Molecular Biology of the Extremely Thermophilic Archaebacteria 'Methanothermus fervidus'

摘要

A DNA binding protein, designated HMf, and DNA dependent RNA polymerase (RNAP) have been isolated and characterized from the extremely thermophilic methanogen Methanothermus fervidus. Binding of HMf to double-stranded DNA increases its thermal denaturation temperature by as much as 25 degs. The isolated RNAP is oxygen stable and has optimum activity at 60 degs in the presence of 350 mM K+. Addition of HMf at low protein: DNA ratios appears to increase transcription in vitro by the M. fervidus RNAP. Genes encoding the subunits of methyl coenzyme M reductase, non-F 420 -reducing hydrogenase, tRNAs and rRNAs have been cloned and sequenced from M. fervidus and are being used as templates for in vitro transcription by the M. fervidus RNAP. The M. fervidus mvhB gene appears to encode a polyferredoxin. The mvhb DNA sequence predicts that the encoded protein contains six tandemly-repeated bacterial ferredoxin ferredoxin domains. keywords: Archaebacteria, Anaerobes, Gene cloning Thermophiles, Methanogens, DNA sequences. (aw)