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376 a.a.
_NI
Key reference
DOI no: 10.1074/jbc.M413693200 J Biol Chem 280:17180-17186 (2005) PubMed id: 15718242
Structural basis for the specificity of the reducing end xylose-releasing exo-oligoxylanase from Bacillus halodurans C-125. S.Fushinobu, M.Hidaka, Y.Honda, T.Wakagi, H.Shoun, M.Kitaoka. ABSTRACT
Reducing end xylose-releasing exo-oligoxylanase from Bacillus halodurans C-125 (Rex) hydrolyzes xylooligosaccharides whose degree of polymerization is greater than or equal to 3, releasing the xylose unit at the reducing end. It is a unique exo-type glycoside hydrolase that recognizes the xylose unit at the reducing end in a very strict manner, even discriminating the beta-anomeric hydroxyl configuration from the alpha-anomer or 1-deoxyxylose. We have determined the crystal structures of Rex in unliganded and complex forms at 1.35-2.20-A resolution and revealed the structural aspects of its three subsites ranging from -2 to +1. The structure of Rex was compared with those of endo-type enzymes in glycoside hydrolase subfamily 8a (GH-8a). The catalytic machinery of Rex is basically conserved with other GH-8a enzymes. However, subsite +2 is blocked by a barrier formed by a kink in the loop before helix alpha10. His-319 in this loop forms a direct hydrogen bond with the beta-hydroxyl of xylose at subsite +1, contributing to the specific recognition of anomers at the reducing end.
Selected figure(s)
Figure 2.
FIG. 2. Ribbon diagrams of the GH-8a enzymes. The catalytic residues, ligand molecules, and metal ions are shown as black sticks, a ball-and-stick model, and spheres, respectively. a, side view of the (/
Figure 5.
FIG. 5. Schematic drawing of the active sites in the WT-xylose (a) and E70A-xylobiose (b) structures.The above figures are reprinted by permission from the ASBMB: J Biol Chem (2005, 280, 17180-17186) copyright 2005. Figures were selected by an automated process.
Literature references that cite this PDB file's key reference
PubMed id Reference
19103919 M.Fukuda, S.Watanabe, J.Kaneko, Y.Itoh, and Y.Kamio (2009).
The membrane lipoprotein LppX of Paenibacillus sp. strain W-61 serves as a molecular chaperone for xylanase of glycoside hydrolase family 11 during secretion across the cytoplasmic membrane.J Bacteriol, 191, 1641-1649.
17586675 S.Lagaert, S.Van Campenhout, A.Pollet, T.M.Bourgois, J.A.Delcour, C.M.Courtin, and G.Volckaert (2007).
Recombinant expression and characterization of a reducing-end xylose-releasing exo-oligoxylanase from Bifidobacterium adolescentis.Appl Environ Microbiol, 73, 5374-5377.
16794344 N.N.Aronson, and B.A.Halloran (2006).
Optimum substrate size and specific anomer requirements for the reducing-end glycoside hydrolase di-N-acetylchitobiase.Biosci Biotechnol Biochem, 70, 1537-1541.
16804941 Y.Yasutake, S.Kawano, K.Tajima, M.Yao, Y.Satoh, M.Munekata, and I.Tanaka (2006).
Structural characterization of the Acetobacter xylinum endo-beta-1,4-glucanase CMCax required for cellulose biosynthesis.Proteins, 64, 1069-1077.
PDB code: 1wzz The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time. Where a reference describes a PDB structure, the PDB code is shown on the right.
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