Ligand binding and crystal structures of the substrate-binding domain of the ABC transporter OpuA.

ABSTRACT:

Background

The ABC transporter OpuA from Lactococcus lactis transports glycine betaine upon activation by threshold values of ionic strength. In this study, the ligand binding characteristics of purified OpuA in a detergent-solubilized state and of its substrate-binding domain produced as soluble protein (OpuAC) was characterized.

Principal findings

The binding of glycine betaine to purified OpuA and OpuAC (K(D) = 4-6 microM) did not show any salt dependence or cooperative effects, in contrast to the transport activity. OpuAC is highly specific for glycine betaine and the related proline betaine. Other compatible solutes like proline and carnitine bound with affinities that were 3 to 4 orders of magnitude lower. The low affinity substrates were not noticeably transported by

SUBMITTER: Wolters JC 

PROVIDER: S-EPMC2861598 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature