Identification of a novel xanthan-binding module of a multi-modular Cohnella sp. xanthanase.

Autor:	Han R; Chair of Microbiology, School of Life Sciences, Technical University of Munich, Freising, Germany., Baudrexl M; Chair of Microbiology, School of Life Sciences, Technical University of Munich, Freising, Germany., Ludwig C; Bavarian Center for Biomolecular Mass Spectrometry (BayBioMS), School of Life Sciences, Technical University of Munich, Freising, Germany., Berezina OV; National Research Centre 'Kurchatov Institute', Moscow, Russia., Rykov SV; National Research Centre 'Kurchatov Institute', Moscow, Russia., Liebl W; Chair of Microbiology, School of Life Sciences, Technical University of Munich, Freising, Germany.
Jazyk:	angličtina
Zdroj:	Frontiers in microbiology [Front Microbiol] 2024 Mar 26; Vol. 15, pp. 1386552. Date of Electronic Publication: 2024 Mar 26 (Print Publication: 2024).
DOI:	10.3389/fmicb.2024.1386552
Abstrakt:	A new strain of xanthan-degrading bacteria identified as Cohnella sp. has been isolated from a xanthan thickener for food production. The strain was able to utilize xanthan as the only carbon source and to reduce the viscosity of xanthan-containing medium during cultivation. Comparative analysis of the secretomes of Cohnella sp. after growth on different media led to the identification of a xanthanase designated as Csp Xan9, which was isolated after recombinant production in Escherichia coli . Csp Xan9 could efficiently degrade the β-1,4-glucan backbone of xanthan after previous removal of pyruvylated mannose residues from the ends of the native xanthan side chains by xanthan lyase treatment (XLT-xanthan). Compared with xanthanase from Paenibacillus nanensis , xanthanase Csp Xan9 had a different module composition at the N- and C-terminal ends. The main putative oligosaccharides released from XLT-xanthan by Csp Xan9 cleavage were tetrasaccharides and octasaccharides. To explore the functions of the N- and C-terminal regions of the enzyme, truncated variants lacking some of the non-catalytic modules ( Csp Xan9-C, Csp Xan9-N, Csp Xan9-C-N) were produced. Enzyme assays with the purified deletion derivatives, which all contained the catalytic glycoside hydrolase family 9 (GH9) module, demonstrated substantially reduced specific activity on XLT-xanthan of Csp Xan9-C-N compared with full-length Csp Xan9. The C-terminal module of Csp Xan9 was found to represent a novel carbohydrate-binding module of family CBM66 with binding affinity for XLT-xanthan, as was shown by native affinity polyacrylamide gel electrophoresis in the presence of various polysaccharides. The only previously known binding function of a CBM66 member is exo-type binding to the non-reducing fructose ends of the β-fructan polysaccharides inulin and levan. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2024 Han, Baudrexl, Ludwig, Berezina, Rykov and Liebl.)
Databáze:	MEDLINE
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