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CyaC, a redox‐regulated adenylate cyclase of Sinorhizobium meliloti with a quinone responsive diheme‐B membrane anchor domain
Author(s) -
Wissig Juliane,
Grischin Julia,
Bassler Jens,
Schubert Christopher,
Friedrich Thorsten,
Bähre Heike,
Schultz Joachim E.,
Unden Gottfried
Publication year - 2019
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14251
Subject(s) - biology , adenylate kinase , cyclase , biochemistry , histidine , sinorhizobium meliloti , heme , escherichia coli , membrane protein , membrane , enzyme , mutant , gene
Summary The nucleotide cyclase CyaC of Sinorhizobium meliloti is a member of class III adenylate cyclases (AC), a diverse group present in all forms of life. CyaC is membrane‐integral by a hexahelical membrane domain (6TM) with the basic topology of mammalian ACs. The 6TM domain of CyaC contains a tetra‐histidine signature that is universally present in the membrane anchors of bacterial diheme‐B succinate‐quinone oxidoreductases. Heterologous expression of cyaC imparted activity for cAMP formation from ATP to Escherichia coli, whereas guanylate cyclase activity was not detectable. Detergent solubilized and purified CyaC was a diheme‐B protein and carried a binuclear iron‐sulfur cluster. Single point mutations in the signature histidine residues caused loss of heme‐B in the membrane and loss of AC activity. Heme‐B of purified CyaC could be oxidized or reduced by ubiquinone analogs (Q 0 or Q 0 H 2 ). The activity of CyaC in bacterial membranes responded to oxidation or reduction by Q 0 and O 2 , or NADH and Q 0 H 2 respectively. We conclude that CyaC‐like membrane anchors of bacterial ACs can serve as the input site for chemical stimuli which are translated by the AC into an intracellular second messenger response.