title: Cellular and functional specificity among ferritin-like proteins in the multicellular cyanobacterium Nostoc punctiforme.
abstract: Ferritin-like proteins constitute a remarkably heterogeneous protein family, including ferritins, bacterioferritins and Dps proteins. The genome of the filamentous heterocyst-forming cyanobacterium Nostoc punctiforme encodes five ferritin-like proteins. In the present paper, we report a multidimensional characterization of these proteins. Our phylogenetic and bioinformatics analyses suggest both structural and physiological differences among the ferritin-like proteins. The expression of these five genes responded differently to hydrogen peroxide treatment, with a significantly higher rise in transcript level for Npun_F3730 as compared with the other four genes. A specific role for Npun_F3730 in the cells tolerance against hydrogen peroxide was also supported by the inactivation of Npun_F3730, Npun_R5701 and Npun_R6212; among these, only the ΔNpun_F3730 strain showed an increased sensitivity to hydrogen peroxide compared with wild type. Analysis of promoter-GFP reporter fusions of the ferritin-like genes indicated that Npun_F3730 and Npun_R5701 were expressed in all cell types of a diazotrophic culture, while Npun_F6212 was expressed specifically in heterocysts. Our study provides the first comprehensive analysis combining functional differentiation and cellular specificity within this important group of proteins in a multicellular cyanobacterium.
authors.affiliation: Department of Chemistry - Ångström Laboratory, Uppsala University, SE-751 20, Uppsala, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Ekman
authors.forename: Gustaf
authors.initials: G
authors.lastname: Sandh
authors.forename: Anja
authors.initials: A
authors.lastname: Nenninger
authors.forename: Paulo
authors.initials: P
authors.lastname: Oliveira
authors.forename: Karin
authors.initials: K
authors.lastname: Stensjö
mesh_terms: D000595:Amino Acid Sequence; D019295:Computational Biology; D005293:Ferritins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007501:Iron / Q000378:metabolism; D046937:Nostoc / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D010802:Phylogeny; D016415:Sequence Alignment
chemical_list: D016877:Oxidants; D049452:Green Fluorescent Proteins; D005293:Ferritins; D006861:Hydrogen Peroxide; D007501:Iron