title: The Rubisco activase (rca) gene is located downstream from rbcS in Anabaena sp. strain CA and is detected in other Anabaena/Nostoc strains.
abstract: A gene encoding ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase (rca) was found downstream from the rbcLrbcS operon in the heterocystous cyanobacterium Anabaena sp. strain CA. Two unknown open reading frames were shown to be located between rbcS and rca in strain CA and all the genes, rbcLrbcS, ORF1, ORF2, and rca were in the same transcriptional orientation. The deduced amino acid sequence of the Anabaena Rubisco activase showed both similarities and differences to the plant enzyme with considerable differences at the carboxy and amino termini. Proposed ATP-binding sites were conserved in the cyanobacterial protein. Recombinant cyanobacterial Rubisco activase, however, reacted with antisera to spinach Rubisco activase. Hybridization studies, using the Anabaena sp. strain CA rca gene as a heterologous probe, detected homologous sequences in heterocystous Anabaena/Nostoc strains but not in unicellular or nonheterocystous filamentous cyanobacteria, suggestive of a close evolutionary relationship of chloroplasts and heterocystous cyanobacteria.
authors: Department of Microbiology, Ohio State University, Columbus 43210-1192.
authors: L A
authors: LA
authors: Li
authors: J L
authors: JL
authors: Gibson
authors: F R
authors: FR
authors: Tabita
mesh_terms: D000595:Amino Acid Sequence; D017033:Anabaena / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000235:genetics; D015342:DNA Probes; D004926:Escherichia coli; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D016366:Open Reading Frames; D010940:Plant Proteins; D011994:Recombinant Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D012273:Ribulose-Bisphosphate Carboxylase / Q000096:biosynthesis / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D015342:DNA Probes; D010940:Plant Proteins; D011994:Recombinant Proteins; C054765:rca protein, plant; D012273:Ribulose-Bisphosphate Carboxylase