Heterologous Expression of BchP, a Rhodobacter capsulatus Polypeptide Necessary for the Reductive Maturation of Bacteriochlorophyll agg to Bacteriochlorophyll ap

Photosynthetic bacteria contain bacteriochlorophyll (BChl) which has two major portions, a magnesium tetrapyrrole and an esterifying alcohol. BChl plays a key role in photosynthesis which is necessary for converting radiant energy into energy that can be used in cellular processes. The esterifying alcohol portion affects the function of the BChl in photosynthesis, but its role is not well understood. Rhodobacter capsulatus typically produces BChl a esyrtified with phytol (BChl ap), but site directed mutational analysis has shown that a mutation is bchP results in the accumulation of a BChl a esterified with geranylgeraniol (BChl agg) indicating that the product of the bchP locus (the BchP polypeptide) is necessary for the reductive maturation of BChl agg to BChl ap. In order to determine if BchP is sufficient for this process, the gene has been amplified using polymerase chain reaction and restriction endonuclease sites have been created flanking the gene so that it can be cloned into a plasmid known as pT7-7. This construct was then transformed into a strain of E. coli (C600) which contains the pGPl-2 plasmid with the gene for T7 RNA polymerase which is under the control of the APL promoter. When the strain containing both plasmids is incubated at 42°C. T7 RNA polymerase is produced which can transcribe bchP producing BchP. Future work will include in vitro assays to determine if BchP is sufficient for the maturation of BChl agg to BChl ap