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Crystallographic structure and molecular dynamics simulations of the major endoglucanase from Xanthomonas campestris pv. campestris shed light on its oligosaccharide products release pattern. Int J Biol Macromol 2019; 136:493-502. [PMID: 31216447 DOI: 10.1016/j.ijbiomac.2019.06.107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 06/09/2019] [Accepted: 06/15/2019] [Indexed: 12/23/2022]
Abstract
Cellulases are essential enzymatic components for the transformation of plant biomass into fuels, renewable materials and green chemicals. Here, we determined the crystal structure, pattern of hydrolysis products release, and conducted molecular dynamics simulations of the major endoglucanase from the Xanthomonas campestris pv. campestris (XccCel5A). XccCel5A has a TIM barrel fold with the catalytic site centrally placed in a binding groove surrounded by aromatic side chains. Molecular dynamics simulations show that productive position of the substrate is secured by a network of hydrogen bonds in the four main subsites, which differ in details from homologous structures. Capillary zone electrophoresis and computational studies reveal XccCel5A can act both as endoglucanase and licheninase, but there are preferable arrangements of substrate regarding β-1,3 and β-1,4 bonds within the binding cleft which are related to the enzymatic efficiency.
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Xu H, Chen H, Shen Y, Du L, Chou SH, Liu H, Qian G, Liu F. Direct Regulation of Extracellular Chitinase Production by the Transcription Factor LeClp in Lysobacter enzymogenes OH11. PHYTOPATHOLOGY 2016; 106:971-7. [PMID: 27385597 DOI: 10.1094/phyto-01-16-0001-r] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Lysobacter enzymogenes is a gram-negative bacterial biological control agent that produces abundant extracellular enzymes capable of degrading the cell walls of fungal pathogens. In strain OH11, an isolate from China, the global regulator LeClp controls the production of extracellular chitinase by regulating the transcription of the chitinase-encoding gene chiA. Using a combination of bioinformatic, genetic, and biochemical methods, we show that LeClp regulates chiA transcription by directly binding to the chiA promoter region. Although LeClp appears to be important in this role, it is not the sole regulator of chiA transcription. Furthermore, the sequence analysis of putative LeClp binding sites indicated that the LeClp homolog could be involved in the regulation of extracellular chitinase production in diverse Lysobacter spp. by a mechanism similar to that in L. enzymogenes. Our findings present new insights into the molecular mechanism of LeClp in controlling extracellular chitinase activity, providing a fundamental road to elucidate how LeClp regulates the production of other extracellular lytic enzymes in L. enzymogenes.
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Affiliation(s)
- Huiyong Xu
- First, second, sixth, seventh, and eighth authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P.R. China and Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education; third author: Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, 250100 Jinan, P.R. China; fourth author: Department of Chemistry, University of Nebraska-Lincoln, Lincoln 68588; fifth author: Institute of Biochemistry, and NCHU Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, ROC; and eighth author: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, P.R. China
| | - Hongfu Chen
- First, second, sixth, seventh, and eighth authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P.R. China and Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education; third author: Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, 250100 Jinan, P.R. China; fourth author: Department of Chemistry, University of Nebraska-Lincoln, Lincoln 68588; fifth author: Institute of Biochemistry, and NCHU Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, ROC; and eighth author: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, P.R. China
| | - Yuemao Shen
- First, second, sixth, seventh, and eighth authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P.R. China and Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education; third author: Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, 250100 Jinan, P.R. China; fourth author: Department of Chemistry, University of Nebraska-Lincoln, Lincoln 68588; fifth author: Institute of Biochemistry, and NCHU Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, ROC; and eighth author: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, P.R. China
| | - Liangcheng Du
- First, second, sixth, seventh, and eighth authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P.R. China and Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education; third author: Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, 250100 Jinan, P.R. China; fourth author: Department of Chemistry, University of Nebraska-Lincoln, Lincoln 68588; fifth author: Institute of Biochemistry, and NCHU Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, ROC; and eighth author: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, P.R. China
| | - Shan-Ho Chou
- First, second, sixth, seventh, and eighth authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P.R. China and Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education; third author: Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, 250100 Jinan, P.R. China; fourth author: Department of Chemistry, University of Nebraska-Lincoln, Lincoln 68588; fifth author: Institute of Biochemistry, and NCHU Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, ROC; and eighth author: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, P.R. China
| | - Hongxia Liu
- First, second, sixth, seventh, and eighth authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P.R. China and Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education; third author: Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, 250100 Jinan, P.R. China; fourth author: Department of Chemistry, University of Nebraska-Lincoln, Lincoln 68588; fifth author: Institute of Biochemistry, and NCHU Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, ROC; and eighth author: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, P.R. China
| | - Guoliang Qian
- First, second, sixth, seventh, and eighth authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P.R. China and Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education; third author: Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, 250100 Jinan, P.R. China; fourth author: Department of Chemistry, University of Nebraska-Lincoln, Lincoln 68588; fifth author: Institute of Biochemistry, and NCHU Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, ROC; and eighth author: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, P.R. China
| | - Fengquan Liu
- First, second, sixth, seventh, and eighth authors: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, P.R. China and Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education; third author: Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, 250100 Jinan, P.R. China; fourth author: Department of Chemistry, University of Nebraska-Lincoln, Lincoln 68588; fifth author: Institute of Biochemistry, and NCHU Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, ROC; and eighth author: Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, P.R. China
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Biophysical and biochemical studies of a major endoglucanase secreted by Xanthomonas campestris pv. campestris. Enzyme Microb Technol 2016; 91:1-7. [PMID: 27444323 DOI: 10.1016/j.enzmictec.2016.05.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 05/14/2016] [Accepted: 05/20/2016] [Indexed: 12/23/2022]
Abstract
Endoglucanases are the main cellulolytic enzymes secreted by the bacterium Xanthomonas campestris pv. campestris (Xcc). The major endoglucanase exported by this bacterium into an external milieu is an enzyme XccCel5A, which belongs to GH5 family subfamily 1 and is encoded by the gene engXCA. We purified XccCel5A using ammonium sulfate precipitation followed by size exclusion chromatography and identified it by zymogram analysis. Circular dichroism and fluorescence spectroscopy studies showed that XccCel5A is stable in a wide pH range and up to about 55°C and denatures at the higher temperatures. The optimal conditions for enzyme activity were identified as T=45°C and pH=7.0. Under the optimum conditions the catalytic efficiency (kcat/KM) of the enzyme was determined as 5.16×10(4)s(-1)M(-1) using carboxymethylcellulose (CMC) as a substrate. Our SAXS studies revealed extended tadpole-shape molecular assembly, typical for cellulases, and allowed to determine an overall shape of the enzyme and a relative position of the catalytic and cellulose binding domains.
