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Chitinase Chit62J4 Essential for Chitin Processing by Human Microbiome Bacterium Clostridium paraputrificum J4

Authors :
Jarmila Dušková
Jan Dohnálek
Petr Kolenko
Karla Fejfarová
Petr Novák
J. Šimůnek
Tereza Skálová
Galina Tishchenko
Source :
Molecules, Vol 26, Iss 5978, p 5978 (2021), Molecules, Volume 26, Issue 19
Publication Year :
2021
Publisher :
MDPI AG, 2021.

Abstract

Commensal bacterium Clostridium paraputrificum J4 produces several extracellular chitinolytic enzymes including a 62 kDa chitinase Chit62J4 active toward 4-nitrophenyl N,N′-diacetyl-β-d-chitobioside (pNGG). We characterized the crude enzyme from bacterial culture fluid, recombinant enzyme rChit62J4, and its catalytic domain rChit62J4cat. This major chitinase, securing nutrition of the bacterium in the human intestinal tract when supplied with chitin, has a pH optimum of 5.5 and processes pNGG with Km = 0.24 mM and kcat = 30.0 s−1. Sequence comparison of the amino acid sequence of Chit62J4, determined during bacterial genome sequencing, characterizes the enzyme as a family 18 glycosyl hydrolase with a four-domain structure. The catalytic domain has the typical TIM barrel structure and the accessory domains—2x Fn3/Big3 and a carbohydrate binding module—that likely supports enzyme activity on chitin fibers. The catalytic domain is highly homologous to a single-domain chitinase of Bacillus cereus NCTU2. However, the catalytic profiles significantly differ between the two enzymes despite almost identical catalytic sites. The shift of pI and pH optimum of the commensal enzyme toward acidic values compared to the soil bacterium is the likely environmental adaptation that provides C. paraputrificum J4 a competitive advantage over other commensal bacteria.

Details

ISSN :
14203049
Volume :
26
Database :
OpenAIRE
Journal :
Molecules
Accession number :
edsair.doi.dedup.....1136c72059d806a7b84c3bd0e238e28f
Full Text :
https://doi.org/10.3390/molecules26195978