Nucleotide and Deduced Polypeptide Sequences of the Photosynthetic
Reaction-center, B870 antenna, and Flanking Polypeptides from R. capsulata
Youvan D.C., Bylina E.J., Alberti M., Begusch H., Hearst J.E.
The complete nucleotide sequence (8867 bp) and the deduced polypeptide sequence are given
for 11 proteins from the photosynthetic gene cluster of R. capsulata (46 kb),
including the photosynthetic reaction-center L, M, and H subunits and the B870 alpha and
B870 beta polypeptides (light-harvesting I). These polypeptides bind bacteriochlorophyll,
bacteriopheophytin, carotenoids, and quinones that are involved in the primary light
reactions of photosynthesis. Hydropathy plots indicate that the L and M subunits are
transmembrane proteins that may cross the membrane five times, while the H subunit has
only one hydrophobic section near the amino terminus, which may be transmembrane. The L
and M subunits are homologous over their entire length and have a high degree of homology
with the QB protein from photosystem II of higher plants. An additional six genes were
identified that may have some unknown role in bioenergetics since only mutations that
affect the differentiation of the photosynthetic apparatus are known to map to this gene
cluster.