to plant defense response by regulating the salicylic acid (SA) mediated signaling pathway in response to Fusarium wilt in common beans. The result showed the role of PvMES1 in regulating SA levels in common bean and thus the SA signaling pathway and defense response mechanism in the plant. Overexpression of the PvMES1 gene enhanced Fusarium wilt resistance; while silencing of the gene caused susceptibility to the diseases. RNA-seq analysis with these transiently modified plants showed that genes related to SA level changes included the following gene ontologies: (a) phenylpropanoid synthesis; (b) sugar metabolism; and (c) interaction between host and pathogen as well as others. These key signal elements activated the defense response pathway in common bean to Fusarium wilt. Collectively, our findings indicate that PvMES1 plays a pivotal role in regulating SA biosynthesis and signaling, and increasing Fusarium wilt resistance in common bean, thus providing novel insight into the practical applications of both SA and MES genes and pathways they contribute to for developing elite crop varieties with enhanced broad-spectrum resistance to this critical disease. Title: Determinants and prediction of esterase substrate promiscuity patterns Martinez-Martinez M, Coscolin C, Santiago G, Chow J, Stogios PJ, Bargiela R, Gertler C, Navarro-Fernandez J, Bollinger A and Ferrer M <32 more author(s)> Martinez-Martinez M, Coscolin C, Santiago G, Chow J, Stogios PJ, Bargiela R, Gertler C, Navarro-Fernandez J, Bollinger A, Thies S, Mendez-Garcia C, Popovic A, Brown G, Chernikova TN, Garcia-Moyano A, Bjergah GE, Perez-Garcia P, Hai T, Del Pozo MV, Stokke R, Steen IH, Cui H, Xu X, Nocek BP, Alcaide M, Distaso M, Mesa V, Pelaez AI, Sanchez J, Buchholz PCF, Pleiss J, Fernandez-Guerra A, Glockner FO, Golyshina OV, Yakimov MM, Savchenko A, Jaeger KE, Yakunin AF, Streit WR, Golyshin PN, Guallar V, Ferrer M (- 32) Ref: ACS Chemical Biology, 13:225, 2018 : PubMed ESTHER: Martinez-Martinez_2018_ACS.Chem.Biol_13_225 PubMedSearch: Martinez-Martinez 2018 ACS.Chem.Biol 13 225 PubMedID: 29182315 Gene_locus related to this paper: 9zzzz-a0a2k8jn75, 9zzzz-a0a2k8jt94, 9zzzz-a0a0g3fj44, 9zzzz-a0a0g3fh10, 9zzzz-a0a0g3fh03, 9bact-a0a1s5qkj8, 9zzzz-a0a0g3feh5, 9zzzz-a0a0g3fkz4, 9zzzz-a0a0g3fh07, 9zzzz-a0a0g3fh34, 9zzzz-a0a0g3fh31, 9bact-KY458167, alcbs-q0vqa3, 9bact-a0a1s5qki8, 9zzzz-a0a0g3feq8, 9zzzz-a0a0g3feh8, 9zzzz-a0a0g3fh19, 9bact-KY203037, 9bact-a0a1s5ql22, 9bact-a0a1s5qm34, 9bact-KY203034, 9bact-r9qzg0, 9bact-a0a1s5qly8, 9zzzz-a0a0g3fkz8, 9zzzz-a0a0g3feg9, 9zzzz-KY203033, 9zzzz-a0a0g3fes4, 9zzzz-a0a0g3fh42, 9bact-a0a1s5qlx2, 9zzzz-KY483651, 9bact-a0a1s5qmh4, 9zzzz-KY203032, 9zzzz-EH87, 9zzzz-a0a0g3fei1, 9zzzz-a0a0g3fet2, 9zzzz-KY483647, 9zzzz-EH82, 9zzzz-a0a0g3fe15, 9bact-KY203031, 9bact-t1w006, 9zzzz-a0a0g3fet6, 9bact-KY458164, geoth-g8myf3, 9bact-a0a1s5ql04, 9gamm-a0a1y0ihk7, 9bact-a0a1s5qly6, 9bact-a0a1s5qkg4, 9bact-a0a1s5qkm4, 9gamm-s5tv80, 9gamm-a0a0c4zhg2, 9zzzz-t1b379, 9gamm-KY483646, 9bact-KY458160, 9zzzz-a0a0g3fj57, 9gamm-s5t8349, 9arch-KY203036, 9bact-KY458168, 9zzzz-a0a0g3fes0, 9zzzz-t1be47, 9bact-KY458159, 9zzzz-a0a0g3fh39, 9bact-t1vzd5, 9prot-EH41, 9bact-Lip114, alcbs-q0vt77, 9bact-a0a1s5qke6, 9bact-a0a1s5qkf3, 9prot-SRP030024, 9gamm-s5t532, 9bact-a0a1s5qkl2, 9bact-a0a1s5qkk8, 9zzzz-KY203030, 9zzzz-t1d4I7, 9prot-KY019260, 9bact-a0a1s5qm38, 9arch-KY458161, 9prot-KY010302, 9zzzz-a0a0g3fl25, 9actn-KY010298, 9gamm-s5u059, 9bact-a0a1s5qmi7, 9bact-KY010297, 