Poster Presentation The 43rd Lorne Conference on Protein Structure and Function 2018

Characterisation of a multimeric form of the periplasmic chaperone, SurA (#160)

Rebecca S Bamert 1 , Iain D Hay 1 , Trevor Lithgow 1
  1. Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia

SurA functions as a periplasmic chaperone in E.coli, helping to transport nascent β-barrel proteins from the SEC translocase in the inner membrane, across the periplasm, to the outer membrane. Previous structural information suggests that SurA functions as a monomer or possibly dimer, however another periplasmic holdase chaperone, Skp, has been shown to assemble into a multimeric protective cage around similar unfolded substrates as it transports them to the OM from the SEC translocase. Following from the observation that overexpressed SurA forms a higher MW species, we are characterising this multimeric form of the protein. Size exclusion chromatography and SEC-MALS of purified, overexpressed SurA show a distinct 450kDa species (~10-mer) that dissociates over time to a monomer. Preliminary electron-microscopy analysis has shown a homogenous population of asymmetric yet regular particles that await further cryo-EM characterisation.