Danish Archaea Centre, Institute of Molecular Biology, University of Copenhagen, Sølvgade 83H, DK-1307 Copenhagen K, Denmark. brugger@mermaid.molbio.ku.dk|Danish Archaea Centre, Institute of Molecular Biology, University of Copenhagen, Sølvgade 83H, DK-1307 Copenhagen K, Denmark. brugger@mermaid.molbio.ku.dk|Danish Archaea Centre, Institute of Molecular Biology, University of Copenhagen, Sølvgade 83H, DK-1307 Copenhagen K, Denmark. brugger@mermaid.molbio.ku.dk