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Rosseto FR, Puhl AC, Andrade MO, Polikarpov I. Crystallization and preliminary diffraction analysis of the catalytic domain of major extracellular endoglucanase from Xanthomonas campestris pv. campestris. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:137-40. [PMID: 23385754 PMCID: PMC3564615 DOI: 10.1107/s1744309112051408] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 12/20/2012] [Indexed: 11/10/2022]
Abstract
Cellulases, such as endoglucanases, exoglucanases and β-glucosidases, are important enzymes used in the process of enzymatic hydrolysis of plant biomass. The bacteria Xanthomonas campestris pv. campestris expresses a large number of hydrolases and the major endoglucanase (XccEG), a member of glycoside hydrolase family 5 (GH5), is the most strongly secreted extracellularly. In this work, the native XccEG was purified from the extracellular extract and crystallization assays were performed on its catalytic domain. A complete data set was collected on an in-house X-ray source. The crystal diffracted to 2.7 Å resolution and belonged to space group C2, with unit-cell parameters a = 174.66, b = 141.53, c = 108.00 Å, β = 110.49°. The Matthews coefficient suggests a solvent content of 70.1% and the presence of four protein subunits in the asymmetric unit.
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Affiliation(s)
- Flávio R. Rosseto
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador Saocarlense 400, São Carlos-SP 13560-970, Brazil
| | - Ana C. Puhl
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador Saocarlense 400, São Carlos-SP 13560-970, Brazil
| | - Maxuel O. Andrade
- Instituto de Química, Universidade de São Paulo, Avenida Prof. Lineu Prestes 748, Bloco Química Fina, Sala 10, Cidade Universitária, São Paulo-SP 05508-000, Brazil
| | - Igor Polikarpov
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador Saocarlense 400, São Carlos-SP 13560-970, Brazil
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The cyclic nucleotide monophosphate domain of Xanthomonas campestris global regulator Clp defines a new class of cyclic di-GMP effectors. J Bacteriol 2009; 192:1020-9. [PMID: 20008070 DOI: 10.1128/jb.01253-09] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The widely conserved second messenger cyclic diguanosine monophosphate (c-di-GMP) plays a key role in quorum-sensing (QS)-dependent production of virulence factors in Xanthomonas campestris pv. campestris. The detection of QS diffusible signal factor (DSF) by the sensor RpfC leads to the activation of response regulator RpfG, which activates virulence gene expression by degrading c-di-GMP. Here, we show that a global regulator in the X. campestris pv. campestris QS regulatory pathway, Clp, is a c-di-GMP effector. c-di-GMP specifically binds to Clp with high affinity and induces allosteric conformational changes that abolish the interaction between Clp and its target gene promoter. Clp is similar to the cyclic AMP (cAMP) binding proteins Crp and Vfr and contains a conserved cyclic nucleotide monophosphate (cNMP) binding domain. Using site-directed mutagenesis, we found that the cNMP binding domain of Clp contains a glutamic acid residue (E99) that is essential for c-di-GMP binding. Substituting the residue with serine (E99S) resulted in decreased sensitivity to changes in the intracellular c-di-GMP level and attenuated bacterial virulence. These data establish the direct role of Clp in the response to fluctuating c-di-GMP levels and depict a novel mechanism by which QS links the second messenger with the X. campestris pv. campestris virulence regulon.
