Long-range side-chain-main-chain interactions play crucial roles in stabilizing the (betaalpha)8 barrel motif of the alpha subunit of tryptophan synthase.

ABSTRACT: The role of hither-to-fore unrecognized long-range hydrogen bonds between main-chain amide hydrogens and polar side chains on the stability of a well-studied (betaalpha)8, TIM barrel protein, the alpha subunit of tryptophan synthase (alphaTS), was probed by mutational analysis. The F19-D46 and I97-D124 hydrogen bonds link the N terminus of a beta-strand with the C terminus of the succeeding antiparallel alpha-helix, and the A103-D130 hydrogen bond links the N terminus of an alpha-helix with the C terminus of the succeeding antiparallel beta-strand, forming clamps for the respective betaalpha or alphabeta hairpins. The individual replacement of these aspartic acid side chains with alanine leads to what appear to be closely related partially folded structures with significantly reduced far-U

SUBMITTER: Yang X 

PROVIDER: S-EPMC2206699 | biostudies-literature | 2007 Jul

REPOSITORIES: biostudies-literature