Röder R, Pfeifer F
Institut für Mikrobiologie, TH Darmstadt, Germany.
Microbiology (Reading). 1996 Jul;142 ( Pt 7):1715-23. doi: 10.1099/13500872-142-7-1715.
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.
利用嗜盐古菌地中海富盐菌（Haloferax mediterranei）在25%和15%（w/v）盐浓度培养条件下获得的RNA，对编码气荚膜的mc-vac区域的14个gvp基因的转录情况进行了研究。转录仅发生在位于mc-gvpA和mc-gvpD基因之前的两个启动子处。在两种培养条件下，跨越整个mc-gvpDEFGHIJKLM转录单元的转录本仅在指数生长期形成。这些转录本在25%盐浓度培养条件下的含量更高，在该条件下，2.0 kb的mc-gvpD转录本在稳定期也会合成。在25%盐浓度培养条件的稳定期，mc-gvpD转录本和324 nt的mc-gvpA mRNA的水平平行增加。只有在这些条件下，才观察到跨越整个mc-gvpACNO转录单元的mRNA，并且形成了气荚膜。对转化体中mc-gvpDE基因对两个mc-vac启动子的影响进行研究发现，它们自身几乎没有活性。然而，添加mc-gvpE会导致组成型产生高水平的mc-gvpA和mc-gvpD mRNA，这表明mc-gvpE产物具有转录激活功能。
