title: A TolC-like protein is required for heterocyst development in Anabaena sp. strain PCC 7120.
abstract: The filamentous cyanobacterium Anabaena sp. strain PCC 7120 forms heterocysts in a semiregular pattern when it is grown on N2 as the sole nitrogen source. The transition from vegetative cells to heterocysts requires marked metabolic and morphological changes. We show that a trimeric pore-forming outer membrane beta-barrel protein belonging to the TolC family, Alr2887, is up-regulated in developing heterocysts and is essential for diazotrophic growth. Mutants defective in Alr2887 did not form the specific glycolipid layer of the heterocyst cell wall, which is necessary to protect nitrogenase from external oxygen. Comparison of the glycolipid contents of wild-type and mutant cells indicated that the protein is not involved in the synthesis of glycolipids but might instead serve as an exporter for the glycolipid moieties or enzymes involved in glycolipid attachment. We propose that Alr2887, together with an ABC transporter like DevBCA, is part of a protein export system essential for assembly of the heterocyst glycolipid layer. We designate the alr2887 gene hgdD (heterocyst glycolipid deposition protein).
authors.affiliation: LMU, Department of Biology I, VW-Research Group, Menzinger Str. 67, 80638 München, Germany.
authors.forename: Suncana
authors.initials: S
authors.lastname: Moslavac
authors.forename: Kerstin
authors.initials: K
authors.lastname: Nicolaisen
authors.forename: Oliver
authors.initials: O
authors.lastname: Mirus
authors.forename: Fadi
authors.initials: F
authors.lastname: Al Dehni
authors.forename: Rafael
authors.initials: R
authors.lastname: Pernil
authors.forename: Enrique
authors.initials: E
authors.lastname: Flores
authors.forename: Iris
authors.initials: I
authors.lastname: Maldener
authors.forename: Enrico
authors.initials: E
authors.lastname: Schleiff
mesh_terms: D017033:Anabaena / Q000145:classification / Q000235:genetics / Q000502:physiology*; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D005819:Genetic Markers; D005838:Genotype; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D010957:Plasmids; D011487:Protein Conformation; D012329:RNA, Bacterial / Q000235:genetics / Q000302:isolation & purification
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D017931:DNA Primers; D005819:Genetic Markers; D026901:Membrane Transport Proteins; D012329:RNA, Bacterial