Zinc finger proteins of the archaebacterial origin

Amino acid sequences that are likely to compose zinc finger domains of the C2H2 type are identified in some archaebacterial proteins by using the prev iously reported genomic DNA sequences. A synthetic peptide that is composed of the same 29 amino acid residues as in one of the putative zinc finger d omains binds the zinc ion at the 1:1 ratio, and thereby changes the conform ation. The peptide shows overall physico-chemical characteristics which are similar to the overall characteristics of another peptide of an eukaryotic protein sequence, that has been proved to fold into the standard zinc fing er structure. The archaebacterial peptide keeps binding the zinc ion even i n the presence of guanidine hydrochloride at a high concentration, while th e eukaryotic peptide looses the zinc ion at the same condition. Possible bi ological functions of the archaebacterial zinc finger proteins are discusse d.