Demonstration that the BchH protein of Rhodobacter capsulatus activates S-adenosyl-L-methionine:magnesium protoporphyrin IX methyltransferase.

The bchH gene of Rhodobacter capsulatus has been cloned into an expression strain of Escherichia coli. Following induction of expression of the BchH protein, it was found that the E. coli strain also accumulated porphyrins with the fluorescence properties of protoporphyrin and zinc protoporphyrin. It was also found that the soluble BchH protein increased the activity of S-adenosyl-L-methionine:magnesium protoporphyrin IX methyltransferase, when mixed with membranes of an expression strain of E. coli into which the bchM gene (which encodes the methyltransferase) had been cloned, as well as membranes of a bchH mutant of R. capsulatus.