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Thowthampitak J, Shaffer BT, Prathuangwong S, Loper JE. Role of rpfF in virulence and exoenzyme production of Xanthomonas axonopodis pv. glycines, the causal agent of bacterial pustule of soybean. PHYTOPATHOLOGY 2008; 98:1252-60. [PMID: 18999999 DOI: 10.1094/phyto-98-12-1252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Ten strains of Xanthomonas axonopodis pv. glycines, the causal agent of bacterial pustule of soybean, which were isolated from various soybean growing regions of Thailand, produced an extracellular diffusible factor (DSF) related to a well-characterized quorum sensing molecule produced by other Xanthomonas spp. Genomic DNA of the 10 strains of X. axonopodis pv. glycines contained rpfF, a gene encoding for the biosynthesis of the DSF in X. campestris pv. campestris. The rpfF gene from one strain of X. axonopodis pv. glycines was fully sequenced, and the 289 aa product is closely related to RpfF of other Xanthomonas spp. (95 to 98% identical). Three independently generated rpfF mutants of X. axonopodis pv. glycines strain No12-2 were defective in the production of a DSF, as expected if rpfF encodes for DSF biosynthesis in X. axonopodis pv. glycines. The rpfF mutants of X. axonopodis pv. glycines exhibited reduced virulence on soybean and produced less than wild-type levels of extracellular polysaccharide and the extracellular enzymes carboxylmethylcellulase, protease, endo-beta-1,4-mannanase, and pectate lyase. Transcripts for three genes that encode for the extracellular enzymes protease, endoglucanase, and pectate lyase were at lower abundance in an rpfF mutant than in the parental strain of X. axonopodis pv. glycines. These results indicate that X. axonopodis pv. glycines produces a diffusible signal related to the DSF of X. campestris pv. campestris, which contributes to virulence and exoenzyme production by this phytopathogenic bacterium.
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Affiliation(s)
- J Thowthampitak
- Department of Plant Pathology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
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Chung WJ, Shu HY, Lu CY, Wu CY, Tseng YH, Tsai SF, Lin CH. Qualitative and comparative proteomic analysis ofXanthomonas campestris pv.campestris 17. Proteomics 2007; 7:2047-58. [PMID: 17566974 DOI: 10.1002/pmic.200600647] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The bacterium Xanthomonas campestris pathovar campestris (XCC) 17 is a local isolate that causes crucifer black rot disease in Taiwan. In this study, its proteome was separated using 2-DE and the well-resolved proteins were excised, trypsin digested, and analyzed by MS. Over 400 protein spots were analyzed and 281 proteins were identified by searching the MS or MS/MS spectra against the proteome database of the closely related XCC ATCC 33913. Functional categorization of the identified proteins matched 141 (50%) proteins to 81 metabolic pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. In addition, we performed a comparative proteome analysis of the pathogenic strain 17 and an avirulent strain 11A to reveal the virulence-related proteins. We detected 22 up-regulated proteins in strain 17 including the degrading enzymes EngXCA, HtrA, and PepA, which had been shown to have a role in pathogenesis in other bacteria, and an anti-host defense protein, Ohr. Thus, further functional studies of these up-regulated proteins with respect to their roles in XCC pathogenicity are suggested.
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Affiliation(s)
- Wei-Jen Chung
- Sequencing Core, Genome Research Center, National Yang-Ming University, Taipei, Taiwan
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Blanvillain S, Meyer D, Boulanger A, Lautier M, Guynet C, Denancé N, Vasse J, Lauber E, Arlat M. Plant carbohydrate scavenging through tonB-dependent receptors: a feature shared by phytopathogenic and aquatic bacteria. PLoS One 2007; 2:e224. [PMID: 17311090 PMCID: PMC1790865 DOI: 10.1371/journal.pone.0000224] [Citation(s) in RCA: 243] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Accepted: 01/26/2007] [Indexed: 01/12/2023] Open
Abstract
TonB-dependent receptors (TBDRs) are outer membrane proteins mainly known for the active transport of iron siderophore complexes in Gram-negative bacteria. Analysis of the genome of the phytopathogenic bacterium Xanthomonas campestris pv. campestris (Xcc), predicts 72 TBDRs. Such an overrepresentation is common in Xanthomonas species but is limited to only a small number of bacteria. Here, we show that one Xcc TBDR transports sucrose with a very high affinity, suggesting that it might be a sucrose scavenger. This TBDR acts with an inner membrane transporter, an amylosucrase and a regulator to utilize sucrose, thus defining a new type of carbohydrate utilization locus, named CUT locus, involving a TBDR for the transport of substrate across the outer membrane. This sucrose CUT locus is required for full pathogenicity on Arabidopsis, showing its importance for the adaptation to host plants. A systematic analysis of Xcc TBDR genes and a genome context survey suggested that several Xcc TBDRs belong to other CUT loci involved in the utilization of various plant carbohydrates. Interestingly, several Xcc TBDRs and CUT loci are conserved in aquatic bacteria such as Caulobacter crescentus, Colwellia psychrerythraea, Saccharophagus degradans, Shewanella spp., Sphingomonas spp. or Pseudoalteromonas spp., which share the ability to degrade a wide variety of complex carbohydrates and display TBDR overrepresentation. We therefore propose that TBDR overrepresentation and the presence of CUT loci designate the ability to scavenge carbohydrates. Thus CUT loci, which seem to participate to the adaptation of phytopathogenic bacteria to their host plants, might also play a very important role in the biogeochemical cycling of plant-derived nutrients in marine environments. Moreover, the TBDRs and CUT loci identified in this study are clearly different from those characterized in the human gut symbiont Bacteroides thetaiotaomicron, which allow glycan foraging, suggesting a convergent evolution of TBDRs in Proteobacteria and Bacteroidetes.
