Abstract
The main parts of chlorosomes in green sulfur bacteria are self-aggregates of BChls-c/d/e without support of proteins. We have reported that novel compounds prepared by organic synthetic methods self-aggregated under various conditions in vitro to form similar oligomers with natural chlorosomes. Such organic synthetic procedures are limited because introduction of a methyl group to a specific site in a tetrapyrrole ring is difficult to be carried out. As chlorosomal BChls have many methyl groups, efficient methylation is necessary to prepare various model compounds containing methyl groups specifically. Recently, BChl c biosynthetic pathway in Chlorobium tepidum has been postulated. We focused on the methyltransferases in the pathway, and attempted to utilize these enzymes for introducing methyl groups in vitro. In this study, we cloned BChl c 20-methyltranferase gene, bchU, and overexpressed it in E. coli. We are now going to measure BchU enzymatic activity with many substrates.
