title: A two-component signal transduction pathway regulates manganese homeostasis in Synechocystis 6803, a photosynthetic organism.
abstract: Elemental manganese is essential for the production of molecular oxygen by cyanobacteria, plants, and algae. In the cyanobacterium Synechocystis sp. PCC 6803, transcription of the mntCAB operon, encoding a high affinity Mn transporter, occurs under Mn starvation (nm Mn) conditions but not in Mn-sufficient (microm Mn) growth medium. Using a strain in which the promoter of this operon directs the transcription of the luxAB reporter genes, we determined that inactivation of the slr0640 gene, which encodes a histidine kinase sensor protein component of a two-component signal transduction system, resulted in constitutive high levels of lux luminescence. Systematic targeted inactivation mutagenesis also identified slr1837 as the gene encoding the corresponding response regulator protein. We have named these two genes manS (manganese-sensor) and manR (manganese-regulator), respectively. A polyhistidine-tagged form of the ManS protein was localized in the Synechocystis 6803 cell membrane. Directed replacement of the conserved catalytic His-205 residue of this protein by Leu abolished its activity, although the mutated protein was present in cyanobacterial membrane. This mutant also showed suboptimal rates of Mn uptake under either Mn-starved or Mn-sufficient growth condition. These data suggest that the ManS/ManR two-component system plays a central role in the homeostasis of manganese in Synechocystis 6803 cells.
authors.affiliation: Bioscience Center, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
authors.forename: Teruo
authors.initials: T
authors.lastname: Ogawa
authors.forename: Ding Hui
authors.initials: DH
authors.lastname: Bao
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Katoh
authors.forename: Mari
authors.initials: M
authors.lastname: Shibata
authors.forename: Himadri B
authors.initials: HB
authors.lastname: Pakrasi
authors.forename: Maitrayee
authors.initials: M
authors.lastname: Bhattacharyya-Pakrasi
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D001426:Bacterial Proteins; D001692:Biological Transport; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics; D020134:Catalytic Domain; D000458:Cyanobacteria / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D017930:Genes, Reporter / Q000235:genetics; D016153:Genes, Suppressor; D006639:Histidine / Q000737:chemistry; D000071677:Histidine Kinase; D007700:Kinetics; D007930:Leucine / Q000737:chemistry; D008345:Manganese / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics; D033902:Periplasmic Binding Proteins; D010788:Photosynthesis; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; C119581:MntB protein, Synechocystis; C432956:MntC protein, Neisseria gonorrhoeae; D009687:Nuclear Proteins; D033902:Periplasmic Binding Proteins; D012333:RNA, Messenger; D008345:Manganese; D006639:Histidine; D011494:Protein Kinases; D000071677:Histidine Kinase; D007930:Leucine