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Table 1 The contribution of the trigger loop compared in the E. coli and the T. aquaticus studies

From: The architecture of RNA polymerase fidelity

T. aquaticusmutation [2] Substrate/fold defect relative to WT (kpol[cGTP]) E. colimutation [9] Substrate/fold defect relative to WT (kCTP25 μM)
Arg1239Ala GTP/~48 Arg933Ala CTP/4
His1242Ala GTP/~100 His936Ala CTP/6
Arg1239Ala/His1242Ala GTP/~1400 Arg933Ala/His936 CTP/24
   Ala  
Met1238Ala GTP/~1800 Met932Ala CTP/70
ΔTL GTP/~62,500 TLLTPP* CTP/12,000
T. aquaticus mutation[2] Substrate/fold selectivity for cGTP E. coli mutation [9] Substrate/fold selectivity for cATP
WT kpolapp 2'-cdATP/~1800 WT kpolapp ND
WT Km 2'-cdATP/~20 WT Km ND
ΔTL kpolapp 2'-cdATP/~1.2 ΔTL kpolapp 2'-cdATP/~27
ΔTL Km 2'-cdATP/~1.4 ΔTL Km 2'-cdATP/~4
  1. ND = Not determined. kpolapp = apparent kpol. *TLLTPP is a double-proline substituted mutant in the E. coli TL proposed to compromised folding.