The E89C alteration in the human immunodeficiency virus type 1 reverse transcriptase has been shown to confer resistance to nucleoside analogs and a loss of magnesium cation preference (Prasad, V. R., Lowy, I., De Los Santos, T., Chiang, L., and Goff, S. P. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 11363-11367. The wild type reverse transcriptase heterodimer, chimeric reverse transcriptases that contain the E89G alteration in one of the subunits (p66(wt)/p51m and p66m/p51(wt)), and the mutant enzyme (p66m/p51m) were prepared. Analysis of steady state kinetic parameters showed that the mutant enzyme (p66m/p51m) displayed a higher V(max), a higher K(m) for 2'-deoxythymidine triphosphate, and a higher K(i) for 2',3'- dideoxythymidine triphosphate than the wild type enzyme. The increased K(m) and K(i) values were observed only when a heterodimer contained the alteration in the p66 subunit. Tests for divalent cation requirement showed that only the dimers containing the wild type p66 (p66(wt)/p51(wt) and p66(wt)/p51m) displayed a preference for magnesium. Our results indicate that p66 plays a dominant role in deoxynucleotide triphosphate substrate recognition (K(m)), nucleoside analog sensitivity (K(i)), and magnesium preference. However, the increased V(max) displayed by the mutant enzyme (p66m/p51m) appeared to be determined by both of the subunits.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|State||Published - Jan 1 1994|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology