The sigA gene encoding the major sigma factor of RNA polymerase from the marine cyanobacterium Synechococcus sp. strain PCC 7002: cloning and characterization.
The gene encoding the principal sigma factor from Synechococcus sp. strain PCC 7002 was isolated and characterized. The Synechococcus sp. strain PCC 7002 sigA gene encodes a protein of 375 amino acids (43 center dot 7 kDa) that is required for viability under normal growth conditions. The SigA protein was overproduced in Escherichia coli and the purified protein was used to raise polyclonal antiserum in rabbits. This antiserum was used in immunoblot analyses of partially purified RNA polymerase from Synechococcus sp. strain PR6000. The probable in vivo translational start site was identified by a comparison of amino acid sequencing results obtained with SigA proteins overproduced in E. coli with immunoblot analyses of SigA protein in crude preparations of RNA polymerase from the cyanobacterium. The sigA gene is encoded on a transcript of 1700 bases that initiates 496 nucleotides upstream from the probable in vivo translational start site. The abundance of sigA transcripts decreases rapidly after the removal of combined nitrogen from the growth medium.
Osborn
A M
AM
Department of Genetics and Microbiology, Donnan Laboratories, University of Liverpool, PO Box 147, Liverpool L69 3BX, UK.
Bruce
K D
KD
Department of Genetics and Microbiology, Donnan Laboratories, University of Liverpool, PO Box 147, Liverpool L69 3BX, UK.
Ritchie
D A
DA
Department of Genetics and Microbiology, Donnan Laboratories, University of Liverpool, PO Box 147, Liverpool L69 3BX, UK.
Strike
P
P
Department of Genetics and Microbiology, Donnan Laboratories, University of Liverpool, PO Box 147, Liverpool L69 3BX, UK.
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000235:genetics* / Q000276:immunology; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D012321:DNA-Directed RNA Polymerases / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D015151:Immunoblotting; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D012329:RNA, Bacterial / Q000235:genetics; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D012808:Sigma Factor / Q000032:analysis / Q000235:genetics* / Q000276:immunology
D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012808:Sigma Factor; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases