Structure-function of cyanobacterial outer-membrane protein, Slr1270: Homolog ofEscherichia colidrug export/colicin import protein, TolC

Rachna Agarwal, Stanislav Zakharov, S. Saif Hasan, Christopher M. Ryan, Julian P. Whitelegge, William A. Cramer
2014 FEBS Letters  
Compared to thylakoid and inner membrane proteins in cyanobacteria, no structure-function information is available presently for integral outer-membrane proteins (OMPs). The Slr1270 protein from the cyanobacterium Synechocystis 6803, over-expressed in Escherichia coli, was refolded, and characterized for molecular size, secondary structure, and ion-channel function. Refolded Slr1270 displays a single band in native-electrophoresis, has an a-helical content of 50-60%, as in E. coli TolC with
more » ... h it has significant secondary-structure similarity, and an ion-channel function with a single-channel conductance of 80-200 pS, and a monovalent ion (K + :Cl À ) selectivity of 4.7:1. The pH-dependence of channel conductance implies a role for carboxylate residues in channel gating, analogous to that in TolC. Structured summary of protein interactions: Slr1270 and Slr1270 bind by molecular sieving (1, 2) TolC and TolC bind by molecular sieving (View interaction)
doi:10.1016/j.febslet.2014.08.028 pmid:25218435 pmcid:PMC4288923 fatcat:jppjvepcrvb6vahnljjvbvzpz4