scholarly journals Pre-Steady State Kinetic Studies of the Fidelity of Nucleotide Incorporation by Yeast DNA Polymerase δ

Biochemistry ◽  
2010 ◽  
Vol 49 (34) ◽  
pp. 7344-7350 ◽  
Author(s):  
Lynne M. Dieckman ◽  
Robert E. Johnson ◽  
Satya Prakash ◽  
M. Todd Washington
Keyword(s):  
Steady State ◽  
Dna Polymerase ◽  
Kinetic Studies ◽  
Dna Polymerase Δ ◽  
Nucleotide Incorporation ◽  
Steady State Kinetic ◽  
State Kinetic

Pre-Steady-State Kinetic Studies of the Fidelity of Human DNA Polymerase μ†

Biochemistry ◽  
2004 ◽  
Vol 43 (43) ◽  
pp. 13827-13838 ◽  
Author(s):  
Michelle P. Roettger ◽  
Kevin A. Fiala ◽  
Susmitha Sompalli ◽  
Yuxia Dong ◽  
Zucai Suo
Keyword(s):  
Steady State ◽  
Dna Polymerase ◽  
Kinetic Studies ◽  
Human Dna ◽  
Steady State Kinetic ◽  
State Kinetic

scholarly journals The Mechanism of Nucleotide Incorporation by Human DNA Polymerase η Differs from That of the Yeast Enzyme

2003 ◽  
Vol 23 (22) ◽  
pp. 8316-8322 ◽  
Author(s):  
M. Todd Washington ◽  
Robert E. Johnson ◽  
Louise Prakash ◽  
Satya Prakash
Keyword(s):  
Steady State ◽  
Dna Polymerase ◽  
Kinetic Studies ◽  
Variant Form ◽  
Low Level ◽  
Human Enzyme ◽  
Pyrimidine Dimers ◽  
Nucleotide Incorporation ◽  
Steady State Kinetic ◽  
Mechanistic Basis

ABSTRACT DNA polymerase η (Polη) catalyzes the efficient and accurate synthesis of DNA opposite cyclobutane pyrimidine dimers, and inactivation of Polη in humans causes the cancer-prone syndrome, the variant form of xeroderma pigmentosum. Pre-steady-state kinetic studies of yeast Polη have indicated that the low level of fidelity of this enzyme results from a poorly discriminating induced-fit mechanism. Here we examine the mechanistic basis of the low level of fidelity of human Polη. Because the human and yeast enzymes behave similarly under steady-state conditions, we expected these enzymes to utilize similar mechanisms of nucleotide incorporation. Surprisingly, however, we find that human Polη differs from the yeast enzyme in several important respects. The human enzyme has a 50-fold-faster rate of nucleotide incorporation than the yeast enzyme but binds the nucleotide with an approximately 50-fold-lower level of affinity. This lower level of binding affinity might provide a means of regulation whereby the human enzyme remains relatively inactive except when the cellular deoxynucleoside triphosphate concentrations are high, as may occur during DNA damage, thereby avoiding the mutagenic consequences arising from the inadvertent action of this enzyme during normal DNA replication.

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