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Affiliation(s)
- Servane Blanvillain
- Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique (CNRS)/Institut National de la Recherche Agronomique (INRA) UMR2594/441, Castanet-Tolosan, France
| | - Damien Meyer
- Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique (CNRS)/Institut National de la Recherche Agronomique (INRA) UMR2594/441, Castanet-Tolosan, France
| | - Alice Boulanger
- Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique (CNRS)/Institut National de la Recherche Agronomique (INRA) UMR2594/441, Castanet-Tolosan, France
| | - Martine Lautier
- Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique (CNRS)/Institut National de la Recherche Agronomique (INRA) UMR2594/441, Castanet-Tolosan, France
- Université Paul Sabatier, Toulouse III, Toulouse, France
| | - Catherine Guynet
- Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique (CNRS)/Institut National de la Recherche Agronomique (INRA) UMR2594/441, Castanet-Tolosan, France
| | - Nicolas Denancé
- Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique (CNRS)/Institut National de la Recherche Agronomique (INRA) UMR2594/441, Castanet-Tolosan, France
| | - Jacques Vasse
- Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique (CNRS)/Institut National de la Recherche Agronomique (INRA) UMR2594/441, Castanet-Tolosan, France
| | - Emmanuelle Lauber
- Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique (CNRS)/Institut National de la Recherche Agronomique (INRA) UMR2594/441, Castanet-Tolosan, France
- * To whom correspondence should be addressed. E-mail: (EL); (MA)
| | - Matthieu Arlat
- Laboratoire des Interactions Plantes-Microorganismes, Centre National de la Recherche Scientifique (CNRS)/Institut National de la Recherche Agronomique (INRA) UMR2594/441, Castanet-Tolosan, France
- Université Paul Sabatier, Toulouse III, Toulouse, France
- * To whom correspondence should be addressed. E-mail: (EL); (MA)
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Hsiao YM, Liao HY, Lee MC, Yang TC, Tseng YH. Clp upregulates transcription of engA gene encoding a virulence factor in Xanthomonas campestris by direct binding to the upstream tandem Clp sites. FEBS Lett 2005; 579:3525-33. [PMID: 15955530 DOI: 10.1016/j.febslet.2005.05.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Revised: 04/22/2005] [Accepted: 05/03/2005] [Indexed: 10/25/2022]
Abstract
In Xanthomonas campestris, the causative agent of black rot in crucifers, the endoglucanase level is greatly decreased in the mutant deficient in Clp, a homologue of cyclic AMP receptor protein (CRP). It is established that Clp has the same DNA binding specificity as CRP at positions 5, 6, and 7 (GTG motif) of the DNA half site. In this study, the engA transcription initiation site was determined by the 5' RACE method, and two consensus Clp-binding sites, site I and site II centered at -69.5 and -42.5, respectively, were located. Transcriptional fusion assays indicated that Clp greatly activates engA transcription. Site-directed mutagenesis indicated that position 5 of GTG motif in site II is essential for both DNA-protein complex formation in electrophoretic mobility shift assays and engA transcription in vivo. In addition, mutation at position 5 of site I drastically reduces the promoter activity, indicating that binding of Clp to site I exerts a synergistic effect on the transcription activation by site II. engA appears to be the first X. campestris gene known to be activated by Clp via a direct binding to the promoter.
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Affiliation(s)
- Yi-Min Hsiao
- Institute of Medical Biotechnology, Chungtai Institute of Health Sciences and Technology, Taichung 406, Taiwan, ROC
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Abstract
Bacteria belonging to the genus Xanthomonas are important pathogens of many plants, and their virulence appears to be due primarily to secreted and surface compounds that could increase host nutrient loss, or avoid or suppress unfavorable conditions in the host. Type II and III secretory pathways are essential for virulence. Some individual extracellular enzymes (type II-secretion dependent) affect final bacterial population levels, whereas some avirulence gene products (type III-secretion dependent) affect virulence by altering host metabolism. Avr proteins, probably secreted via a pilus, can also be recognized by host resistance gene products. Virulence is also associated with bacterial surface polysaccharides, which may help to avoid host defense responses, and regulatory gene systems, which can control virulence gene expression.
