Selenium is involved in the negative regulation of the expression of selenium-free [NiFe] hydrogenases in Methanococcus voltae.

Competitive polymerase chain reactions (PCR) were used to analyze quantitatively the transcription patterns of the four different gene groups encoding [NiFe] hydrogenases in Methanococcus voltae. In cells growing in the presence of selenium, transcripts of only two of the hydrogenase transcription units could be detected in quantities above background levels. The missing transcripts encode the selenium-free F420-non-reducing and F420-reducing hydrogenases. In cells grown without selenium these transcripts are detectable, indicating the involvement of selenium in their transcriptional regulation.