Osmoregulated ABC-transport system of Lactococcus lactis senses water stress via changes in the physical state of the membrane.

ABSTRACT: An osmoregulated ABC transporter (OpuA) with novel structural features has been identified that responds to water stress. This glycine betaine transport system consists of an ATP-binding/hydrolyzing subunit (OpuAA) and a protein (OpuABC) that contains both the translocator and the substrate-binding domain. The components of OpuA have been overexpressed, purified, and functionally incorporated into liposomes with an ATP-regenerating system in the vesicle lumen. A transmembrane osmotic gradient (outside hyperosmotic relative to the inside) of both ionic and nonionic compounds was able to osmotically activate OpuA in the proteoliposomal system. Hypoosmotic medium conditions inhibited the basal activity of the system. The data show that OpuAA and OpuABC are sufficient for osmoregulated transpo

SUBMITTER: van der Heide T 

PROVIDER: S-EPMC16506 | biostudies-literature | 2000 Jun

REPOSITORIES: biostudies-literature