title: Cloning and sequencing of the petBD operon from the cyanobacterium Synechococcus sp. PCC 7002.
abstract: The genes encoding the photosynthetic cytochrome b6 (petB) and subunit 4 (petD) have been cloned and sequenced from the unicellular, photoheterotrophic, transformable cyanobacterium Synechococcus sp. PCC 7002, formerly designated Agmenellum quadruplicatum. The gene arrangement was found to be similar to that reported in the cyanobacterium Nostoc PCC 7906. The DNA and derived protein sequences were compared to chloroplast and the other cyanobacterial sequences. By pulsed-field electrophoresis, the petBD operon and the petCA operon, encoding the Rieske iron-sulfur protein and cytochrome f, were found to be located on separate, unlinked, Not I-digested DNA fragments. The petBD operon was found on the third largest Not I fragment (NC-325) while the petCA operon was found on the second largest Not I fragment (NB-370). These results suggest the two operons are not in proximity. The 1.35 kb transcript was shown to be light-regulated. Transcripts from cells grown under constant illumination showed a decrease in petB transcript levels to undetectable levels within 2 h after the cells were placed in the dark. Upon reillumination, transcript levels rose to three-fold over that seen initially under constant illumination.
authors.affiliation: Department of Biochemical and Biophysical Sciences, University of Houston, TX 77204-5500.
authors.forename: S N
authors.initials: SN
authors.lastname: Brand
authors.forename: X
authors.initials: X
authors.lastname: Tan
authors.forename: W R
authors.initials: WR
authors.lastname: Widger
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000235:genetics*; D003573:Cytochrome b Group / Q000235:genetics*; D045346:Cytochrome b6f Complex; D003580:Cytochromes / Q000235:genetics*; D045348:Cytochromes f; D015964:Gene Expression Regulation, Bacterial / Q000528:radiation effects; D005798:Genes, Bacterial / Q000235:genetics*; D008969:Molecular Sequence Data; D010775:Photic Stimulation; D012333:RNA, Messenger / Q000032:analysis / Q000528:radiation effects; D017386:Sequence Homology, Amino Acid
chemical_list: D003573:Cytochrome b Group; D003580:Cytochromes; D012333:RNA, Messenger; D045346:Cytochrome b6f Complex; D045348:Cytochromes f