In Vitro Assays of BciC Showing C132-Demethoxycarbonylase Activity Requisite for Biosynthesis of Chlorosomal Chlorophyll Pigments

In this study, we characterized the BciC derived from the green sulfur bacterium Chlorobaculum tepidum, and examined the in vitro enzymatic activities of its recombinant protein. The BciC-catalyzing reactions of various substrates showed that the enzyme recognized chlorophyllide (Chlide) a and 3,8-divinyl(DV)-Chlide a as chlorin substrates to give 3-vinyl-bacteriochlorophyllide (3V-BChlide) d and DV-BChlide d, respectively. Since the BciC afforded a higher activity with Chlide a than that with DV-Chlide a and no activity with (DV-)protoChlides a (porphyrin substrates) and 3V-BChlide a (a bacteriochlorin substrate), this enzyme was effective for diverting the chlorosomal pigment biosynthetic pathway at the stage of Chlide a away from syntheses of other pigments such as BChl a and Chl a. The addition of methanol to the reaction mixture did not prevent the BciC activity, and we identified this enzyme as Chlide a demethoxycarbonylase, not methylesterase.

Source: Plant and Cell Physiology - May 12, 2016 Category: Cytology Authors: Teramura, M., Harada, J., Mizoguchi, T., Yamamoto, K., Tamiaki, H. Tags: Regular Papers Source Type: research