A horizontally acquired expansin gene increases virulence of the emerging plant pathogen Erwinia tracheiphila

AbstractAll land plants depend on proteins called ‘expansins’ that non-enzymatically loosen structural cellulose, enabling cell wall extension during normal growth. Surprisingly, expansin genes are also present – but functionally uncharacterized – in taxonomically diverse bacteria and fungi that do not produce cellulosic cell walls. Here, we find that Erwinia tracheiphila (Enterobacteriaceae), the causative agent of bacterial wilt of cucurbits, has horizontally acquired an operon with a microbial expansin (exlx) gene and a glycoside hydrolase family 5 (gh5) gene. E. tracheiphila is an unusually virulent plant pathogen that induces systemic wilt symptoms followed by plant death, and has only recently emerged into cultivated cucurbit populations in temperate Eastern North America. Plant inoculation experiments with deletion mutants show that EXLX-GH5 is a secreted virulence factor that confers efficient xylem movement and colonization ability to E. tracheiphila. Bacterial colonization of xylem blocks sap flow, inducing wilt symptoms and causing plant death. Together, these results suggest that the horizontal acquisition of the exlx-gh5 locus was likely a key step driving the recent emergence of E. tracheiphila. The increase in E. tracheiphila virulence conferred by microbial expansins, the presence of this gene in many other bacterial and fungal wilt-inducing plant pathogen species, and the amenability of microbial expansins to horizontal gene transfer suggest this gene may be an under-appreciated virulence factor in taxonomically diverse agricultural pathogens.ImportanceErwinia tracheiphila is a bacterial plant pathogen that causes a fatal wilt infection in cucurbit crop plants. Here, we report that E. tracheiphila has horizontally acquired a microbial expansin gene (exlx) adjacent to a glycoside hydrolase family 5 (gh5) gene. Expansins are predominantly associated with plants due to their essential role in loosening structural cell wall cellulose during normal growth. We find that the EXLX and GH5 proteins in E. tracheiphila function as a single complex to facilitate xylem colonization, possibly by manipulating the size of xylem structures that normally exclude the passage of bacteria. This suggests that horizontal acquisition of the exlx-gh5 locus was likely a key step in the recent emergence of E. tracheiphila as an unusually virulent plant pathogen. The presence of microbial expansin genes in diverse species of bacterial and fungal wilt-inducing pathogens suggests it may be an under-appreciated virulence factor for other microbes.

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Growth of Chitinophaga pinensis on Plant Cell Wall Glycans and Characterisation of a Glycoside Hydrolase Family 27 β-l-Arabinopyranosidase Implicated in Arabinogalactan Utilisation

PLoS ONE ◽

10.1371/journal.pone.0139932 ◽

2015 ◽

Vol 10 (10) ◽

pp. e0139932 ◽

Cited By ~ 12

Author(s):

Lauren S. McKee ◽

Harry Brumer

Keyword(s):

Cell Wall ◽

Plant Cell ◽

Glycoside Hydrolase ◽

Plant Cell Wall ◽

Glycoside Hydrolase Family ◽

Hydrolase Family

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Genome-Wide Analysis of Glycoside Hydrolase Family 35 Genes and Their Potential Roles in Cell Wall Development in Medicago truncatula

Plants ◽

10.3390/plants10081639 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1639

Author(s):

Junfeng Yang ◽

Qian Li ◽

Wenxuan Du ◽

Yu Yao ◽

Guoan Shen ◽

...

Keyword(s):

Cell Wall ◽

Medicago Truncatula ◽

Glycoside Hydrolase ◽

Expression Patterns ◽

Functional Characterization ◽

Glycoside Hydrolase Family ◽

Forage Crops ◽

Specific Expression ◽

Hydrolase Family ◽

Expression Module

Plant β-galactosidases (BGAL) function in various cell wall biogeneses and modifications, and they belong to the glycoside hydrolase family. However, the roles of BGAL family members in Medicago truncatula cell wall remodeling remain unclear. In this study, a total of 25 MtBGAL members of the glycoside hydrolase gene family 35 were identified, and they were clustered into nine sub-families. Many cis-acting elements possibly related to MeJA and abscisic acid responses were identified in the promoter region of the MtBGAL genes. Transcript analyses showed that these MtBGAL genes exhibited distinct expression patterns in various tissues and developing stem internodes. Furthermore, a stem-specific expression module associated with cell wall metabolic pathways was identified by weighted correlation network analysis (WGCNA). In particular, MtBGAL1 and MtBGAL23 within the stem-specific expression module were highly expressed in mature stems. In addition, several genes involved in lignin, cellulose, hemicellulose and pectin pathways were co-expressed with MtBGAL1 and MtBGAL23. It was also found that MtBGAL1 and MtBGAL23 were localized to the cell wall at the subcellular level, indicating their roles in the modification of cell wall metabolites in Medicago. As a whole, these results will be useful for further functional characterization and utilization of BGAL genes in cell wall modifications aiming to improve the quality of legume forage crops.

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Structural and enzymatic characterization of a glycoside hydrolase family 31 α-xylosidase from Cellvibrio japonicus involved in xyloglucan saccharification

Biochemical Journal ◽

10.1042/bj20110299 ◽

2011 ◽

Vol 436 (3) ◽

pp. 567-580 ◽

Cited By ~ 49

Author(s):

Johan Larsbrink ◽

Atsushi Izumi ◽

Farid M. Ibatullin ◽

Azadeh Nakhai ◽

Harry J. Gilbert ◽

...

Keyword(s):

Cell Wall ◽

Glycoside Hydrolase ◽

Plant Cell Wall ◽

Biomass Conversion ◽

Primary Cell Wall ◽

Glycoside Hydrolase Family ◽

Cellvibrio Japonicus ◽

Glycoside Hydrolase Family 31 ◽

Hydrolase Family

The desire for improved methods of biomass conversion into fuels and feedstocks has re-awakened interest in the enzymology of plant cell wall degradation. The complex polysaccharide xyloglucan is abundant in plant matter, where it may account for up to 20% of the total primary cell wall carbohydrates. Despite this, few studies have focused on xyloglucan saccharification, which requires a consortium of enzymes including endo-xyloglucanases, α-xylosidases, β-galactosidases and α-L-fucosidases, among others. In the present paper, we show the characterization of Xyl31A, a key α-xylosidase in xyloglucan utilization by the model Gram-negative soil saprophyte Cellvibrio japonicus. CjXyl31A exhibits high regiospecificity for the hydrolysis of XGOs (xylogluco-oligosaccharides), with a particular preference for longer substrates. Crystallographic structures of both the apo enzyme and the trapped covalent 5-fluoro-β-xylosyl-enzyme intermediate, together with docking studies with the XXXG heptasaccharide, revealed, for the first time in GH31 (glycoside hydrolase family 31), the importance of a PA14 domain insert in the recognition of longer oligosaccharides by extension of the active-site pocket. The observation that CjXyl31A was localized to the outer membrane provided support for a biological model of xyloglucan utilization by C. japonicus, in which XGOs generated by the action of a secreted endo-xyloglucanase are ultimately degraded in close proximity to the cell surface. Moreover, the present study diversifies the toolbox of glycosidases for the specific modification and saccharification of cell wall polymers for biotechnological applications.

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Xylanases of glycoside hydrolase family 30 – An overview

Biotechnology Advances ◽

10.1016/j.biotechadv.2021.107704 ◽

2021 ◽

Vol 47 ◽

pp. 107704

Author(s):

Vladimír Puchart ◽

Katarína Šuchová ◽

Peter Biely

Keyword(s):

Glycoside Hydrolase ◽

Glycoside Hydrolase Family ◽

Hydrolase Family ◽

Glycoside Hydrolase Family 30

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Modeled 3D-Structures of Proteobacterial Transglycosylases from Glycoside Hydrolase Family 17 Give Insight in Ligand Interactions Explaining Differences in Transglycosylation Products

Applied Sciences ◽

10.3390/app11094048 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4048

Author(s):

Javier A. Linares-Pastén ◽

Lilja Björk Jonsdottir ◽

Gudmundur O. Hreggvidsson ◽

Olafur H. Fridjonsson ◽

Hildegard Watzlawick ◽

...

Keyword(s):

Glycoside Hydrolase ◽

Ligand Docking ◽

Glycoside Hydrolase Family ◽

Ligand Interactions ◽

Tim Barrel ◽

Branching Point ◽

The Difference ◽

Dynamics Simulations ◽

And Function ◽

Hydrolase Family

The structures of glycoside hydrolase family 17 (GH17) catalytic modules from modular proteins in the ndvB loci in Pseudomonas aeruginosa (Glt1), P. putida (Glt3) and Bradyrhizobium diazoefficiens (previously B. japonicum) (Glt20) were modeled to shed light on reported differences between these homologous transglycosylases concerning substrate size, preferred cleavage site (from reducing end (Glt20: DP2 product) or non-reducing end (Glt1, Glt3: DP4 products)), branching (Glt20) and linkage formed (1,3-linkage in Glt1, Glt3 and 1,6-linkage in Glt20). Hybrid models were built and stability of the resulting TIM-barrel structures was supported by molecular dynamics simulations. Catalytic amino acids were identified by superimposition of GH17 structures, and function was verified by mutagenesis using Glt20 as template (i.e., E120 and E209). Ligand docking revealed six putative subsites (−4, −3, −2, −1, +1 and +2), and the conserved interacting residues suggest substrate binding in the same orientation in all three transglycosylases, despite release of the donor oligosaccharide product from either the reducing (Glt20) or non-reducing end (Glt1, Gl3). Subsites +1 and +2 are most conserved and the difference in release is likely due to changes in loop structures, leading to loss of hydrogen bonds in Glt20. Substrate docking in Glt20 indicate that presence of covalently bound donor in glycone subsites −4 to −1 creates space to accommodate acceptor oligosaccharide in alternative subsites in the catalytic cleft, promoting a branching point and formation of a 1,6-linkage. The minimum donor size of DP5, can be explained assuming preferred binding of DP4 substrates in subsite −4 to −1, preventing catalysis.

