Association of Carbonic Anhydrase Activity with Carboxysomes Isolated from the Cyanobacterium Synechococcus PCC7942
- 1 October 1992
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 100 (2), 784-793
- https://doi.org/10.1104/pp.100.2.784
Abstract
The development of a simple method for the isolation of purified carboxysomes from the cyanobacterium Synechococcus PCC7942 has made it possible to identify a specific and inducible, intracellular carbonic anhydrase (CA) activity that is strongly associated with carboxysomes. This was shown, in part, through enzyme recovery experiments that indicated that a clear majority of a CA activity that is sensitive to the CA inhibitor ethoxyzolamide (I50 = 4 μm) copurifies with a majority of the cell's ribulose-1,5-bisphosphate carboxylase/oxygenase activity in a highly purified pelletable fraction. Electron microscopy of this pelletable fraction revealed the presence of carboxysomes that were physically intact. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of carboxysome proteins showed that the large and small subunits of ribulose-1,5-bisphosphate carbosylase/oxygenase were clearly prominent and that several other minor proteins could be distinguished. The specific location of this carboxysomal CA activity is further reinforced by the finding that a previously isolated high CO2-requiring mutant, Type II/No. 68 (G.D. Price, M.R. Badger [1989] Plant Physiol 91: 514-525), displayed a 30-fold reduction in carboxysome-associated CA activity when tested under optimal conditions. Carboxysomal CA has the unusual property of being inactivated by dithiothreitol. The enzyme also requires 20 mm Mg2+ (as MgSO4) for near maximum activity; other divalent cations, such as Ca2+ and Mn2+, also stimulate carboxysomal CA activity, but to a lesser extent than Mg2+. Results are discussed in relation to the role of carboxysomes in the CO2-concentrating mechanism in cyanobacteria and the role that carboxysomal CA activity appears to play in this process.Keywords
This publication has 16 references indexed in Scilit:
- Isolation of a Putative Carboxysomal Carbonic Anhydrase Gene from the Cyanobacterium Synechococcus PCC7942Plant Physiology, 1992
- A gene homologous to chloroplast carbonic anhydrase (icfA) is essential to photosynthetic carbon dioxide fixation by Synechococcus PCC7942.Proceedings of the National Academy of Sciences, 1992
- Identification of a genomic region that complements a temperature-sensitive, high CO2-requiring mutant of the cyanobacterium, Synechococcus sp. PCC7942Molecular Genetics and Genomics, 1991
- Biosynthesis of carbonic anhydrase in Chlamydomonas reinhardtii during adaptation to low CO 2Proceedings of the National Academy of Sciences of the United States of America, 1984
- Regulation of Chloroplastic Carbonic AnhydrasePlant Physiology, 1983
- THE CARBON-DIOXIDE HYDRATION ACTIVITY OF SKELETAL-MUSCLE CARBONIC-ANHYDRASE - INHIBITION BY SULFONAMIDES AND ANIONS1982
- Kinetic properties of ribulose 1,5-bisphosphate carboxylase/oxygenase from Anabaena variabilisArchives of Biochemistry and Biophysics, 1980
- Light-dependent changes of the Mg2+ concentration in the stroma in relation to the Mg2+ dependency of CO2 fixation in intact chloroplastsBiochimica et Biophysica Acta (BBA) - Bioenergetics, 1976
- Carbonic Anhydrase of SpinachPlant Physiology, 1975
- Spectrophotometric characteristics of chlorophylls a and b and their phenophytins in ethanolBiochimica et Biophysica Acta (BBA) - Biophysics including Photosynthesis, 1965