DELETION ANALYSIS OF THE CHE OPERON IN THE ARCHAEON HALOBACTERIUM-SALINARIUM

Halobacterium salinarium is a chemo- and phototactic archaeon whose si gnal transduction pathway includes the classical two-component system made up of CheA and CheY. Deletion analysis of the che operon in H. sa linarium has been undertaken. Following the removal of the entire oper on, the importance of each of the four individual members, cheY, cheB, cheA, and the novel member cheJ, was evaluated by their replacement i n combinations of three. The mutant strains were investigated for thei r motility, their chemo- and phototactic signalling, and the rotationa l bias of their flagella. Loss of cheA, cheY or cheB fed to the comple te loss of chemo- and phototaxis, whereas the absence of cheJ caused a reduction in chemo- and phototactic ability Reverse swimming and coun terclockwise rotation of the flagella required the presence of cheA an d CheY. The wild-type 50:50 distribution of forward and reverse swimmi ng was observed in the strain lacking cheB, whereas this distribution was perturbed to 88:12 in the strain lacking cheJ. These results are c ompared with the corresponding deletion strains in Escherichia coli an d provide new insights into the eu- and archeabacterial flagellar swit ch. (C) 1996 Academic Press Limited