SYNECHOCYSTIS SP PCC6803 FUSB GENE, LOCATED OUTSIDE OF THE STR OPERON, ENCODES A POLYPEPTIDE RELATED TO PROTEIN-SYNTHESIS FACTOR EF-G

Synechocystis sp. PCC6803, a cyanobacterium, possesses an unusual gene (fusB) which encodes a protein with strong homology to protein synthe sis elongation factor G (EF-G), although it is not linked to the class ical str operon. The fusB gene is redundant, since a Synechocystis gen e similar to str operon-encoded fusA genes of other bacteria is also p resent (based on PCR and hybridization results). There is no evidence for the presence of a fusB homologue in other bacteria. The Synechocys tis fusB gene encodes unusual amino acids at some positions that are h ighly conserved in fusA genes of other prokaryotes.