9bact-KY483642, 9bact-a0a1s5qkj1, 9bact-KY010299, 9bact-KY483648, alcbs-q0vtl7, 9bact-a0a1s5qf1, 9bact-a0a1s5qkg0, 9bact-a0a0h4tgu6, 9bact-MilE3, 9bact-LAE6, 9alte-MGS-MT1, 9bact-r9qzf7, 9gamm-k0c6t6, alcbs-q0vl36, alcbs-q0vlq1, alcbs-q0vq49, bacsu-pnbae, canar-LipB, canan-lipasA, geost-lipas, marav-a1u5n0, pseps-i7k8x5, staep-GEHD, symth-q67mr3, altma-s5cfn7, cycsp-k0c2b8, alcbs-q0vlk5, 9bact-k7qe48, 9bact-MGS-M1, 9bact-MGS-M2, 9bact-a0a0b5kns5, 9zzzz-a0a0g3fej4, 9zzzz-a0a0g3fj60, 9zzzz-a0a0g3fej0, 9zzzz-a0a0g3fj64, 9bact-a0a0b5kc16, 9zzzz-a0a0g3feg6, 9zzzz-a0a0g3feu6 Abstract Esterases receive special attention because their wide distribution in biological systems and environments and their importance for physiology and chemical synthesis. The prediction of esterases substrate promiscuity level from sequence data and the molecular reasons why certain such enzymes are more promiscuous than others, remain to be elucidated. This limits the surveillance of the sequence space for esterases potentially leading to new versatile biocatalysts and new insights into their role in cellular function. Here we performed an extensive analysis of the substrate spectra of 145 phylogenetically and environmentally diverse microbial esterases, when tested with 96 diverse esters. We determined the primary factors shaping their substrate range by analyzing substrate range patterns in combination with structural analysis and protein-ligand simulations. We found a structural parameter that helps ranking (classifying) promiscuity level of esterases from sequence data at 94% accuracy. This parameter, the active site effective volume, exemplifies the topology of the catalytic environment by measuring the active site cavity volume corrected by the relative solvent accessible surface area (SASA) of the catalytic triad. Sequences encoding esterases with active site effective volumes (cavity volume/SASA) above a threshold show greater substrate spectra, which can be further extended in combination with phylogenetic data. This measure provides also a valuable tool for interrogating substrates capable of being converted. This measure, found to be transferred to phosphatases of the haloalkanoic acid dehalogenase superfamily and possibly other enzymatic systems, represents a powerful tool for low-cost bioprospecting for esterases with broad substrate ranges, in large scale sequence datasets. Title: Inactive methyl indole-3-acetic acid ester can be hydrolyzed and activated by several esterases belonging to the AtMES esterase family of Arabidopsis Yang Y, Xu R, Ma CJ, Vlot AC, Klessig DF, Pichersky E Ref: Plant Physiol, 147:1034, 2008 : PubMed ESTHER: Yang_2008_Plant.Physiol_147_1034 PubMedSearch: Yang 2008 Plant.Physiol 147 1034 PubMedID: 18467465 Gene_locus related to this paper: arath-AT4G16690, arath-MES6, arath-MES1, arath-MES19 Abstract The plant hormone auxin (indole-3-acetic acid [IAA]) is found both free and conjugated to a variety of carbohydrates, amino acids, and peptides. We have recently shown that IAA could be converted to its methyl ester (MeIAA) by the Arabidopsis (Arabidopsis thaliana) enzyme IAA carboxyl methyltransferase 1. However, the presence and function of MeIAA in vivo remains unclear. Recently, it has been shown that the tobacco (Nicotiana tabacum) protein SABP2 (salicylic acid binding protein 2) hydrolyzes methyl salicylate to salicylic acid. There are 20 homologs of SABP2 in the genome of Arabidopsis, which we have named AtMES (for methyl esterases). We