Saccharomyces cerevisiae chitin biosynthesis activation by N-acetylchitooses depends on size and structure of chito-oligosaccharides

Abstract

BackgroundTo explore chitin synthesis initiation, the effect of addition of exogenous oligosaccharides on in vitro chitin synthesis was studied. Oligosaccharides of various natures and lengths were added to a chitin synthase assay performed on a Saccharomyces cerevisiae membrane fraction.FindingsN-acetylchito-tetra, -penta and -octaoses resulted in 11 to 25% [14C]-GlcNAc incorporation into [14C]-chitin, corresponding to an increase in the initial velocity. The activation appeared specific to N-acetylchitooses as it was not observed with oligosaccharides in other series, such as beta-(1,4), beta-(1,3) or alpha-(1,6) glucooligosaccharides.ConclusionsThe effect induced by the N-acetylchitooses was a saturable phenomenon and did not interfere with free GlcNAc and trypsin which are two known activators of yeast chitin synthase activity in vitro. The magnitude of the activation was dependent on both oligosaccharide concentration and oligosaccharide size.

Architecture and Biosynthesis of the Saccharomyces cerevisiae Cell Wall

“…NodC did not use short chito--oligosaccharides as GlcNAc acceptor from UDP--GlcNAc (Kamst et al 1999), nor did purified Chs1 elongate chitotetraose into insoluble chitin in the presence of UDP--GlcNAc ). However, inclusion of 1 mM GlcNAc 5 and GlcNAc 8 in assays of membrane preparations expressing predominantly Chs1 led to about a 1.25--fold increase in incorporation of GlcNAc into chitin from UDP--GlcNAc in the presence of free GlcNAc (Becker et al 2011), suggesting a primer function for longer chito--oligosaccharides. The initiation and early elongation steps in chitin synthesis clearly still need to be defined.…”

2-Acylamido Analogues of N-Acetylglucosamine Prime Formation of Chitin Oligosaccharides by Yeast Chitin Synthase 2

“…Preexisting chitin chains presumably serve as acceptors for further GlcNAc addition, but short chitin oligosaccharides (COs) do not, because NodC did not use short COs as GlcNAc acceptor from UDP-GlcNAc ( 17 ), nor did a purified yeast CS (Chs1) elongate chitotetraose into chitin in the presence of UDP-GlcNAc ( 9 ). However, it has been proposed that longer COs can serve as primers ( 18 ).…”

Insights into the structure and function of membrane-integrated processive glycosyltransferases

“…CHS1 is responsible for only 10% of the in vivo chitin pool, but accounts for most of the chitin synthase activity recovered in vitro [21]. Interestingly, this activity is enhanced in the presence of NAG as well as chitooligosaccharides, which may prime chitin biosynthesis [22]. …”