Applicability of endochitinase of Flavobacterium johnsoniae with transglycosylation activity in generating long-chain chitooligosaccharides.

Autor: Vaikuntapu PR; Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500046, Telangana, India., Mallakuntla MK; Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500046, Telangana, India., Das SN; Department of Botany, Indira Gandhi National Tribal University, Amarkantak 484887, Madhya Pradesh, India., Bhuvanachandra B; Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500046, Telangana, India., Ramakrishna B; Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500046, Telangana, India., Nadendla SR; Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500046, Telangana, India., Podile AR; Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500046, Telangana, India. Electronic address: podilerao@gmail.com.
Jazyk: angličtina
Zdroj: International journal of biological macromolecules [Int J Biol Macromol] 2018 Oct 01; Vol. 117, pp. 62-71. Date of Electronic Publication: 2018 May 22.
DOI: 10.1016/j.ijbiomac.2018.05.129
Abstrakt: Chitin and its derivatives are used for a variety of applications. Flavobacterium johnsoniae UW101 is an aerobic Gram-negative bacterium. Genome analysis of F. johnsoniae UW101 revealed the presence of 10 glycoside hydrolases (GHs) that may degrade or modify chitin. The gene encoding chitinase B (FjchiB), which encodes a single catalytic GH18 domain has been cloned and heterologously expressed in Escherichia coli. FjChiB was optimally active in 50 mM sodium citrate buffer (pH 6.0) at 40 °C. FjChiB was salt-tolerant and catalytically versatile, with substrate specificity towards 75% DDA (degree of de-acetylation) chitosan, followed by colloidal chitin. Chitotetraose (DP4) was the shortest of the oligomeric substrates used by FjChiB. The K m and V max values of FjChiB for colloidal chitin were 49.38 mg/ml and 11.2 nanokat mg -1 , respectively. The overall catalytic efficiency (k c at /K m ) of FjChiB was 1.40 × 10 3  mg -1  ml s -1 . FjChiB exhibited transglycosylation (TG) with chitopentaose (DP5) and chitohexaose (DP6) substrates. The TG by FjChiB was fine-tuned by introducing a tryptophan (G106W) and asparagine (D148N) in the highly conserved catalytic groove and catalytic center, respectively. Hydrolytic products profile and homology modelling indicated that FjChiB is an endochitinase that holds promise for the conversion of chitin into useful products through both TG and/or hydrolysis.
(Copyright © 2018 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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