2d8l
From Proteopedia
Crystal Structure of Unsaturated Rhamnogalacturonyl Hydrolase in complex with dGlcA-GalNAc
Structural highlights
Function[URHG2_BACSU] Catalyzes the hydrolysis of unsaturated rhamnogalacturonan disaccharide to yield unsaturated D-galacturonic acid and L-rhamnose. It cannot act on unsaturated glucuronyl hydrolase (UGL) substrates containing unsaturated D-glucuronic acid at the non-reducing terminus, although the active pockets of YesR and UGL are very similar.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedYteR, a hypothetical protein with unknown functions, is derived from Bacillus subtilis strain 168 and has an overall structure similar to that of bacterial unsaturated glucuronyl hydrolase (UGL), although it exhibits little amino acid sequence identity with UGL. UGL releases unsaturated glucuronic acid from glycosaminoglycan treated with glycosaminoglycan lyases. The amino acid sequence of YteR shows a significant homology (26% identity) with the hypothetical protein YesR also from B. subtilis strain 168. To clarify the intrinsic functions of YteR and YesR, both proteins were overexpressed in Escherichia coli, purified, and characterized. Based on their gene arrangements in genome and enzyme properties, YteR and YesR were found to constitute a novel enzyme activity, "unsaturated rhamnogalacturonyl hydrolase," classified as new glycoside hydrolase family 105. This enzyme acts specifically on unsaturated rhamnogalacturonan (RG) obtained from RG type-I treated with RG lyases and releases an unsaturated galacturonic acid. The crystal structure of YteR complexed with unsaturated chondroitin disaccharide (UGL substrate) was obtained and compared to the structure of UGL complexed with the same disaccharide. The UGL substrate is sterically hindered with the active pocket of YteR. The protruding loop of YteR prevents the UGL substrate from being bound effectively. The most likely candidate catalytic residues for general acid/base are Asp143 in YteR and Asp135 in YesR. This is supported by three-dimensional structural and site-directed mutagenesis studies. These findings provide molecular insights into novel enzyme catalysis and sequential reaction mechanisms involved in RG-I depolymerization by bacteria. A novel glycoside hydrolase family 105: the structure of family 105 unsaturated rhamnogalacturonyl hydrolase complexed with a disaccharide in comparison with family 88 enzyme complexed with the disaccharide.,Itoh T, Ochiai A, Mikami B, Hashimoto W, Murata K J Mol Biol. 2006 Jul 14;360(3):573-85. Epub 2006 May 9. PMID:16781735[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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