CHARACTERIZATION OF A NEW DNA-POLYMERASE FROM SCHIZOSACCHAROMYCES-POMBE - A PROBABLE HOMOLOG OF THE SACCHAROMYCES-CEREVISIAE DNA-POLYMERASE-GAMMA

Mitochondrial (mt) DNA replication is carried out by the nuclear-encod ed DNA polymerase-gamma (Pol-gamma). We have cloned a new DNA polymera se-encoding gene from Schizossaccharomyces pombe (Sp), which we believ e encodes the homologue of the Saccharomyces cerevisiae (Sc) mt DNA po lymerase (MIP1). The putative Sp poly gene expressed a transcript of a pprox. 4-kb that contained a 3-kb open reading frame encoding a polype ptide of 1018 amino acids (aa) (116kDa). This Sp Pol-gamma is 48% iden tical to the Sc MIP1 and contains uniquely conserved regions not found in the bacterial Poll-type DNA polymerases. The most notable differen ce between these two proteins is that the MIP1 product has a 236-aa C- terminal region beyond motif C that is not found in Sp Pol-gamma. Chro mosomal mapping and genomic sequencing of the Sp poly places this gene on chromosome III downstream from the triose phosphate isomerase-enco ding gene.