title: Characterization of Synechocystis sp. PCC 6803 in iron-supplied and iron-deficient media.
abstract: The photosynthetic apparatus is rich in iron-containing cofactors and iron deficiency causes severe impairment of photosynthesis in plants, algae, and cyanobacteria. Synechocystis sp. PCC 6803 serves as a model system to investigate the complex assembly and integration of the multi-subunit protein complexes of oxygenic photosynthetic electron transport; particularly when coupled to developmental cues due to nutrient limitation or requirements. We study Fe(3+)-deficient and Fe(3+)-supplemented cultures of Synechocystis sp. PCC 6803. The autotrophic growth rate of Fe(3+)-deficient cultures is slower than Fe(3+)-supplemented cultures. Whole cell spectral analysis reveals differences in both the quantity and the peak absorbance of chlorophyll. Fe3+ deficiency decreases rates of photosynthetic electron transport and the mRNA and corresponding protein levels as observed using specific probes. mRNA levels of psaB increased 20-fold during recovery from Fe3+ deficiency, as compared to the control. psaD transcript levels increased to 160% during recovery as compared to the control. PsaA/B heterodimer formation and turnover is dependent on Fe3+ and the complete assembly on the reducing side of photosystem I (PS I) is PsaD-dependent. Recovery from Fe3+ deficiency suggests that regulation occurs at both the mRNA and protein level.
authors.affiliation: Division of Biology, Kansas State University, Manhattan 66506-4901.
authors.forename: W R
authors.initials: WR
authors.lastname: Odom
authors.forename: R
authors.initials: R
authors.lastname: Hodges
authors.forename: P R
authors.initials: PR
authors.lastname: Chitnis
authors.forename: J A
authors.initials: JA
authors.lastname: Guikema
mesh_terms: D002736:Chloroplasts / Q000378:metabolism; D000458:Cyanobacteria / Q000737:chemistry / Q000378:metabolism*; D004579:Electron Transport / Q000187:drug effects; D005786:Gene Expression Regulation; D007501:Iron / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes; D008353:Mannitol / Q000494:pharmacology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D045331:Photosystem I Protein Complex; D012333:RNA, Messenger / Q000235:genetics; D013057:Spectrum Analysis; D014882:Water-Electrolyte Balance
chemical_list: D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D012333:RNA, Messenger; D008353:Mannitol; D007501:Iron