IDENTIFICATION AND ANALYSIS OF THE GAS VESICLE GENE-CLUSTER ON AN UNSTABLE PLASMID OF HALOBACTERIUM-HALOBIUM

In our efforts to elucidate the mechanism of high-frequency mutation o f Halobacterium halobium to a gas vesicle deficient state, we discover ed insertions, deletions, inversions, and complex DNA rearrangements a ssociated with a large endogenous plasmid, pNRC100. The rearrangements are mostly IS element-mediated, and when they occur in a region of pN CRC100 containing a cluster of thirteen genes, gas vesicle mutants res ult. We have characterized the structure and expression of this gas ve sicle protein (gvp) gene cluster and demonstrated its requirement for gas vesicle synthesis and cell flotation by genetic transformation.