%0 Journal Article %A Röder, Richard %A Pfeifer, Felicitas %T Influence of salt on the transcription of the gas-vesicle genes of Haloferax mediterranei and identification of the endogenous transcriptional activator gene %D 1996 %J Microbiology, %V 142 %N 7 %P 1715-1723 %@ 1465-2080 %R https://doi.org/10.1099/13500872-142-7-1715 %K gas-vesicle genes %K Haloferax mediterranei %K transcriptional activator %K archaea %K gene regulation %I Microbiology Society, %X 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 mRNA and large amounts of 1.3 kb and 0.45 kb partial 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. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/13500872-142-7-1715