Influence of salt on the transcription of the gas-vesicle genes of Haloferax mediterranei and identification of the endogenous transcriptional activator gene.
The transcription of the 14 gvp genes of the gas-vesicle-encoding mc-vac region was investigated, using RNA from 25% and 15% (w/v) salt cultures of the moderately halophilic archaeon Haloferax mediterranei. Transcription occurred only from two promoters, located in front of the mc-gvpA and mc-gvpD genes. In both cultures transcripts spanning the entire mc-gvpDEFGHIJKLM transcription unit were formed only during the exponential growth phase. Amounts of these transcripts were larger in the 25% salt culture, in which the 2.0 kb mc-gvpD transcripts were also synthesized during the stationary phase. The levels of the mc-gvpD transcripts and of the 324 nt mc-gvpA mRNA increased in parallel during the stationary phase of the 25% salt culture. Only under these conditions were mRNAs spanning the entire mc-gvpACNO transcription unit observed, and gas-vesicles were formed. Investigation of the influence of the mc-gvpDE genes on both mc-vac promoters in transformants revealed that by themselves they were nearly inactive. The addition of mc-gvpE, however, resulted in a high level of constitutively produced mc-gvpA and mc-gvpD mRNA, indicating a transcriptional activator function for the mc-gvpE product.
Röder
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Institut für Mikrobiologie, TH Darmstadt, Germany.
Pfeifer
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D019843:Archaeal Proteins; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001483:Base Sequence; D002874:Chromosome Mapping; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005798:Genes, Bacterial; D006216:Halobacteriaceae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D011506:Proteins; D012329:RNA, Bacterial / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D015534:Trans-Activators; D014158:Transcription, Genetic / Q000187:drug effects
D019843:Archaeal Proteins; D001425:Bacterial Outer Membrane Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D008565:Membrane Proteins; D011506:Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D015534:Trans-Activators; C038524:gas vesicle protein; D012965:Sodium Chloride