Complementation studies with the gas vesicle-encoding p-vac region of Halobacterium salinarium PHH1 reveal a regulatory role for the p-gvpDE genes.
Gas-vesicle (Vac) synthesis in Halobacterium salinarium PHH1 involves the expression of the p-vac region consisting of 14 different gvp genes that are arranged in two clusters: p-gvpACNO and, oppositely oriented, p-gvpDEFGHIJKLM. The latter cluster of genes is transcribed as two units: p-gvpDE and p-gvpF-M. The 5'-terminus of the p-gvpF-M mRNA was located 169 nucleotides upstream of p-gvpF within p-gvpE. The p-gvpG and p-gvpK gene was expressed in Escherichia coli and antibodies to proteins obtained were raised in rabbits. Both proteins could be detected in halobacterial cell lysates; in gas-vesicle preparations, however, neither GvpG nor GvpK could be found. The requirement for single p-gvp gene expression for gas-vesicle synthesis was determined by transformation experiments using the Vac- species Haloferax volcanii as recipient. Construct delta A containing all p-gvp genes except for p-gvpA, encoding the major gas-vesicle structural protein, produced Vac- transformants, but the addition of p-gvpA on a second vector restored gas-vesicle synthesis to wild-type level (Vac++). Similarly, double transformants containing p-gvpD-M plus p-gvpACNO, or p-gvpG-M (fused to the promoter of the halobacterial ferredoxin gene for expression) plus p-gvpFED-ACNO were Vac++. Transformants containing the p-vac region either lacking gvpA, gvpF, or gvpGHI were Vac-, indicating the absolute requirement of these gvp genes (or at least one in the case of gvpGHI) for gas-vesicle formation. Double transformants containing the constructs p-gvpF-M plus p-gvpACNO (delta DE) accumulated gas vesicles (Vac+) but synthesized fewer than the wild type, showing that the p-gvpDE genes are not necessary for gas-vesicle assembly. A repressor function affecting the synthesis of the p-gvpF-M mRNA could be suggested for p-gvpD and the 5'-region of its mRNA.
Offner
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S
Max-Planck-Institut für Biochemie, Martinsried, Germany.
Pfeifer
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D019843:Archaeal Proteins; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D016384:Consensus Sequence; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006217:Halobacterium / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D011506:Proteins; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D014169:Transformation, Bacterial
D019843:Archaeal Proteins; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D008565:Membrane Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; C038524:gas vesicle protein