2024-03-28T19:15:38Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/682762022-11-17T02:08:08Zhdl_2115_20046hdl_2115_138Biochemical Properties and Atomic Resolution Structure of a Proteolytically Processed β-Mannanase from Cellulolytic Streptomyces sp. SirexAA-ETakasuka, Taichi E.Acheson, Justin F.Bianchetti, Christopher M.Prom, Ben M.Bergeman, Lai F.Book, Adam J.Currie, Cameron R.Fox, Brian G.open access© 2014 Takasuka et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Creative Commons Attribution 4.0 International439Abstract: β-mannanase SACTE_2347 from cellulolytic Streptomyces sp. SirexAA-E is abundantly secreted into the culture medium during growth on cellulosic materials. The enzyme is composed of domains from the glycoside hydrolase family 5 (GH5), fibronectin type-III (Fn3), and carbohydrate binding module family 2 (CBM2). After secretion, the enzyme is proteolyzed into three different, catalytically active variants with masses of 53, 42 and 34 kDa corresponding to the intact protein, loss of the CBM2 domain, or loss of both the Fn3 and CBM2 domains. The three variants had identical N-termini starting with Ala51, and the positions of specific proteolytic reactions in the linker sequences separating the three domains were identified. To conduct biochemical and structural characterizations, the natural proteolytic variants were reproduced by cloning and heterologously expressed in Escherichia coli. Each SACTE_2347 variant hydrolyzed only β-1,4 mannosidic linkages, and also reacted with pure mannans containing partial galactosyl- and/or glucosyl substitutions. Examination of the X-ray crystal structure of the GH5 domain of SACTE_2347 suggests that two loops adjacent to the active site channel, which have differences in position and length relative to other closely related mannanases, play a role in producing the observed substrate selectivity.The Public Library of Science (PLoS)2014-04-07engjournal articleVoRhttp://hdl.handle.net/2115/68276https://doi.org/10.1371/journal.pone.00941661932-6203PLoS ONE94e94166https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/68276/1/journal.pone.0094166.pdfapplication/pdf1.32 MB2014-04-07