title: Mutational analysis of the "turn" of helix clamp motif of HIV-1 reverse transcriptase.
abstract: Helix clamp motifs of polymerases possessing the helix-turn-helix secondary structure are crucial for their polymerase activity by binding to the nucleic acid template/primer via the alpha helices. To study the functions of turn in helix clamp motif of human immunodeficiency virus (HIV)-1 RT, clones with turn mutants at rt271-274 of HIV-1 RT were generated and studied by one cycle infection assay. Mutants rtY271A and rtI274A almost lost their replication competency, while mutants rtA272P, rtA272S, and rtG273A retained comparable replication competency relative to wild type pseudotyped HIV-1. To study the mechanisms involved, RT proteins from rt271 to rt274 mutants were expressed and assayed for their RNA dependent DNA polymerase activity, DNA binding activity and processivity. Discordance between RT activity and viral replication efficiency of some turn mutants was observed, indicating that aside from RT, other steps in HIV replication could be affected by substitutions at the turn of helix clamp motif.
authors.affiliation: Laboratory of Medical Molecular Virology, Shanghai Medical College, Fudan University, 138 Yixue Yuan Road, Shanghai 200032, PR China.
authors.forename: Yong-Xiang
authors.initials: YX
authors.lastname: Wang
authors.forename: Hao-Jie
authors.initials: HJ
authors.lastname: Zhang
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Bo-Jian
authors.initials: BJ
authors.lastname: Zheng
authors.forename: Yu-Mei
authors.initials: YM
authors.lastname: Wen
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D019943:Amino Acid Substitution; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D054303:HIV Reverse Transcriptase / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D006801:Humans; D009154:Mutation; D017433:Protein Structure, Secondary; D014779:Virus Replication / Q000235:genetics
chemical_list: D004247:DNA; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase