2alz
From Proteopedia
Ternary Complex of hPoli with DNA and dCTP
Overview
Human DNA polymerase iota (hPoliota), a member of the Y family of DNA polymerases, differs in remarkable ways from other DNA polymerases, incorporating correct nucleotides opposite template purines with a much higher efficiency and fidelity than opposite template pyrimidines. We present here the crystal structure of hPoliota bound to template G and incoming dCTP, which reveals a G.C + Hoogsteen base pair in a DNA polymerase active site. We show that the hPoliota active site has evolved to favor Hoogsteen base pairing, wherein the template sugar is fixed in a cavity that reduces the C1'-C1' distance across the nascent base pair from approximately 10.5 A in other DNA polymerases to 8.6 A in hPoliota. The rotation of G from anti to syn is then largely in response to this curtailed C1'-C1' distance. A G.C+ Hoogsteen base pair suggests a specific mechanism for hPoliota's ability to bypass N(2)-adducted guanines that obstruct replication.
About this Structure
2ALZ is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Human DNA polymerase iota incorporates dCTP opposite template G via a G.C + Hoogsteen base pair., Nair DT, Johnson RE, Prakash L, Prakash S, Aggarwal AK, Structure. 2005 Oct;13(10):1569-77. PMID:16216587 Page seeded by OCA on Sat May 3 19:12:16 2008
