Structure of the cytosolic domain of TOM5, a mitochondrial import protein

Abstract

TOM5 is a small outer mitochondrial membrane protein in Saccharomyces cerevisiae and is part of a multi-protein translocator complex, which mediates protein import into mitochondria. Presently, nothing is known about the conformational preferences of TOM5 or other mitochondrial import proteins. In this report, circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy are used to determine the conformational preferences of the cytosolic domain of TOM5. The CD spectra show evidence of a helical structure that is invariant with pH. NOESY data revealed that TOM5 forms a stable helical core between E11 and R15 with a less structurally rigid helix extending to the C-terminus.