title: Propensity for C-terminal domain swapping correlates with increased regional flexibility in the C-terminus of RNase A.
abstract: Domain swapping is a type of oligomerization in which monomeric proteins exchange a structural element, resulting in oligomers whose subunits recapitulate the native, monomeric fold. It has been implicated as a potential mechanism for protein aggregation, which provides a strong impetus to understand the structural determinants and folding mechanisms that trigger domain swapping. Bovine pancreatic ribonuclease A (RNase A) is a well-studied protein known to domain swap under extreme conditions, such as lyophilization from acetic acid. The major domain-swapped dimer form of RNase A exchanges a β-strand at its C-terminus to form a C-terminal domain-swapped dimer. To study the mechanism by which C-terminal swapping occurs, we used a variant of RNase A containing a P114G mutation that readily domain swaps under physiological conditions. Using NMR and hydrogen-deuterium exchange, we find that the P114G variant has decreased protection from hydrogen exchange compared to the wild-type protein near the C-terminal hinge region. Our results suggest that domain swapping occurs via a local high-energy fluctuation at the C-terminus.
authors.affiliation: Biophysics Graduate Group, University of California, Berkeley, California 94720, USA.
authors.forename: Katherine H
authors.initials: KH
authors.lastname: Miller
authors.forename: Susan
authors.initials: S
authors.lastname: Marqusee
mesh_terms: D000818:Animals; D002417:Cattle; D008958:Models, Molecular; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010179:Pancreas / Q000201:enzymology*; D011487:Protein Conformation; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D012259:Ribonuclease, Pancreatic / Q000737:chemistry* / Q000235:genetics
chemical_list: D012259:Ribonuclease, Pancreatic