Poster abstracts

Poster number 54 submitted by Seth Hennon

Proximity relationships and tertiary contacts of the YidC transmembrane segments

Seth Hennon (Department of Chemistry, The Ohio State University), Lu Zhu (Department of Chemistry, The Ohio State University)

Abstract:
YidC is an evolutionarily conserved insertase that is involved in the integration and assembly of Escherichia coli inner membrane proteins. YidC is essential for bacterial growth and homologues of YidC are found in the eukaryotic mitochondria (Oxa1) and plant chloroplasts (Alb3). Interestingly, all three homologues have a conserved insertion mechanism and are functionally interchangeable. In order to carry out its insertase role, YidC can work in concert with the SecYEG translocon to insert proteins into the membrane or can mediate the insertion by itself. X-ray crystallography has been used to determine the structure of the YidC major periplasmic domain between transmembrane helices one and two but a structure for the full-length protein has not been solved.

In order to gain structural insight, the YidC insertase of E. coli containing various double cysteine mutations was expressed and cross-linking was studied. Proximity of the cysteine pairs in regions at the membrane-aqueous boundary and within the membrane was probed using membrane permeable thiol specific cross-linking reagents of different lengths and flexibilities. Contacts were observed between TM2 and TMs 3,4,5 and 6. The data are being used to determine helical packing, interhelical contacts and tilt, which will lead to a structural model of the YidC transmembrane region.

Keywords: Membrane Protein, YidC