title: Differential transcriptional regulation of orthologous dps genes from two closely related heterocyst-forming cyanobacteria.
abstract: In cyanobacteria, DNA-binding proteins from starved cells (Dps) play an important role in the cellular response to oxidative and nutritional stresses. In this study, we have characterized the cell-type specificity and the promoter regions of two orthologous dps genes, Npun_R5799 in Nostoc punctiforme and alr3808 in Anabaena sp. PCC 7120. A transcriptional start site (TSS), identical in location to the previously identified proximal TSS of alr3808, was identified for Npun_R5799 under both combined nitrogen supplemented and N2-fixing growth conditions. However, only alr3808 was also transcribed from a second distal TSS. Sequence homologies suggest that the promoter region containing the distal TSS is not conserved upstream of orthologous genes among heterocyst-forming cyanobacteria. The analysis of promoter GFP-reporter strains showed a different role in governing cell-type specificity between the proximal and distal promoter of alr3808. We here confirmed the heterocyst specificity of the distal promoter of alr3808 and described a very early induction of its expression during proheterocyst differentiation. In contrast, the complete promoters of both genes were active in all cells. Even though Npun_R5799 and alr3808 are orthologs, the regulation of their respective expression differs, indicating distinctions in the function of these cyanobacterial Dps proteins depending on the strain and cell type.
authors: Microbial Chemistry, Department of Chemistry - Ångström Laboratory, Science for Life Laboratory, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden.
authors: Xin
authors: X
authors: Li
authors: Microbial Chemistry, Department of Chemistry - Ångström Laboratory, Science for Life Laboratory, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden.
authors: Gustaf
authors: G
authors: Sandh
authors: Microbial Chemistry, Department of Chemistry - Ångström Laboratory, Science for Life Laboratory, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden.
authors: Anja
authors: A
authors: Nenninger
authors: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, E-41092 Seville, Spain.
authors: Alicia M
authors: AM
authors: Muro-Pastor
authors: Microbial Chemistry, Department of Chemistry - Ångström Laboratory, Science for Life Laboratory, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden Karin.Stensjo@kemi.uu.se.
authors: Karin
authors: K
authors: Stensjö
mesh_terms: D017033:Anabaena / Q000235:genetics* / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D009584:Nitrogen / Q000378:metabolism; D046937:Nostoc / Q000235:genetics*; D011401:Promoter Regions, Genetic; D017385:Sequence Homology; D024363:Transcription Initiation Site
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D009584:Nitrogen
keywords: Anabaena; Cyanobacteria; DIF motif; Nostoc; ROS scavenging; ferritin-like protein; heterocyst differentiation