An incoming nucleotide imposes an anti to syn conformational change on the templating purine in the human DNA polymerase-iota active site.
Substrate-induced conformational change of the protein is the linchpin of enzymatic reactions. Replicative DNA polymerases, for example, convert from an open to a closed conformation in response to dNTP binding. Human DNA polymerase-iota (hPoliota), a member of the Y family of DNA polymerases, differs strikingly from other polymerases in its much higher proficiency and fidelity for nucleotide incorporation opposite template purines than opposite template pyrimidines. We present here a crystallographic analysis of hPoliota binary complexes, which together with the ternary complexes show that, contrary to replicative DNA polymerases, the DNA, and not the polymerase, undergoes the primary substrate-induced conformational change. The incoming dNTP "pushes" templates A and G from the anti to the syn conformation dictated by a rigid hPoliota active site. Together, the structures posit a mechanism for template selection wherein dNTP binding induces a conformational switch in template purines for productive Hoogsteen base pairing.
Nair
Deepak T
DT
Structural Biology Program, Department of Physiology and Biophysics, Mount Sinai School of Medicine, Box 1677, 1425 Madison Avenue, New York, New York 10029, USA.
Johnson
Robert E
RE
Prakash
Louise
L
Prakash
Satya
S
Aggarwal
Aneel K
AK
D020029:Base Pairing; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry*; D005982:Glutathione Transferase / Q000378:metabolism; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D009711:Nucleotides / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011687:Purines / Q000737:chemistry; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D000094769:DNA Polymerase iota
D009711:Nucleotides; D011687:Purines; D011993:Recombinant Fusion Proteins; D004247:DNA; D005982:Glutathione Transferase; D004259:DNA-Directed DNA Polymerase; D000094769:DNA Polymerase iota