title: Inhibition of reverse transcription in vivo by elevated manganese ion concentration.
abstract: Mutations in PMR1, a yeast gene encoding a calcium/manganese exporter, dramatically decrease Ty1 retrotransposition. Ty1 cDNA is reduced in pmr1 mutant cells, despite normal levels of Ty1 RNA and proteins. The transposition defect results from Mn(2+) accumulation that inhibits reverse transcription. Cytoplasmic accumulation of Mn(2+) in pmr1 cells may directly affect reverse transcriptase (RT) activity. Trace amounts of Mn(2+) potently inhibit Ty1 RT and HIV-1 RT in vitro when the preferred cation, Mg(2+), is present. Both Mn(2+) and Mg(2+) alone activate Ty1 RT cooperatively with Hill coefficients of 2, providing kinetic evidence for a dual divalent cation requirement at the RT active site. We propose that occupancy of the B site is the major determinant of catalytic activity and that Mn(2+) at this site greatly reduces catalytic activity.
authors: Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
authors: Eric C
authors: EC
authors: Bolton
authors: Albert S
authors: AS
authors: Mildvan
authors: Jef D
authors: JD
authors: Boeke
mesh_terms: D001665:Binding Sites; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D020134:Catalytic Domain; D002412:Cations / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D054303:HIV Reverse Transcriptase / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D015497:HIV-1 / Q000187:drug effects / Q000201:enzymology; D017136:Ion Transport; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D012194:RNA-Directed DNA Polymerase / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D018626:Retroelements / Q000187:drug effects*; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D002412:Cations; D018076:DNA, Complementary; D018832:Molecular Chaperones; D011993:Recombinant Fusion Proteins; D018626:Retroelements; D018894:Reverse Transcriptase Inhibitors; C101767:SSC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D008345:Manganese; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase; D000252:Calcium-Transporting ATPases; D008274:Magnesium