X-Message-Number: 17035 Date: Fri, 20 Jul 2001 09:12:50 -0700 (PDT) From: Doug Skrecky <> Subject: glucosylglycerol looks interesting as a potential additive <1> of <2> Title Uptake and use of the osmoprotective compounds trehalose, glucosylglycerol, and sucrose by the cyanobacterium Synechocystis sp. PCC6803. Source Archives of Microbiology. 167(2-3):112-8, 1997 Feb-Mar. Abstract Accumulation of exogenously supplied osmoprotective compounds was analyzed in the cyanobacterium Synechocystis sp. PCC6803, which synthesizes glucosylglycerol as the principal osmoprotective compound. Glucosylglycerol and trehalose were accumulated to high levels and protected cells of a mutant unable to synthesize glucosylglycerol against the deleterious effects of salt stress. In the wild-type, uptake of trehalose repressed the synthesis of glucosylglycerol and caused metabolic conversion of originally accumulated glucosylglycerol. Trehalose cannot be synthesized by Synechocystis and was not or only insignificantly metabolized. Sucrose, which can be synthesized in low quantities by Synechocystis, was also taken up, as indicated by its disappearance from the medium. Sucrose was not accumulated to high levels, probably due to a sucrose-degrading activity found in cells adapted to both low- and high-salt conditions. Despite its low intracellular concentration, sucrose showed a weak osmoprotective effect in salt-shocked cells of a mutant unable to synthesize glucosylglycerol. <2> Title Active transport of glucosylglycerol is involved in salt adaptation of the cyanobacterium Synechocystis sp. strain PCC 6803. Source Microbiology. 142 ( Pt 7):1725-32, 1996 Jul. Abstract An active-transport system for the osmoprotective compound glucosylglycerol (GG) was found in the cyanobacterium Synechocystis sp. strain PCC 6803. Uptake assays with 14C-labelled GG showed that the GG transport was enhanced in cells adapted to increasing concentrations of NaCl. Kinetic studies indicated a Michaelis-Menten relationship. The uptake of GG was energy dependent and occurred against a steep concentration gradient. It was inhibited by uncouplers as well as by a combination of darkness and KCN. The affinity of the transporter seems to be restricted to osmoprotective compounds of cyanobacteria; from a variety of compounds tested only sucrose and trehalose competed with GG for uptake. A salt-sensitive mutant of Synechocystis 6803 unable to synthesize GG could be complemented to salt resistance by exogenous GG. Accumulation of GG from the medium was essential for the restoration of photosynthesis and growth in mutant cells under high-salt conditions. In wild-type cells, the GG transporter probably serves to prevent GG leaking out of salt-stressed cells. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=17035