tested 15 of the proteins encoded by these genes in biochemical assays with various substrates and identified several candidate MeIAA esterases that could hydrolyze MeIAA. MeIAA, like IAA, exerts inhibitory activity on the growth of wild-type roots when applied exogenously. However, the roots of Arabidopsis plants carrying T-DNA insertions in the putative MeIAA esterase gene AtMES17 (At3g10870) displayed significantly decreased sensitivity to MeIAA compared with wild-type roots while remaining as sensitive to free IAA as wild-type roots. Incubating seedlings in the presence of [(14)C]MeIAA for 30 min revealed that mes17 mutants hydrolyzed only 40% of the [(14)C]MeIAA taken up by plants, whereas wild-type plants hydrolyzed 100% of absorbed [(14)C]MeIAA. Roots of Arabidopsis plants overexpressing AtMES17 showed increased sensitivity to MeIAA but not to IAA. Additionally, mes17 plants have longer hypocotyls and display increased expression of the auxin-responsive DR5:beta-glucuronidase reporter gene, suggesting a perturbation in IAA homeostasis and/or transport. mes17-1/axr1-3 double mutant plants have the same phenotype as axr1-3, suggesting MES17 acts upstream of AXR1. The protein encoded by AtMES17 had a K(m) value of 13 microm and a K(cat) value of 0.18 s(-1) for MeIAA. AtMES17 was expressed at the highest levels in shoot apex, stem, and root of Arabidopsis. Our results demonstrate that MeIAA is an inactive form of IAA, and the manifestations of MeIAA in vivo activity are due to the action of free IAA that is generated from MeIAA upon hydrolysis by one or more plant esterases. Title: Structural and biochemical studies identify tobacco SABP2 as a methyl salicylate esterase and implicate it in plant innate immunity Forouhar F, Yang Y, Kumar D, Chen Y, Fridman E, Park SW, Chiang Y, Acton TB, Montelione GT and Tong L <2 more author(s)> Forouhar F, Yang Y, Kumar D, Chen Y, Fridman E, Park SW, Chiang Y, Acton TB, Montelione GT, Pichersky E, Klessig DF, Tong L (- 2) Ref: Proc Natl Acad Sci U S A, 102:1773, 2005 : PubMed ESTHER: Forouhar_2005_Proc.Natl.Acad.Sci.U.S.A_102_1773 PubMedSearch: Forouhar 2005 Proc.Natl.Acad.Sci.U.S.A 102 1773 PubMedID: 15668381 Gene_locus related to this paper: nicta-SABP2 Inhibitor(s) related to this paper: Salicylic-acid Abstract Salicylic acid (SA) is a critical signal for the activation of plant defense responses against pathogen infections. We recently identified SA-binding protein 2 (SABP2) from tobacco as a protein that displays high affinity for SA and plays a crucial role in the activation of systemic acquired resistance to plant pathogens. Here we report the crystal structures of SABP2, alone and in complex with SA at up to 2.1-A resolution. The structures confirm that SABP2 is a member of the alpha/beta hydrolase superfamily of enzymes, with Ser-81, His-238, and Asp-210 as the catalytic triad. SA is bound in the active site and is completely shielded from the solvent, consistent with the high affinity of this compound for SABP2. Our biochemical studies reveal that SABP2 has strong esterase activity with methyl salicylate as the substrate, and that SA is a potent product inhibitor of this catalysis. Modeling of SABP2 with MeSA in the active site is consistent with all these biochemical observations. Our results suggest that SABP2 may be required to convert MeSA to SA as part of the signal transduction pathways that activate systemic acquired resistance and perhaps local defense responses as well. |
