Role of arginine-304 in the diphosphate-triggered active site closure mechanism of trichodiene synthase.

ABSTRACT: The X-ray crystal structures of R304K trichodiene synthase and its complexes with inorganic pyrophosphate (PP(i)) and aza analogues of the bisabolyl carbocation intermediate are reported. The R304K substitution does not cause large changes in the overall structure in comparison with the wild-type enzyme. The complexes with (R)- and (S)-azabisabolenes and PP(i) bind three Mg2+ ions, and each undergoes a diphosphate-triggered conformational change that caps the active site cavity. This conformational change is only slightly attenuated compared to that of the wild-type enzyme complexed with Mg2+(3)-PP(i), in which R304 donates hydrogen bonds to PP(i) and D101. In R304K trichodiene synthase, K304 does not engage in any hydrogen bond interactions in the unliganded state and it donates a hydroge

SUBMITTER: Vedula LS 

PROVIDER: S-EPMC1386727 | biostudies-literature | 2005 Sep

REPOSITORIES: biostudies-literature