Selective extraction of subunit D of the Na+-translocating methyltransferase and subunit c of the A(1)A(0) ATPase from the cytoplasmic membrane of methanogenic archaea by chloroform/methanol and characterization of subunit cof Methanothermobacter thermoautotrophicus as a 16-kDa proteolipid

Chloroform/methanol was applied to cytoplasmic membranes of the thermophili c methanogens Methanothermobacter thermoautotrophicus and Methanothermobact er marburgensis as well as to the mesophile Methanosarcina mazei Gol. In an y case, the chloroform/methanol extraction yielded only two proteins, subun it D (MtrD) of the Na+-translocating methylterrahydromethanopterin:coenzyme M methyltransferase and the proteolipid of the A(1)A(0) ATPase. Both polyp eptides are assumed to be directly involved in ion translocation in their r espective enzymes. but have not been studied in derail due to lack of simpl e isolation procedures. The rapid and selective isolation by chloroform/met hanol offers a new way to obtain the large quantities of material required for biochemical analyses. As a first result, molecular and biochemical data suggest that the proteolipid from M. thermoautotrophicus is a duplication of the 8-kDa proteolipid usually present in other archaea, but it retained the conserved glutamate involved in proton translocation in every copy. Thi s is the first 16-kDa proteolipid found in archaea. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.