FtsH protease is required for induction of inorganic carbon acquisition complexes in Synechocystis sp. PCC 6803

• Published in: Molecular microbiology Vol. 65; no. 3; pp. 728 - 740
• Main Authors: Zhang, Pengpeng, Sicora, Cosmin I, Vorontsova, Natalia, Allahverdiyeva, Yagut, Battchikova, Natalia, Nixon, Peter J, Aro, Eva-Mari
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.08.2007; Blackwell Publishing Ltd; Blackwell Science
• Subjects: Autoradiography; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biochemistry; Biological and medical sciences; Carbon Compounds, Inorganic - metabolism; Carbon dioxide; Carbon Dioxide - metabolism; Diuron - pharmacology; Environment; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial - drug effects; Genes, Bacterial; Inorganic carbon; Microbiology; Miscellaneous; Models, Biological; Mutants; Mutation - genetics; Oxidative stress; Paraquat - pharmacology; Photosynthesis; Proteases; Protein Biosynthesis - drug effects; Proteome - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Synechocystis - cytology; Synechocystis - drug effects; Synechocystis - enzymology; Synechocystis - genetics; Peptidases; Bacteria; Hydrolases; Synechocystis; Enzyme; Cyanobacteria
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2007.05822.x

Cyanobacteria possess a complex CO₂-concentrating mechanism (CCM), which is induced by low inorganic carbon conditions. To investigate the involvement of proteases in the processes of induction and degradation of the CCM complexes, we studied the FtsH2 (ΔSlr0228) and Deg-G (ΔSlr1204/ΔSll1679/ΔSll1427) protease mutants of Synechocystis sp. PCC 6803. WT and protease mutant cells were grown under high CO₂ and then shifted to low CO₂, followed by a proteome analysis of the membrane protein complexes. Interestingly, in the FtsH2 protease mutant, inducible CCM complexes were not detected upon shift to low CO₂, whereas the Deg-G mutant behaved like WT. Also the transcripts of the inducible CCM genes and their regulator ndhR failed to accumulate upon shift of FtsH2 mutant cells from high to low CO₂, indicating that the regulation by the FtsH2 protease is upstream of NdhR. Moreover, functional photosynthesis was shown a prerequisite for induction of CCM in WT at low CO₂, possibly via generation of oxidative stress, which was shown here to enhance the expression of inducible CCM genes even at high CO₂ conditions. Once synthesized, the CCM complexes were not subject to proteolytic degradation, even when dispensable upon a shift of cells to high CO₂.