Solution structure of a viral DNA polymerase X and evidence for a mutagenic function.


The African swine fever virus DNA polymerase X (ASFV Pol X or Pol X), the smallest known nucleotide polymerase, has recently been reported to be an extremely low fidelity polymerase that may be involved in strategic mutagenesis of the viral genome. Here we report the solution structure of Pol X. The structure, unique within the realm of nucleotide polymerases, consists of only palm and fingers subdomains. Despite the absence of a thumb subdomain, which is important for DNA binding in other polymerases, we show that Pol X binds DNA with very high affinity. Further structural analyses suggest a novel mode of DNA binding that may contribute to low fidelity synthesis. We also demonstrate that the ASFV DNA ligase is a low fidelity ligase capable of sealing a nick that contains a G-G mismatch. This supports the hypothesis of a virus-encoded, mutagenic base excision repair pathway consisting of a tandem Pol X/ligase mutator.



Structure and Structure/Function, Source / Purification


new topics/pols set partial results complete validated


Polymerase Reference Property Result Context
ASFV pol X Showalter AK2001 Polymerase Catalytic Residue Amino Acids Asp 49, 51 and 100
ASFV pol X Showalter AK2001 Cloned or native Cloned in E. coli
ASFV pol X Showalter AK2001 Tagged No
ASFV pol X Showalter AK2001 Full length or truncated Full length

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