3ppn

Publication Abstract from PubMed

The compatible solute ATP-binding cassette (ABC) transporters are indispensable for acquiring a variety of compatible solutes under osmotic stress in Bacillus subtilis. The substrate-binding protein OpuCC of the ABC transporter OpuC can recognize a broad spectrum of compatible solutes, compared to its 70% sequence-identical paralog OpuBC that can solely bind choline. To explore the structural basis of this difference of substrate specificity, we determined crystal structures of OpuCC in the apo-form and in complex with carnitine, glycine betaine, choline and ectoine, respectively. OpuCC is composed of two alpha/beta/alpha globular sandwich domains linked by two hinge regions, with substrate-binding pocket located at the inter-domain cleft. Upon substrate-binding, the two domains shift towards each other to trap the substrate. Comparative structural analysis revealed a plastic pocket that fits various compatible solutes, which attributes the multiple-substrate binding property to OpuCC. This plasticity is a gain-of-function via a single-residue mutation of Thr94 in OpuCC versus Asp96 in OpuBC.

Structures of the substrate-binding protein provide insights into the multiple compatible solutes binding specificities of Bacillus subtilis ABC transporter OpuC.,Du Y, Shi WW, He YX, Yang YH, Zhou CZ, Chen Y Biochem J. 2011 Mar 3. PMID:21366542^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.