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Understanding the Polymerization Mechanism of Glycoside-Hydrolase Family 70 Glucansucrases

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)84038-3 ◽

2006 ◽

Vol 281 (42) ◽

pp. 31254-31267

Author(s):

Claire Moulis ◽

Gilles Joucla ◽

David Harrison ◽

Emeline Fabre ◽

Gabrielle Potocki-Veronese ◽

...

Keyword(s):

Glycoside Hydrolase ◽

Glycoside Hydrolase Family ◽

Polymerization Mechanism ◽

Hydrolase Family

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Endo-fucoidan hydrolases from glycoside hydrolase family 107 (GH107) display structural and mechanistic similarities to α-l-fucosidases from GH29

Journal of Biological Chemistry ◽

10.1074/jbc.ra118.005134 ◽

2018 ◽

Vol 293 (47) ◽

pp. 18296-18308 ◽

Cited By ~ 10

Author(s):

Chelsea Vickers ◽

Feng Liu ◽

Kento Abe ◽

Orly Salama-Alber ◽

Meredith Jenkins ◽

...

Keyword(s):

Glycoside Hydrolase ◽

Biological Activities ◽

Bacterial Species ◽

Structural Data ◽

Side Chain ◽

Glycoside Hydrolase Family ◽

X Ray Crystallography ◽

Catalytic Mechanisms ◽

Thickening Agents ◽

Hydrolase Family

Fucoidans are chemically complex and highly heterogeneous sulfated marine fucans from brown macro algae. Possessing a variety of physicochemical and biological activities, fucoidans are used as gelling and thickening agents in the food industry and have anticoagulant, antiviral, antitumor, antibacterial, and immune activities. Although fucoidan-depolymerizing enzymes have been identified, the molecular basis of their activity on these chemically complex polysaccharides remains largely uninvestigated. In this study, we focused on three glycoside hydrolase family 107 (GH107) enzymes: MfFcnA and two newly identified members, P5AFcnA and P19DFcnA, from a bacterial species of the genus Psychromonas. Using carbohydrate-PAGE, we show that P5AFcnA and P19DFcnA are active on fucoidans that differ from those depolymerized by MfFcnA, revealing differential substrate specificity within the GH107 family. Using a combination of X-ray crystallography and NMR analyses, we further show that GH107 family enzymes share features of their structures and catalytic mechanisms with GH29 α-l-fucosidases. However, we found that GH107 enzymes have the distinction of utilizing a histidine side chain as the proposed acid/base catalyst in its retaining mechanism. Further interpretation of the structural data indicated that the active-site architectures within this family are highly variable, likely reflecting the specificity of GH107 enzymes for different fucoidan substructures. Together, these findings begin to illuminate the molecular details underpinning the biological processing of fucoidans.

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Characterization of Glycoside Hydrolase Family 5 Proteins in Schizosaccharomyces pombe

Eukaryotic Cell ◽

10.1128/ec.00187-10 ◽

2010 ◽

Vol 9 (11) ◽

pp. 1650-1660 ◽

Cited By ~ 11

Author(s):

Encarnación Dueñas-Santero ◽

Ana Belén Martín-Cuadrado ◽

Thierry Fontaine ◽

Jean-Paul Latgé ◽

Francisco del Rey ◽

...

Keyword(s):

Cell Wall ◽

Schizosaccharomyces Pombe ◽

Protein Characterization ◽

Wall Material ◽

Glycoside Hydrolase Family ◽

Content Type ◽

Hydrolysis Of ◽

Controlled Hydrolysis ◽

Hydrolase Family

ABSTRACT In yeast, enzymes with β-glucanase activity are thought to be necessary in morphogenetic events that require controlled hydrolysis of the cell wall. Comparison of the sequence of the Saccharomyces cerevisiae exo-β(1,3)-glucanase Exg1 with the Schizosaccharomyces pombe genome allowed the identification of three genes that were named exg1 + (locus SPBC1105.05), exg2 + (SPAC12B10.11), and exg3 + (SPBC2D10.05). The three proteins have different localizations: Exg1 is secreted to the periplasmic space, Exg2 is a membrane protein, and Exg3 is a cytoplasmic protein. Characterization of the biochemical activity of the proteins indicated that Exg1 and Exg3 are active only against β(1,6)-glucans while no activity was detected for Exg2. Interestingly, Exg1 cleaves the glucans with an endohydrolytic mode of action. exg1 + showed periodic expression during the cell cycle, with a maximum coinciding with the septation process, and its expression was dependent on the transcription factor Sep1. The Exg1 protein localizes to the septum region in a pattern that was different from that of the endo-β(1,3)-glucanase Eng1. Overexpression of Exg2 resulted in an increase in cell wall material at the poles and in the septum, but the putative catalytic activity of the protein was not required for this effect.

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