PARENT SESSION
Posters P5C Biosynthesis and assembly: Pigments. Abstracts (643-659)

Expression of genes involved in bacteriochlorophyll synthesis in cyanobacteria Synechocystis sp. PCC6803. Masahiro Atsuta^*,1, Yosuke Hashimoto², Tomoyuki Seki², Takanori Gotoh³, Yuka Itoh³, Masami Kobayashi³, Kazuhito Inoue², ¹ Biological Sciences Department, Tokyo, Japan² Biological Sciences Department, Hiratsuka, kanagawa, Japan³ Institute of Materials Science, Tsukuba, Ibaraki, Japan

ABSTRACT- Chl a is synthesized from chlorophyllide (Chlide) a by esterification of long alcohol chain to its side-chain of ring D, while BChl a is synthesized from bacteriochlorophyllide a. To convert chlide a to BChl a, there must be three reactions: (i) the reduction of the double bond of ring B which is catalyzed by a three-subunit enzyme complex, chlorophyllide a reductase, encoded by the three genes, bchX, bchY and bchZ, (ii) the conversion of the C3 vinyl group to an acetyl group in which the products of the bchC and bchF seems to be involved, and (iii) the esterification occurring between bacteriochlorophyllide a and long alcohol chain which are catalyzed by bacteriochlorophyll synthase encoded on bchG. The biosynthetic pathway of BChl a was studied previously with various mutants of the purple bacterium, Rhodobacter spheroides, unable to synthesize BChl a, though the reaction from chlorophyllide a to BChl a is not proven biochemically. In this study, we constructed expression vector of bchF and bchG from green sulfur bacterium Chlorobium tepidum and purple sulfur bacteria Rhodobacter capsulatus and introduced them into cyanobacteria Synechocystis sp. PCC6803.

KEY WORDS: chlorophyll a, bacteriochlorophyll a, Chlorobium tepidum, Synechocystis sp. PCC6803