Active transport of glucosylglycerol is involved in salt adaptation of the cyanobacterium Synechocystis sp. strain PCC 6803

• Published in: Microbiology (Society for General Microbiology) Vol. 142; no. 7; pp. 1725 - 1732
• Main Authors: Mikkat, Stefan, Hagemann, Martin, Schoor, Arne
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.07.1996; Society for General Microbiology
• Subjects: Adaptation, Physiological; Antimetabolites - pharmacology; Bacteriology; Biological and medical sciences; Biological Transport, Active - drug effects; Cyanobacteria - drug effects; Cyanobacteria - genetics; Cyanobacteria - metabolism; Fundamental and applied biological sciences. Psychology; Genetic Complementation Test; Glucosides - pharmacokinetics; Kinetics; Microbiology; Mutation; Permeability, membrane transport, intracellular transport; Sodium Chloride - pharmacology; Halotolerance; Membrane transport; Cyanobacteria; Osmoregulation; Bacteria; Synechocystis; Carrier protein; Adaptation; Salinity
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/13500872-142-7-1725

Department of Biology, University of Rostock, 18051 Rostock, Germany 2 Author for correspondence: Stefan Mikkat. Tel: +49 381 494 2071. Fax: +49 381 494 2079. ABSTRACT An active-transport system for the osmoprotective compound glucosylglycerol (GG) was found in the cyanobacterium Synechocystis sp. strain PCC 6803. Uptake assays with 14 C-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. Keywords: osmoprotective compound, glucosylglycerol transport, salt adaptation, cyanobacterium, Synechocystis sp.