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Affiliation(s)
- J W Chan
- Department of Environmental Biology, University of Guelph, Guelph, Ont. N1G 2W1, Canada
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Jahr H, Dreier J, Meletzus D, Bahro R, Eichenlaub R. The endo-beta-1,4-glucanase CelA of Clavibacter michiganensis subsp. michiganensis is a pathogenicity determinant required for induction of bacterial wilt of tomato. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2000; 13:703-714. [PMID: 10875331 DOI: 10.1094/mpmi.2000.13.7.703] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The phytopathogenic bacterium Clavibacter michiganensis subsp. michiganensis NCPPB382, which causes bacterial wilt and canker of tomato, harbors two plasmids, pCM1 (27.35 kb) and pCM2 (72 kb), encoding genes involved in virulence (D. Meletzus, A. Bermpohl, J. Dreier, and R. Eichenlaub, 1993, J. Bacteriol. 175:2131-2136; J. Dreier, D. Meletzus, and R. Eichenlaub, 1997, Mol. Plant-Microbe Interact. 10:195-206). The region of pCM1 carrying the endoglucanase gene celA was mapped by deletion analysis and complementation. RNA hybridization identified a 2.4-knt (kilonucleotide) transcript of the celA structural gene and the transcriptional initiation site was mapped. The celA gene encodes CelA, a protein of 78 kDa (746 amino acids) with similarity to endo-beta-1,4-glucanases of family A1 cellulases. CelA has a three-domain structure with a catalytic domain, a type IIa-like cellulose-binding domain, and a C-terminal domain. We present evidence that CelA plays a major role in pathogenicity, since wilt induction capability is obtained by endoglucanase expression in plasmid-free, nonvirulent strains and by complementation of the CelA- gene-replacement mutant CMM-H4 with the wild-type celA gene.
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Affiliation(s)
- H Jahr
- Universität Bielefeld, Fakultät für Biologie, Gentechnologie/Mikrobiologie, Germany
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Izu H, Izumi Y, Kurome Y, Sano M, Kondo A, Kato I, Ito M. Molecular cloning, expression, and sequence analysis of the endoglycoceramidase II gene from Rhodococcus species strain M-777. J Biol Chem 1997; 272:19846-50. [PMID: 9242646 DOI: 10.1074/jbc.272.32.19846] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Endoglycoceramidase (EGCase (EC 3.2.1.123)) is a hydrolase that hydrolyzes the linkage between the oligosaccharide and ceramide of various glycosphingolipids. This paper describes the molecular cloning and expression of EGCase II, one of the isoforms of EGCases. The gene encoding EGCase II was obtained by screening of a genomic DNA library from Rhodococcus sp. strain M-777 constructed in pUC19 with oligonucleotide probes deduced from a partial amino acid sequence of the enzyme protein. Recombinant Escherichia coli cells in which the EGCase II gene was expressed produced 14 units of the enzyme per liter of culture medium but did not produce sphingomyelinase. Recombinant EGCase II was a functioning enzyme with substrate specificity identical to that of the wild-type enzyme. Sequence analysis showed the presence of an open reading frame of 1470 base pairs encoding 490 amino acids. The N-terminal region of the deduced amino acid sequence had the general pattern of signal peptides of secreted prokaryotic proteins. Interestingly, the consensus sequence in the active site region of the endo-1,4-beta-glucanase family A was found in the amino acid sequence of EGCase II.
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Affiliation(s)
- H Izu
- Biotechnology Research Laboratories, Takara Shuzo Co., Ltd., Seta 3-4-1, Otsu, Shiga 520-21, Japan
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Kuhad RC, Singh A, Eriksson KE. Microorganisms and enzymes involved in the degradation of plant fiber cell walls. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 1997; 57:45-125. [PMID: 9204751 DOI: 10.1007/bfb0102072] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
One of natures most important biological processes is the degradation of lignocellulosic materials to carbon dioxide, water and humic substances. This implies possibilities to use biotechnology in the pulp and paper industry and consequently, the use of microorganisms and their enzymes to replace or supplement chemical methods is gaining interest. This chapter describes the structure of wood and the main wood components, cellulose, hemicelluloses and lignins. The enzyme and enzyme mechanisms used by fungi and bacteria to modify and degrade these components are described in detail. Techniques for how to assay for these enzyme activities are also described. The possibilities for biotechnology in the pulp and paper industry and other fiber utilizing industries based on these enzymes are discussed.
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Affiliation(s)
- R C Kuhad
- Department of Microbiology, University of Delhi South Campus, New Delhi, India
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14
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Sakon J, Adney WS, Himmel ME, Thomas SR, Karplus PA. Crystal structure of thermostable family 5 endocellulase E1 from Acidothermus cellulolyticus in complex with cellotetraose. Biochemistry 1996; 35:10648-60. [PMID: 8718854 DOI: 10.1021/bi9604439] [Citation(s) in RCA: 199] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The crystal structure of the catalytic domain of the thermostable endocellulase E1 from Acidothermus cellulolyticus in complex with cellotetraose has been solved by multiple isomorphous replacement and refined at 2.4 A resolution to an R-factor of 0.18 (Rfree = 0.24). E1cd is a member of the 4/7 superfamily of hydrolases, and as expected, its structure is an (alpha/beta)8 barrel, which constitutes a prototype for family 5-subfamily 1 cellulases. The cellotetraose molecule binds in a manner consistent with the expected Michaelis complex for the glycosylation half-reaction and reveals that all eight residues conserved in family 5 enzymes are involved in recognition of the glycosyl group attacked during cleavage. Whereas only three residues are conserved in the whole 4/7 superfamily (the Asn/Glu duo and the Glu from which the name is derived), structural comparisons show that all eight residues conserved in family 5 have functional equivalents in the other 4/7 superfamily members, strengthening the case that mechanistic details are conserved throughout the superfamily. On the basis of the structure, a detailed sequence of physical steps of the cleavage mechanism is proposed. A close approach of two key glutamate residues provides an elegant mechanism for the shift in the pKa of the acid/base for the glycosylation and deglycosylation half-reactions. Finally, purely structural based comparisons are used to show that significant differences exist in structural similarity scores resulting from different methods and suggest that caution should be exercised in interpreting such results in terms of implied evolutional relationships.
