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Propensity for C‐terminal domain swapping correlates with increased regional flexibility in the C‐terminus of RNase A
Author(s) -
Miller Katherine H.,
Marqusee Susan
Publication year - 2011
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.708
Subject(s) - dimer , hydrogen–deuterium exchange , rnase p , chemistry , c terminus , protein folding , rnase h , biophysics , biochemistry , stereochemistry , amino acid , rna , biology , hydrogen , gene , organic chemistry
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.