The hyperthermophilic archaeon Pyrodictium occultum has two alpha-like DNA polymerases.
AUTOR(ES)
Uemori, T
RESUMO
We cloned two genes encoding DNA polymerases from the hyperthermophilic archaeon Pyrodictium occultum. The deduced primary structures of the two gene products have several amino acid sequences which are conserved in the alpha-like (family B) DNA polymerases. Both genes were expressed in Escherichia coli, and highly purified gene products, DNA polymerases I and II (pol I and pol II), were biochemically characterized. Both DNA polymerase activities were heat stable, but only pol II was sensitive to aphidicolin. Both pol I and pol II have associated 5'-->3' and 3'-->5' exonuclease activities. In addition, these DNA polymerases have higher affinity to single-primed single-stranded DNA than to activated DNA; even their primer extension abilities by themselves were very weak. A comparison of the complete amino acid sequences of pol I and pol II with two alpha-like DNA polymerases from yeast cells showed that both pol I and pol II were more similar to yeast DNA polymerase III (ypol III) than to yeast DNA polymerase II (ypol II), in particular in the regions from exo II to exo III and from motif A to motif C. However, comparisons region by region of each polymerase showed that pol I was similar to ypol II and pol II was similar to ypol III from motif C to the C terminus. In contrast, pol I and pol II were similar to ypol III and ypol II, respectively, in the region from exo III to motif A. These findings suggest that both enzymes from P. occultum play a role in the replication of the genomic DNA of this organism and, furthermore, that the study of DNA replication in this thermophilic archaeon may lead to an understanding of the prototypical mechanism of eukaryotic DNA replication.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=176862Documentos Relacionados
- The DNA polymerase gene from the hyperthermophilic marine archaebacterium, Pyrococcus furiosus, shows sequence homology with alpha-like DNA polymerases.
- Aphidicolin inhibits DNA polymerase II of Escherichia coli, an alpha-like DNA polymerase.
- Antigenic Determinants of Alpha-Like Proteins of Streptococcus agalactiae
- Engineered herpes simplex virus DNA polymerase point mutants: the most highly conserved region shared among alpha-like DNA polymerases is involved in substrate recognition.
- Mosaicism in the alpha-like protein genes of group B streptococci