Isolation of a minD-like gene in the hyperthermophilic archaeon PyrococcusAL585, and phylogenetic characterization of related proteins in the three domains of life

The region upstream of the dinF-like gene of the hyperthermophilic archaeon Pyrococcus strain AL585 has been cloned and sequenced. This region contain s an open reading frame (ORF) that encodes a polypeptide with a high simila rity to MinD proteins and their Mrp paralogues. Transcripts of the dinF-lik e and the minD-like genes were detected by RT-PCR, indicating that they are both expressed in vivo. The MinD and MinD-like proteins belong to a broad family of ATPases involved in chromosome and plasmid partitioning. MinD-lik e proteins can be defined by specific amino-acid sequence signatures. A sys tematic search for proteins sharing these signatures in current databases a nd newly sequenced genomes show that MinD-like proteins are present in all archaeal genomes sequenced so far, often in several copies. Phylogenetic an alysis identifies two groups of MinD-like proteins which are also character ized by more conserved amino-acid motifs. A first group, which includes the Escherichia coli MinD and the Pyrococcus AL585 MinDL protein, contains onl y procaryotic proteins. This group can be further divided into a subgroup o f archaeal proteins and two subgroups of bacterial proteins. A second group includes proteins more related to the E. coli Mrp protein and contains rep resentants of the three domains of life. The conservation of MinD-like prot eins in the three domains of life suggests that these proteins play a centr al role in cellular metabolism. (C) 1998 Elsevier Science B.V. All rights r eserved.