Comparative Analysis of the Dynamics of the Binding Protein-Dependent Histidine ABC Import System and the ECF-Type Biotin Transporter

Canonical ABC transport systems mediating the uptake of solutes in prokaryotes are composed of an extracytoplasmic solute binding protein (receptor), two pore-forming subunits and an ATPase dimer. Our current knowledge on the transport mechanism is largely based on structural and functional analysis of the maltose transporter of E. coli/Salmonella. Due to some unique features of this system it is questionable whether the derived transport model holds for other ABC importers. Thus, we will study conformational changes of the similarly well-characterized histidine transporter, HisJ/LAO-QMP2, of S. typhimurium by means of mutational analysis, site-specific chemical cross-linking, and limited proteolysis. We aim to elucidate transporter-receptor interactions at different steps of the transport cycle and to identify motional changes of HisQM associated with opening/closing of the HisP dimer upon ATP binding/hydrolysis. These studies will guide similar experiments with the BioMNY transporter, a member of the newly discovered subfamily of ECF-transporters. The latter lack a receptor and thus resemble binding protein-independent mutants of the maltose and histidine transporter. We will investigate whether these mutants, like the substrate-specific membrane protein of ECF transporters, can function as a secondary transport system in the absence of the ATPase subunits.

Principal Investigators
Schneider, Erwin Prof. Dr. rer. nat. (Details) (Physiology of Microorganisms)

Duration of Project
Start date: 10/2009
End date: 02/2013

Last updated on 2020-25-11 at 15:03