An alternative allosteric pathway in thermophilic methylglyoxal synthase.

Methylglyoxal synthase (MGS) is a homohexameric enzyme responsible for converting dihydroxyacetone phosphate (DHAP) to methylglyoxal and phosphate in the methylglyoxal bypass of glycolysis. Phosphate acts as an allosteric inhibitor and strong regulator for this enzyme. Previous studies on MGS from Thermus sp. GH5 (TMGS) had indicated a pathway for transmitting the signal through Pro82, Arg97 and Val101 to the active site. The necessity of these residues for heterotropic negative cooperativity between subunits of TMGS were also proposed. In this study, it has been shown that a path via a salt bridge between Arg80 and Asp100 in the narrow dimer interface provides an alternative pathway for transmission of the allosteric inhibitory signal through subunit interfaces.