Functional analysis of novel selective mutants of the reverse transcriptase of human immunodeficiency virus type 1

• Published in: The Journal of biological chemistry Vol. 267; no. 26; pp. 18255 - 18258
• Main Authors: HIZI, A, SHAHARABANY, M
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 15.09.1992
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; DNA-Directed DNA Polymerase - metabolism; Electrophoresis, Polyacrylamide Gel; Enzymes and enzyme inhibitors; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression; HIV-1 - enzymology; Mutagenesis, Site-Directed; Plasmids; Ribonuclease H - metabolism; RNA-Directed DNA Polymerase - genetics; RNA-Directed DNA Polymerase - metabolism; Transferases; HIV-1 virus; Enzyme; Site directed mutagenesis; Retroviridae; Proline; Virus; Polymerase chain reaction; Enzymatic activity; Structure activity relation; DNA polymerase RNA-dependent; Lentivirinae; Replication; Human immunodeficiency virus
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)36950-9

We have generated by site-directed mutagenesis plasmids that induce the synthesis of specific mutants of the reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1). These recombinant mutants of HIV-1 RT, designed on the basis of our previous studies of HIV-1 and HIV-2 RTs, were analyzed for structure-function relationship by assessing their RNA-dependent and DNA-dependent DNA polymerase as well as the ribonuclease H activities. Three groups of mutants were studied. 1) We have investigated the importance of the only two sets of highly conserved double prolines found in the sequence of HIV-1 RT. The results indicate that the conversion of either one or both prolines (at positions 225 and 226) to threonines have no significant effect on all catalytic activities of the enzyme. The mutants in which prolines 419 and 420 were individually modified to threonines exhibit full activities, whereas the double proline 419/420 mutant lost most of its RNase H activity (although the DNA polymerase function was fully retained). 2) We have deleted phenylalanine 346 from HIV-1 RT, which is absent in wild type HIV-2 RT. This mutant of HIV-1 RT lost practically all catalytic activities. 3) A mutant of HIV-1 RT in which a cysteine residue substituted for alanine 446, was found to be slightly hyperactive for both DNA polymerase and RNase H activities.