Dataset Information

Diversity of Pectin Rhamnogalacturonan I Rhamnosyltransferases in Glycosyltransferase Family 106.

ABSTRACT: Rhamnogalacturonan I (RG-I) comprises approximately one quarter of the pectin molecules in land plants, and the backbone of RG-I consists of a repeating sequence of [2)-?-L-Rha(1-4)-?-D-GalUA(1-] disaccharide. Four Arabidopsis thaliana genes encoding RG-I rhamnosyltransferases (AtRRT1 to AtRRT4), which synthesize the disaccharide repeats, have been identified in the glycosyltransferase family (GT106). However, the functional role of RG-I in plant cell walls and the evolutional history of RRTs remains to be clarified. Here, we characterized the sole ortholog of AtRRT1-AtRRT4 in liverwort, Marchantia polymorpha, namely, MpRRT1. MpRRT1 had RRT activity and genetically complemented the AtRRT1-deficient mutant phenotype in A. thaliana. However, the MpRRT1-deficient M. polymorpha mutants showed no prominent morphological changes and only an approximate 20% reduction in rhamnose content in the cell wall fraction compared to that in wild-type plants, suggesting the existence of other RRT gene(s) in the M. polymorpha genome. As expected, we detected RRT activities in other GT106 family proteins such as those encoded by MpRRT3 in M. polymorpha and FRB1/AtRRT8 in A. thaliana, the deficient mutant of which affects cell adhesion. Our results show that RRT genes are more redundant and diverse in GT106 than previously thought.

SUBMITTER: Wachananawat B

PROVIDER: S-EPMC7343896 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Diversity of Pectin Rhamnogalacturonan I Rhamnosyltransferases in Glycosyltransferase Family 106.

Wachananawat Bussarin B Kuroha Takeshi T Takenaka Yuto Y Kajiura Hiroyuki H Naramoto Satoshi S Yokoyama Ryusuke R Ishizaki Kimitsune K Nishitani Kazuhiko K Ishimizu Takeshi T

Frontiers in plant science 20200702

Rhamnogalacturonan I (RG-I) comprises approximately one quarter of the pectin molecules in land plants, and the backbone of RG-I consists of a repeating sequence of [2)-α-L-Rha(1-4)-α-D-GalUA(1-] disaccharide. Four <i>Arabidopsis thaliana</i> genes encoding RG-I rhamnosyltransferases (AtRRT1 to AtRRT4), which synthesize the disaccharide repeats, have been identified in the glycosyltransferase family (GT106). However, the functional role of RG-I in plant cell walls and the evolutional history of ...[more]

PMID: 32714362

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Project description:Pseudomonas cellulosa is an aerobic bacterium that synthesizes an extensive array of modular cellulases and hemicellulases, which have a modular architecture consisting of catalytic domains and distinct non-catalytic carbohydrate-binding modules (CBMs). To investigate whether the main-chain-cleaving pectinases from this bacterium also have a modular structure, a library of P. cellulosa genomic DNA, constructed in lambdaZAPII, was screened for pectinase-encoding sequences. A recombinant phage that attacked arabinan, galactan and rhamnogalacturonan was isolated. The encoded enzyme, designated Rgl11A, had a modular structure comprising an N-terminal domain that exhibited homology to Bacillus and Streptomyces proteins of unknown function, a middle domain that exhibited sequence identity to fibronectin-3 domains, and a C-terminal domain that was homologous to family 2a CBMs. Expression of the three modules of the Pseudomonas protein in Escherichia coli showed that its C-terminal module was a functional cellulose-binding domain, and the N-terminal module consisted of a catalytic domain that hydrolysed rhamnogalacturonan-containing substrates. The activity of Rgl11A against apple- and potato-derived rhamnogalacturonan substrates indicated that the enzyme had a strong preference for rhamnogalacturonans that contained galactose side chains, and which were not esterified. The enzyme had an absolute requirement for calcium, a high optimum pH, and catalysis was associated with an increase in absorbance at 235 nm, indicating that glycosidic bond cleavage was mediated via a beta-elimination mechanism. These data indicate that Rgl11A is a rhamnogalacturonan lyase and, together with the homologous Bacillus and Streptomyces proteins, comprise a new family of polysaccharide lyases. The presence of a family 2a CBM in Rgl11A, and in a P. cellulosa pectate lyase described in the accompanying paper [Brown, Mallen, Charnock, Davies and Black (2001) Biochem. J. 355, 155-165] suggests that the capacity to bind cellulose plays an important role in the activity of main-chain-cleaving Pseudomonas pectinases, in addition to cellulases and hemicellulases.

Dataset Information

Diversity of Pectin Rhamnogalacturonan I Rhamnosyltransferases in Glycosyltransferase Family 106.

Publications

Diversity of Pectin Rhamnogalacturonan I Rhamnosyltransferases in Glycosyltransferase Family 106.

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