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Affiliation(s)
- J Sakon
- Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853, USA
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15
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Abe JI, Shibata Y, Fujisue M, Hizukuri S. Expression of periplasmic alpha-amylase of Xanthomonas campestris K-11151 in Escherichia coli and its action on maltose. MICROBIOLOGY (READING, ENGLAND) 1996; 142 ( Pt 6):1505-1512. [PMID: 8704990 DOI: 10.1099/13500872-142-6-1505] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A gene encoding the periplasmic alpha-amylase of Xanthomonas campestris K-11151 was cloned into Escherichia coli using pUC19 as a vector. An ORF of 1578 bp was deduced to be the amylase structural gene. The primary structure of the enzyme had little identity with other alpha-amylases, except with the enzyme from Bacillus megaterium. The enzyme was expressed in E. coli from the lac promoter of pUC19 and was found to be transported to the periplasmic space. The expressed enzyme showed the same thermal stability, optimum temperature and substrate specificity as the enzyme from X. campestris. The enzyme formed maltotetraose, but not 6(1)- nor 6(2)-maltosyl-maltose, from maltose by the reverse reaction, and the tetraose was then hydrolysed to maltotriose and glucose. The addition of maltotriose enhanced the production of glucose from maltose. In addition, maltose was formed by the condensation of glucose by the enzyme. Thus, the periplasmic alpha-amylase of X. campestris was shown to produce glucose from maltose by hydrolysing maltotetraose and possibly higher maltooligosaccharides, which were the products of a condensation reaction, as a major pathway, and by direct hydrolysis of maltose as a minor pathway.
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Affiliation(s)
- Jun-Ichi Abe
- Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Korimoto-1 21-24, Kagoshima 890, Japan
| | - Yuko Shibata
- Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Korimoto-1 21-24, Kagoshima 890, Japan
| | - Mami Fujisue
- Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Korimoto-1 21-24, Kagoshima 890, Japan
| | - Susumu Hizukuri
- Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Korimoto-1 21-24, Kagoshima 890, Japan
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16
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Geelen D, van Montagu M, Holsters M. Cloning of an Azorhizobium caulinodans endoglucanase gene and analysis of its role in symbiosis. Appl Environ Microbiol 1995; 61:3304-10. [PMID: 7574641 PMCID: PMC167611 DOI: 10.1128/aem.61.9.3304-3310.1995] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Azorhizobium caulinodans ORS571, a symbiont of the tropical leguminous plant Sesbania rostrata, showed low, constitutive levels of endoglucanase (Egl) activity. A clone carrying the gene responsible for this phenotype was isolated via introduction of a genomic library into the wild-type strain and screening for transconjugants with enhanced Egl activity. By subcloning and expression in Escherichia coli, the Egl phenotype was allocated to a 3-kb EcoRI-BamHI fragment. However, sequence analysis showed the egl gene to be much larger, consisting of an open reading frame of 1,836 amino acids. Within the deduced polypeptide, three kinds of putative domains were identified: a catalytic domain, two cellulose-binding domains, and an eightfold reiterated motif. The catalytic domain belongs to the family A of cellulases. A C-terminal stretch of 100 amino acids was similar to family II cellulose-binding domains. A second copy of this domain occurred near the middle of the polypeptide, flanked by reiterated motifs. ORS571 mutants carrying a Tn5 insertion in the egl gene had lost the Egl activity. These mutants as well as Egl-overproducing strains showed a normal nodulation behavior, indistinguishable from wild-type nodulation on Sesbania rostrata under laboratory conditions.
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Affiliation(s)
- D Geelen
- Laboratorium voor Genetica, Universiteit Gent, Belgium
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17
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Lemesle-Varloot L, Ojasoo T, Mornon JP, Raynaud JP. A model for the determination of the 3D-spatial distribution of the functions of the hormone-binding domain of receptors that bind 3-keto-4-ene steroids. J Steroid Biochem Mol Biol 1992; 41:369-88. [PMID: 1562512 DOI: 10.1016/0960-0760(92)90363-n] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A method of comparing the hydrophobic clusters of proteins (hydrophobic cluster analysis, HCA) has revealed that the 3D-folding pattern of the hormone-binding domain (HBD) of steroid hormone receptors (SHRs) may have an unexpectedly high degree of analogy with the known 3D-crystal structures of proteins belonging to the serine proteinase inhibitor (SERPIN) superfamily, e.g. alpha 1-antitrypsin and ovalbumin. The present paper briefly reviews some of the biochemical evidence that supports the structural validity of the SERPIN model and shows how the model can be used to establish hypothetical 3D-locations for functions attributed to different amino-acids or peptide sequences of the HBD: i.e. heat-shock protein binding, transcription activation, phosphorylation, steroid binding, but also ATP-binding. Indeed, the model has enabled the identification of a Rossmann-fold in SHRs that might bind ATP. Visualization of all these functions should help to interpret the chain of concerted events induced by steroid binding.
