Error rate and specificity of human and murine DNA polymerase eta.

Abstract:

We describe here the error specificity of mammalian DNA polymerase eta (pol eta), an enzyme that performs translesion DNA synthesis and may participate in somatic hypermutation of immunoglobulin genes. Both mouse and human pol eta lack intrinsic proofreading exonuclease activity and both copy undamaged DNA inaccurately. Analysis of more than 1500 single-base substitutions by human pol eta indicates that error rates for all 12 mismatches are high and variable depending on the composition and symmetry of the mismatch and its location. pol eta also generates tandem base substitutions at an unprecedented rate, and kinetic analysis indicates that it extends a tandem double mismatch about as efficiently as other replicative enzymes extend single-base mismatches. This ability to use an aberrant primer terminus and the high rate of single and double-base substitutions support the idea that pol eta may forego strict shape complementarity in order to facilitate highly efficient lesion bypass. Relaxed discrimination is further indicated by pol eta infidelity for a wide variety of nucleotide deletion and addition errors. The nature and location of these errors suggest that some may be initiated by strand slippage, while others result from additional mechanisms.

Polymerases:

Topics:

Fidelity, Exonuclease Activity, Source / Purification, Nucleotide Incorporation

Status:

new topics/pols set partial results complete validated

Results:

Polymerase Reference Property Result Context
Mouse Pol eta Matsuda T2001 3-5' Exonuclease (proofreading) No
Mouse Pol eta Matsuda T2001 Cloned or native Insect cells
Mouse Pol eta Matsuda T2001 Tagged Yes
Mouse Pol eta Matsuda T2001 Tag Name C-terminal His
Mouse Pol eta Matsuda T2001 Nucleotide Substitution Rate 0.022 errors/bp Technique: M13mp2 forward mutation assay
Mouse Pol eta Matsuda T2001 Full length or truncated Full length
Mouse Pol eta Matsuda T2001 Gap Filling Yes
Human Pol eta Matsuda T2001 3-5' Exonuclease (proofreading) No
Human Pol eta Matsuda T2001 Cloned or native Insect cells
Human Pol eta Matsuda T2001 Tagged Yes
Human Pol eta Matsuda T2001 Tag Name C-terminal His
Human Pol eta Matsuda T2001 Nucleotide Substitution Rate 0.032 errors/bp Technique: M13mp2 forward mutation assay
Human Pol eta Matsuda T2001 Full length or truncated Full length
Human Pol eta Matsuda T2001 Gap Filling Yes

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