Since DNA contains the genetic information of an organism, accurate DNA replication is one of the most important events of the life cycle of an organism. DNA polymerases are key enzymes catalyzing the accurate replication of DNA.
DNA polymerases have been classified, based on their amino acid sequence similarities, into two major groups:
family A and family B. The family B DNA polymerases share regions of highly conserved amino acid sequeences. These conserved regions occur in the same order in all family B DNA polymerases molecules. Therefore, it is likely that these sequence conservations are a consequence of their contribution to the DNA polymerase function and structure.
However, little is known at present about functional roles of these highly conserved regions. To determine the functional roles of the highly conserved regions of the family B DNA polymerases, amino acid change generated in conserved regions by the site-directed mutagenesis. The results show that mutations at the conserved regions wi thin PRDI DNA polymerase inactvate polymeras^ complementing activity and catalytic activity.
A new conserved region between DNA poiymerase family A and B in the N-terminal portion has been identified which contains three highly conserved amino acids known to be involved in the 3´-5´ exonuclease active site of Klenow fragment of E. coli polymerase I.
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