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Affiliation(s)
- L Lemesle-Varloot
- Laboratoire de Minéralogie-Cristallographie, C.N.R.S. URA 09, Universités Paris, France
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18
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Fujino T, Ohmiya K. Nucleotide sequence of an endo-1,4-β-glucanase gene (celA) from Clostridium josui. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/0922-338x(92)90189-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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Henrissat B. A classification of glycosyl hydrolases based on amino acid sequence similarities. Biochem J 1991; 280 ( Pt 2):309-16. [PMID: 1747104 PMCID: PMC1130547 DOI: 10.1042/bj2800309] [Citation(s) in RCA: 2209] [Impact Index Per Article: 66.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The amino acid sequences of 301 glycosyl hydrolases and related enzymes have been compared. A total of 291 sequences corresponding to 39 EC entries could be classified into 35 families. Only ten sequences (less than 5% of the sample) could not be assigned to any family. With the sequences available for this analysis, 18 families were found to be monospecific (containing only one EC number) and 17 were found to be polyspecific (containing at least two EC numbers). Implications on the folding characteristics and mechanism of action of these enzymes and on the evolution of carbohydrate metabolism are discussed. With the steady increase in sequence and structural data, it is suggested that the enzyme classification system should perhaps be revised.
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Affiliation(s)
- B Henrissat
- Centre de Recherches sur les Macromolécules Végétales, C.N.R.S., Grenoble, France
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20
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Knoop V, Staskawicz B, Bonas U. Expression of the avirulence gene avrBs3 from Xanthomonas campestris pv. vesicatoria is not under the control of hrp genes and is independent of plant factors. J Bacteriol 1991; 173:7142-50. [PMID: 1938914 PMCID: PMC209220 DOI: 10.1128/jb.173.22.7142-7150.1991] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The avirulence gene avrBs3 from Xanthomonas campestris pv. vesicatoria pepper race 1 is responsible for the induction of a race-specific hypersensitive reaction in resistant pepper cultivars. A DNA region of 3.7 kb, containing several open reading frames and an internal repetitive region, was shown previously to be necessary for avirulence activity (U. Bonas, R. E. Stall, and B. Staskawicz, Mol. Gen. Genet. 218:127-136, 1989). The promoter of avrBs3 was identified by using gene fusions to beta-glucuronidase. Also, we mapped the transcription start site and showed that the avrBs3 gene is expressed constitutively in cells grown in minimal or complex medium and in planta. Polyclonal antibodies raised against a fusion protein produced in Escherichia coli allowed the identification of a 122-kDa protein in X. campestris pv. vesicatoria cells expressing the avrBs3 gene. The antibody is specific for AvrBs3 in X. campestris pv. vesicatoria cells but also recognizes homologous proteins in other pathovars of X. campestris. We found that AvrBs3 is localized intracellularly in X. campestris pv. vesicatoria and is mainly in the soluble fraction. The effect of mutations in the hrp gene cluster on the function of AvrBs3 was examined. Expression of AvrBs3 in X. campestris pv. vesicatoria grown in minimal or complex medium is independent of the hrp gene cluster that determines pathogenicity and hypersensitivity to X. campestris pv. vesicatoria. In the plant, however, the hrp genes are required for elicitation of a race-specific resistance response.
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Affiliation(s)
- V Knoop
- Institut für Genbiologische Forschung Berlin GmbH, Germany
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21
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Dums F, Dow JM, Daniels MJ. Structural characterization of protein secretion genes of the bacterial phytopathogen Xanthomonas campestris pathovar campestris: relatedness to secretion systems of other gram-negative bacteria. MOLECULAR & GENERAL GENETICS : MGG 1991; 229:357-64. [PMID: 1944223 DOI: 10.1007/bf00267456] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The nucleotide sequence was determined of a 5.3 kb region of the Xanthomonas campestris pathovar campestris genome carrying a gene cluster encoding protein secretion and pathogenicity functions. A putative promoter sequence and five open reading frames (ORF) which may be part of an operon were revealed. The five predicted primary translation products comprise 531, 390, 147, 169 and 138 amino acids with Mr values of 58,854, 42,299, 15,548, 18,214 and 15,108 respectively. A sixth, partial ORF is also present. Between ORF1 and ORF2 is a sequence of unknown function showing 7 bp duplications. The deduced amino acid sequence of ORF1 is related to the Klebsiella pneumoniae PulE protein, to the Bacillus subtilis ComG ORF1 and to the Agrobacterium tumefaciens VirB ORF11 products. In addition, the deduced amino acid sequence of ORF2 showed homology to the PulF and to the ComG ORF2 products. The proteins encoded by ORF3, 4 and 5 showed amino acid homology to PulG, H and I products respectively. The proteins encoded by ORF2, 3, 4 and 5 showed significant hydrophobic domains which may represent membrane-spanning regions. By contrast the protein encoded by ORF1 was largely hydrophilic and had two putative nucleoside triphosphate binding sites.
