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770 a.a.
Key reference
DOI no: 10.1016/j.jmb.2007.04.035 J Mol Biol 370:53-62 (2007) PubMed id: 17498741
The Structural Basis for the Exo-mode of Action in GH74 Oligoxyloglucan Reducing End-specific Cellobiohydrolase. K.Yaoi, H.Kondo, A.Hiyoshi, N.Noro, H.Sugimoto, S.Tsuda, Y.Mitsuishi, K.Miyazaki. ABSTRACT
Oligoxyloglucan reducing end-specific cellobiohydrolase (OXG-RCBH) is a unique exo-beta-1,4-glucanase that belongs to glycoside hydrolase family 74. The enzyme recognizes the reducing end of xyloglucan oligosaccharides and releases two glucosyl residue segments from the reducing end of the main chain. Previously, we reported that OXG-RCBH consists of two seven-bladed beta-propeller domains. There is a large cleft between the two domains, and a unique loop encloses one side of the active site cleft. Here, we report the X-ray crystal structure of the OXG-RCBH-substrate complex determined to a resolution of 2.4 A. The substrate bound to the cleft, and its reducing end was arranged near the loop region that is believed to impart OXG-RCBH with its activity. We constructed a deletion mutant of the loop region and conducted a detailed analysis. A deletion mutant of the loop region showed endo-activity with altered substrate recognition. More specifically, cleavage occurred randomly instead of at specific sites, most likely due to the misalignment of the substrate within the subsite. We believe that the loop imparts unique substrate specificity with exo-mode hydrolysis in OXG-RCBH.
Selected figure(s)
Figure 1.
Figure 2.
Figure 2. The stereo view of the active site around −2 to +2. (a) OXG-RCBH with the substrate, XXXG. (b) Clostridium thermocellum Xgh74A with the substrate LGXX (PDB code: 2CN3). The substrates are colored yellow.
The above figures are reprinted by permission from Elsevier: J Mol Biol (2007, 370, 53-62) copyright 2007. Figures were selected by the author.
Literature references that cite this PDB file's key reference
PubMed id Reference
19193638 A.Ochiai, T.Itoh, B.Mikami, W.Hashimoto, and K.Murata (2009).
Structural determinants responsible for substrate recognition and mode of action in family 11 polysaccharide lyases.J Biol Chem, 284, 10181-10189.
PDB codes: 2zux 2zuy
19682300 K.Yaoi, H.Kondo, A.Hiyoshi, N.Noro, H.Sugimoto, S.Tsuda, and K.Miyazaki (2009).
The crystal structure of a xyloglucan-specific endo-beta-1,4-glucanase from Geotrichum sp. M128 xyloglucanase reveals a key amino acid residue for substrate specificity.FEBS J, 276, 5094-5100.
17922847 T.Ishida, K.Yaoi, A.Hiyoshi, K.Igarashi, and M.Samejima (2007).
Substrate recognition by glycoside hydrolase family 74 xyloglucanase from the basidiomycete Phanerochaete chrysosporium.FEBS J, 274, 5727-5736. 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 codes are shown on the right.
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