Non-homologous end joining (NHEJ) is one of two pathways responsible for the repair of double-strand breaks in eukaryotic cells. The mechanism involves the alignment of broken DNA ends with minimal homology, fill in of short gaps by DNA polymerase(s), and ligation by XRCC4-DNA ligase IV complex. The gap-filling polymerase has not yet been positively identified, but recent biochemical studies have implicated DNA polymerase λ (pol λ), a novel DNA polymerase that has been assigned to the pol X family, in this process. Here we demonstrate that purified pol λ can efficiently catalyze gap-filling synthesis on DNA substrates mimicking NHEJ. By designing two truncated forms of pol λ, we also show that the unique proline-rich region in pol λ plays a role in limiting strand displacement synthesis, a feature that may help its participation in in vivo NHEJ. Moreover, pol λ interacts with XRCC4-DNA ligase IV via its N-terminal BRCT domain and the interaction stimulates the DNA synthesis activity of pol λ. Taken together, these data strongly support that pol λ functions in DNA polymerization events during NHEJ.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:etsu-works-19911 |
| Date | 29 October 2004 |
| Creators | Fan, Wei, Wu, Xiaoming |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Source | ETSU Faculty Works |
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