The hetC gene is a direct target of the NtcA transcriptional regulator in cyanobacterial heterocyst development.
The heterocyst is the site of nitrogen fixation in aerobically grown cultures of some filamentous cyanobacteria. Heterocyst development in Anabaena sp. strain PCC 7120 is dependent on the global nitrogen regulator NtcA and requires, among others, the products of the hetR and hetC genes. Expression of hetC, tested by RNA- DNA hybridization, was impaired in an ntcA mutant. A nitrogen-regulated, NtcA-dependent putative transcription start point was localized at nucleotide -571 with respect to the hetC translational start. Sequences upstream from this transcription start point exhibit the structure of the canonical cyanobacterial promoter activated by NtcA, and purified NtcA protein specifically bound to a DNA fragment containing this promoter. Activation of expression of hetC during heterocyst development appears thus to be directly operated by NtcA. NtcA-mediated activation of hetR expression was not impaired in a hetC mutant, indicating that HetC is not an NtcA-dependent element required for hetR induction.
Muro-Pastor
A M
AM
Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Centro de Investigaciones Científicas Isla de la Cartuja, E-41092 Seville, Spain.
Valladares
A
A
Flores
E
E
Herrero
A
A
D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D017033:Anabaena / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C109191:HetC protein, Anabaena; D010940:Plant Proteins; D014157:Transcription Factors; C067403:HetR protein, Bacteria; C075617:ntcA protein, Synechococcus; D009584:Nitrogen