Topoisomerase activity of the hyperthermophilic replication initiator protein Rep75
AUTOR(ES)
Marsin, Stéphanie
FONTE
Oxford University Press
RESUMO
The plasmid pGT5 from the hyperthermophilic archaeon Pyrococcus abyssi replicates via the rolling circle mechanism. pGT5 encodes the replication initiator protein Rep75 that exhibits a nicking–closing (NC) activity in vitro on single-stranded oligonucleotides containing the pGT5 double-stranded origin (dso) sequence. Some mesophilic Rep proteins present site-specific DNA topoisomerase-like activity on a negatively supercoiled plasmid harbouring the dso. We report here that Rep75 also exhibits topoisomerase activity on a negatively supercoiled DNA substrate. This DNA topoisomerase-like activity is dependent on the amino acids involved in NC activity of Rep75. However, in contrast with mesophilic Rep proteins, Rep75 topoisomerase activity is not dso dependent. Moreover, although pGT5 is known to be relaxed in vivo, Rep75 was not able to act on a relaxed plasmid in vitro, whether or not it contained the dso.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=102634Documentos Relacionados
- Uncoupling of the DNA topoisomerase and replication activities of an initiator protein.
- Plasmid replication initiator protein RepD increases the processivity of PcrA DNA helicase.
- Replication initiator protein RepE of mini-F plasmid: functional differentiation between monomers (initiator) and dimers (autogenous repressor).
- Replication origin mutations affecting binding of pSC101 plasmid-encoded Rep initiator protein.
- The replication initiator protein of plasmid pT181 has sequence-specific endonuclease and topoisomerase-like activities.