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Affiliation(s)
- F Dums
- John Innes Institute, Norwich, UK
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22
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Shen H, Schmuck M, Pilz I, Gilkes N, Kilburn D, Miller R, Warren R. Deletion of the linker connecting the catalytic and cellulose-binding domains of endoglucanase A (CenA) of Cellulomonas fimi alters its conformation and catalytic activity. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)99167-2] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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23
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Gilkes NR, Henrissat B, Kilburn DG, Miller RC, Warren RA. Domains in microbial beta-1, 4-glycanases: sequence conservation, function, and enzyme families. Microbiol Rev 1991; 55:303-15. [PMID: 1886523 PMCID: PMC372816 DOI: 10.1128/mr.55.2.303-315.1991] [Citation(s) in RCA: 421] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Several types of domain occur in beta-1, 4-glycanases. The best characterized of these are the catalytic domains and the cellulose-binding domains. The domains may be joined by linker sequences rich in proline or hydroxyamino acids or both. Some of the enzymes contain repeated sequences up to 150 amino acids in length. The enzymes can be grouped into families on the basis of sequence similarities between the catalytic domains. There are sequence similarities between the cellulose-binding domains, of which two types have been identified, and also between some domains of unknown function. The beta-1, 4-glycanases appear to have arisen by the shuffling of a relatively small number of progenitor sequences.
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Affiliation(s)
- N R Gilkes
- Department of Microbiology, University of British Columbia, Vancouver, Canada
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24
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Tang JL, Liu YN, Barber CE, Dow JM, Wootton JC, Daniels MJ. Genetic and molecular analysis of a cluster of rpf genes involved in positive regulation of synthesis of extracellular enzymes and polysaccharide in Xanthomonas campestris pathovar campestris. MOLECULAR & GENERAL GENETICS : MGG 1991; 226:409-17. [PMID: 1645442 DOI: 10.1007/bf00260653] [Citation(s) in RCA: 211] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The cosmid clone pIJ3020 containing DNA from the plant pathogenic bacterium Xanthomonas campestris pathovar campestris has previously been shown to complement a non-pathogenic mutant defective in synthesis of extracellular enzymes. The DNA cloned in pIJ3020 was analysed by mutagenesis with Tn5 and Tn5lac and by nucleotide sequencing. The results indicate that this region of the genome contains a cluster of genes, mutation in any of which results in failure of the enzymes and extracellular polysaccharide to be synthesized. The designation rpf (regulation of pathogenicity factors) is proposed for these genes. The nucleotide sequence of one gene (rpfC) predicts a protein product with homology to conserved domains of both sensor and regulator proteins of prokaryotic two-component regulatory systems, which are usually involved in regulating gene expression in response to environmental stimuli.
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Affiliation(s)
- J L Tang
- Sainsbury Laboratory, John Innes Centre for Plant Science Research, Norwich, UK
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25
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Tang JL, Gough CL, Daniels MJ. Cloning of genes involved in negative regulation of production of extracellular enzymes and polysaccharide of Xanthomonas campestris pathovar campestris. MOLECULAR & GENERAL GENETICS : MGG 1990; 222:157-60. [PMID: 1700268 DOI: 10.1007/bf00283038] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A recombinant plasmid pIJ3079 contains DNA sequences from Xanthomonas campestris pv campestris involved in coordinate negative regulation of production of the extracellular enzymes protease, endoglucanase, amylase and polygalacturonate lyase, and extracellular polysaccharide (EPS). Wild-type bacteria harbouring pIJ3079 and therefore carrying extra copies of the gene(s) therein showed reduced enzyme and EPS production and reduced aggressiveness to plants. Localised Tn5 mutagenesis of the corresponding region of the genome gave mutants producing higher levels of enzymes and EPS than the wild type, suggesting that the gene(s) may negatively regulate production in the normal cell. Enzyme and EPS production in the mutants was still dependent on previously characterised positive regulatory genes.
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Affiliation(s)
- J L Tang
- Sainsbury Laboratory, John Innes Institute, Norwich, UK
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26
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Osbourn AE, Clarke BR, Stevens BJ, Daniels MJ. Use of oligonucleotide probes to identify members of two-component regulatory systems in Xanthomonas campestris pathovar campestris. MOLECULAR & GENERAL GENETICS : MGG 1990; 222:145-51. [PMID: 2233675 DOI: 10.1007/bf00283036] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Two-component regulatory systems comprising a sensor and a regulator protein, both with highly conserved amino acid domains, and commonly genetically linked, have been described in a range of bacterial species and are involved in sensing environmental stimuli. We used two oligonucleotide probes matching the postulated coding regions for domains of sensor and regulator proteins respectively in Xanthomonas campestris pathovar campestris (Xcc) to identify possible two-component regulatory systems in Xcc. Two different fragments of Xcc DNA with homology to both of these probes were cloned. The DNA sequence of part of one of these fragments encompassed a potential open reading frame (ORF), the predicted amino acid sequence of which had extensive homology with regulator proteins of two-component regulatory systems. Analysis of the predicted amino acid sequence for the 3' end of an adjacent ORF revealed a very high level of homology with the C-terminal end of sensor proteins. Strains of Xcc with Tn5-induced mutations in the regulator gene were affected in extracellular polysaccharide production, and also in resistance to salt and chloramphenicol. No effects of mutation in the second clone were observed.
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Affiliation(s)
- A E Osbourn
- Sainsbury Laboratory, John Innes Institute, Norwich, UK
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