Influence of the RNase H domain of retroviral reverse transcriptases on the metal specificity and substrate selection of their polymerase domains

Table 1 Polymerase Activity of the Wild-Type and Chimeric Reverse Transcriptase

Percentage of Wild-Type HIV-1 RT Polymerase Activity
Enzyme	Poly (rA).(dT)₁₈		U5-PBS RNA/17mer DNA		U5-PBS 49mer DNA/17mer DNA
	Mg²⁺	Mn²⁺	Mg²⁺	Mn²⁺	Mg²⁺	Mn²⁺
WT HIV-1 RT	100 (22649)	100 (6182)	100 (4500)	100 (3740)	100 (2721)	100 (2451)
Chimeric HIV-1 RT	24	96	91	69	46	58
WT MuLV RT	130	331	71	95	58	68
Chimeric MuLV RT	80	477	108	183	81	72
MuLV RT- Pol Domain	88	221	65	68	48	52

The polymerase activities of wild-type reverse transcriptase enzymes and their chimeric derivatives were determined on homopolymeric and heteropolymeric template primers in the presence of Mg²⁺ or Mn²⁺ as the divalent cation. The values represent the percentage of WT HIV-1 RT activity. Data shown are the average of three independent experiments. The values in parentheses are the total cpm of acid-insoluble dNMP incorporated into the primer DNA by 100 ng of the WT HIV-1 RT at 37°C in 15 min. These determinations were done at saturating substrate concentrations (500 μM of each dNTP).

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