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

Table 1

Kinetic parameters for dCTP and dATP incorporation and chain extension by human 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	7.6 ± 0.1	0.02 ± 0.003	380	1.0	C:G	3.9 ± 0.2	0.09 ± 0.005	43.4	1.0
dATP	6.25 ± 0.01	6.5 ± 0.03	0.96	2.5 × 10^-3	A:G	4.7 ± 0.1	5.1 ± 0.03	0.9	2.1 × 10^-2
G[8,5-Me]T-containing substrate
dCTP	2.43 ± 0.02	0.11 ± 0.002	22.1	5.8 × 10^-2	C:G*	2.0 ± 0.02	0.24 ± 0.004	8.3	0.2
dATP	1.75 ± 0.1	1.07 ± 0.01	1.63	4.2 × 10^-3	A:G*	1.7 ± 0.01	2.6 ± 0.03	0.65	1.5 × 10^-2

^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.