Replication Past the 𝛾-Radiation-Induced Guanine-Thymine Cross-Link G[8,5-Me]T by Human and Yeast DNA Polymerase 𝜂

Table 2

Kinetic parameters for dCTP and dATP incorporation and chain extension by yeast DNA polymerase η (6.4 nM) on an undamaged and G[8,5-Me]T cross-link containing substrate.

dNTP	𝑘cat (min^-1)	𝐾m (𝜇M)	𝑘cat/𝐾m (𝜇M^-1 min^-1)	𝐹ainc	X:G	𝑘cat (min^-1)	𝐾m (𝜇M)	𝑘cat/𝐾m (𝜇M^-1 min^-1)	𝐹aext
5^-GTGCĜ‌TGTTTGTATCGCTTGCAGGGG-3^					5^-GTGCĜ‌TGTTTGTATCGCTTGCAGGGG-3^
ACAAACATAGCGAACp32					X ACAAACATAGCGAACp32
Nucleotide Incorporation					Chain Extension^b
Undamaged substrate
dCTP	7.3 ± 0.02	0.04 ± 0.002	182.5	1.0	C:G	4.4 ± 0.04	0.07 ± 0.001	62.8	1.0
dATP	5.3 ± 0.03	9.5 ± 0.002	0.56	3.1 × 10^-3	A:G	3.7 ± 0.04	1.3 ± 0.01	2.8	4.4 × 10^-2
G[8,5-Me]T-containing substrate
dCTP	1.99 ± 0.001	11.2 ± 0.01	0.17	9.3 × 10^-4	C:G*	1.6 ± 0.1	0.31 ± 0.002	5.2	8.2 × 10^-2
dATP	2.2 ± 0.01	0.59 ± 0.005	3.72	2.0 × 10^-2	A:G*	1.2 ± 0.009	22.0 ± 1.0	0.05	7.9 × 10^-4

^aFidelity (𝐹) of incorporation or extension was determined by the following equation: (𝑘_cat/𝐾_m)_incorrect/(𝑘_cat/𝐾_m)_correct.
^bSteady-state kinetics for dGTP incorporation opposite C immediately following the X:G or X:G* pair was determined.