Abstract
The marine cyanobacterium, Synechococcus sp. Nägeli (strain RRIMP N1) changes its affinity for external inorganic carbon used in photosynthesis, depending on the concentration of CO2 provided during growth. The high affinity for CO2 + HCO3− of air-grown cells (K½ < 80 nanomoles [pH 8.2]) would seem to be the result of the presence of an inducible mechanism which concentrates inorganic carbon (and thus CO2) within the cells. Silicone-oil centrifugation experiments indicate that the inorganic carbon concentration inside suitably induced cells may be in excess of 1,000-fold greater than that in the surrounding medium, and that this accumulation is dependent upon light energy. The quantum requirements for O2 evolution appear to be some 2-fold greater for low CO2-grown cells, compared with high CO2-grown cells. This presumably is due to the diversion of greater amounts of light energy into inorganic carbon transport in these cells.
A number of experimental approaches to the question of whether CO2 or HCO3− is primarily utilized by the inorganic carbon transport system in these cells show that in fact both species are capable of acting as substrate. CO2, however, is more readily taken up when provided at an equivalent concentration to HCO3−. This discovery suggests that the mechanistic basis for the inorganic carbon concentrating system may not be a simple HCO3− pump as has been suggested. It is clear, however, that during steady-state photosynthesis in seawater equilibrated with air, HCO3− uptake into the cell is the primary source of internal inorganic carbon.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Andrews T. J., Abel K. M. Kinetics and subunit interactions of ribulose bisphosphate carboxylase-oxygenase from the cyanobacterium, Synechococcus sp. J Biol Chem. 1981 Aug 25;256(16):8445–8451. [PubMed] [Google Scholar]
- Badger M. R., Kaplan A., Berry J. A. Internal Inorganic Carbon Pool of Chlamydomonas reinhardtii: EVIDENCE FOR A CARBON DIOXIDE-CONCENTRATING MECHANISM. Plant Physiol. 1980 Sep;66(3):407–413. doi: 10.1104/pp.66.3.407. [DOI] [PMC free article] [PubMed] [Google Scholar]
- GUILLARD R. R., RYTHER J. H. Studies of marine planktonic diatoms. I. Cyclotella nana Hustedt, and Detonula confervacea (cleve) Gran. Can J Microbiol. 1962 Apr;8:229–239. doi: 10.1139/m62-029. [DOI] [PubMed] [Google Scholar]
- Miller A. G., Colman B. Active transport and accumulation of bicarbonate by a unicellular cyanobacterium. J Bacteriol. 1980 Sep;143(3):1253–1259. doi: 10.1128/jb.143.3.1253-1259.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miller A. G., Colman B. Evidence for HCO(3) Transport by the Blue-Green Alga (Cyanobacterium) Coccochloris peniocystis. Plant Physiol. 1980 Feb;65(2):397–402. doi: 10.1104/pp.65.2.397. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Radmer R. J., Kok B. Photoreduction of O(2) Primes and Replaces CO(2) Assimilation. Plant Physiol. 1976 Sep;58(3):336–340. doi: 10.1104/pp.58.3.336. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Radmer R., Ollinger O. Light-driven Uptake of Oxygen, Carbon Dioxide, and Bicarbonate by the Green Alga Scenedesmus. Plant Physiol. 1980 Apr;65(4):723–729. doi: 10.1104/pp.65.4.723. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WILKINSON G. N. Statistical estimations in enzyme kinetics. Biochem J. 1961 Aug;80:324–332. doi: 10.1042/bj0800324. [DOI] [PMC free article] [PubMed] [Google Scholar]