Identification of the mcrC gene product in Methanococcus vannielii

The polypeptide encoded by the mcrC gene has been identified in Methanococcus vannielii by immunoblotting using rabbit antibodies raised against the product of a lacZ-mcrC gene fusion synthesized and purified from Escherichia coli. The mcrC gene product (gpmcrC) was located in both the supernatant and pellet fractions after centrifugation of Mc. vannielii cell extracts for 2 h at 100,000 x g. When anaerobic reducing conditions were maintained during purification, gpmcrC co-sedimented through sucrose gradients to the same position as molecules of the methyl coenzyme M reductase holoenzyme (approx. 300 kDa). This co-sedimentation was lost under aerobic, nonreducing conditions.