Subunit association as the stabilizing determinant for archaeal methionine adenosyltransferases.

ABSTRACT: Archaea contain a class of methionine adenosyltransferases (MATs) that exhibit substantially higher stability than their mesophilic counterparts. Their sequences are highly divergent, but preserve the essential active site motifs of the family. We have investigated the origin of this increased stability using chemical denaturation experiments on Methanococcus jannaschii MAT (Mj-MAT) and mutants containing single tryptophans in place of tyrosine residues. The results from fluorescence, circular dichroism, hydrodynamic, and enzyme activity measurements showed that the higher stability of Mj-MAT derives largely from a tighter association of its subunits in the dimer. Local fluorescence changes, interpreted using secondary structure predictions, further identify the least stable structural ele

SUBMITTER: Garrido F 

PROVIDER: S-EPMC2704562 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature