HETEROLOGOUS EXPRESSION OF THE BCHM GENE-PRODUCT FROM RHODOBACTER-CAPSULATUS AND DEMONSTRATION THAT IT ENCODES S-ADENOSYL-L-METHIONINE-MG-PROTOPORPHYRIN-IX METHYLTRANSFERASE
Dw. Bollivar et al., HETEROLOGOUS EXPRESSION OF THE BCHM GENE-PRODUCT FROM RHODOBACTER-CAPSULATUS AND DEMONSTRATION THAT IT ENCODES S-ADENOSYL-L-METHIONINE-MG-PROTOPORPHYRIN-IX METHYLTRANSFERASE, Journal of bacteriology, 176(17), 1994, pp. 5290-5296
The bacteriochlorophyll biosynthesis gene, bchM, from Rhodobacter caps
ulatus was previously believed to code for a polypeptide involved in f
ormation of the cyclopentone ring of protochlorophyllide from Mg-proto
porphyrin IX monomethyl ester. In this study, R. capsulatus bchM was e
xpressed in Escherichia coli and the gene product was subsequently dem
onstrated by enzymatic analysis to catalyze methylation of Mg-protopor
phyrin IX to form Mg-protoporphyrin IX monomethyl ester. Activity requ
ired the substrates Mg-protoporphyrin IX and S-adenosyl-L-methionine.
C-14-labeled product was formed in incubations containing C-13-methyl-
labeled S-adenosyl-L-methionine. On the basis of these and previous re
sults, we also conclude that the bchH gene, which was previously repor
ted to code for Mg-protoporphyrin IX methyltransferase, is most likely
involved in the Mg chelation step.