Obiettivo
The Na+ cycle, novel type of the cellular energetics will be investigated in several bacterial species. To this end, bacteria will be grown under conditions unfavourable for operation of the classical H+ cycle. The delta uNa+ -generating and (uNa+ -utilising enzymes will be isolated and reconstituted into proteoliposomes. Among them will be: cytochrome d, a putative Na+ - motive terminal oxidase of E. coli; the E. coli Na+ -ATP-synthase, which is assumed to be a modified H+ -ATP-synthase of F-type, and the Clostridium fervidus Na+ -ATPase of V-type.
Some approaches to the understanding of the mechanisms of the Na+ pumping by these enzymes will be analysed. Moreover, a sequence of genes encoding for the Vibrio alginolyicus Na+-motive NADH-quinone oxidase will be done. Using the sequence, an attempt will be made to find corresponding genes in E. coli. In marine cyanobacteria, a search for the Na+ - motive Q-cycle included into the photeredox chain will be carried out.
The control mechanism(s) responsible for the H+-to-Na+ switch will be studied. In this part of the work the promoter (delta uH+ -sensor) and sodimeter (deltaNa+-sensor) hypotheses will be tested. Involvement of the Arc system in the switch and repellent action of the delta uH+-lowering effectors will be studied. The regulation in question will be compared in E. coli and Rhodobacter sphaeroides deferring in the mechanisms of the signal processing. In Halobacterium salinarium an attempt will be made to select mutants deficient in protometer. In E. coli the possible role of sodiometer in the H+-to-Na+ switch will be investigated.
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PL30 4AU Bodmin
Regno Unito