Biomaterial Database

Analysis of plus-strand primer selection, removal, and reutilization by retroviral reverse transcriptases. 2000

S J Schultz, and M Zhang, and C D Kelleher, and J J Champoux

Department of Microbiology, School of Medicine, University of Washington, Seattle, Washington 98195-7242, USA.

The ability of reverse transcriptase to generate, extend, and remove the primer derived from the polypurine tract (PPT) is vital for reverse transcription, since this process determines one of the ends required for integration of the viral DNA. Based on the ability of the RNase H activity of Moloney murine leukemia virus reverse transcriptase to cleave a long RNA/DNA hybrid containing the PPT, it appears that cleavages that could generate the plus-strand primer can occur by an internal cleavage mechanism without any positioning by an RNA 5'-end, and such cleavages may serve to minimize cleavage events within the PPT itself. If the PPT were to be cleaved inappropriately just upstream of the normal plus-strand origin site, the resulting 3'-ends would not be extended by reverse transcriptase. Extension of the PPT primer by at least 2 nucleotides is sufficient for recognition and correct cleavage by RNase H at the RNA-DNA junction to remove the primer. Specific removal of the PPT primer after polymerase extension deviates from the general observation that primer removal occurs by cleavage one nucleotide away from the RNA-DNA junction and suggests that the same PPT specificity determinants responsible for generation of the PPT primer also direct PPT primer removal. Once the PPT primer has been extended and removed from the nascent plus-strand DNA, reinitiation at the resulting plus-strand primer terminus does not occur, providing a mechanism to prevent the repeated initiation of plus strands.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D008979	Moloney murine leukemia virus	A strain of Murine leukemia virus (LEUKEMIA VIRUS, MURINE) arising during the propagation of S37 mouse sarcoma, and causing lymphoid leukemia in mice. It also infects rats and newborn hamsters. It is apparently transmitted to embryos in utero and to newborns through mother's milk.	Moloney Leukemia Virus,Leukemia Virus, Moloney,Virus, Moloney Leukemia
D009692	Nucleic Acid Heteroduplexes	Double-stranded nucleic acid molecules (DNA-DNA or DNA-RNA) which contain regions of nucleotide mismatches (non-complementary). In vivo, these heteroduplexes can result from mutation or genetic recombination; in vitro, they are formed by nucleic acid hybridization. Electron microscopic analysis of the resulting heteroduplexes facilitates the mapping of regions of base sequence homology of nucleic acids.	Heteroduplexes, Nucleic Acid,Heteroduplex DNA,Acid Heteroduplexes, Nucleic,DNA, Heteroduplex
D009843	Oligoribonucleotides	A group of ribonucleotides (up to 12) in which the phosphate residues of each ribonucleotide act as bridges in forming diester linkages between the ribose moieties.
D011994	Recombinant Proteins	Proteins prepared by recombinant DNA technology.	Biosynthetic Protein,Biosynthetic Proteins,DNA Recombinant Proteins,Recombinant Protein,Proteins, Biosynthetic,Proteins, Recombinant DNA,DNA Proteins, Recombinant,Protein, Biosynthetic,Protein, Recombinant,Proteins, DNA Recombinant,Proteins, Recombinant,Recombinant DNA Proteins,Recombinant Proteins, DNA
D004247	DNA	A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).	DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D004591	Electrophoresis, Polyacrylamide Gel	Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.	Polyacrylamide Gel Electrophoresis,SDS-PAGE,Sodium Dodecyl Sulfate-PAGE,Gel Electrophoresis, Polyacrylamide,SDS PAGE,Sodium Dodecyl Sulfate PAGE,Sodium Dodecyl Sulfate-PAGEs
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D012194	RNA-Directed DNA Polymerase	An enzyme that synthesizes DNA on an RNA template. It is encoded by the pol gene of retroviruses and by certain retrovirus-like elements. EC 2.7.7.49.	DNA Polymerase, RNA-Directed,RNA-Dependent DNA Polymerase,Reverse Transcriptase,RNA Transcriptase,Revertase,DNA Polymerase, RNA Directed,DNA Polymerase, RNA-Dependent,RNA Dependent DNA Polymerase,RNA Directed DNA Polymerase
D012313	RNA	A polynucleotide consisting essentially of chains with a repeating backbone of phosphate and ribose units to which nitrogenous bases are attached. RNA is unique among biological macromolecules in that it can encode genetic information, serve as an abundant structural component of cells, and also possesses catalytic activity. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)	RNA, Non-Polyadenylated,Ribonucleic Acid,Gene Products, RNA,Non-Polyadenylated RNA,Acid, Ribonucleic,Non Polyadenylated RNA,RNA Gene Products,RNA, Non Polyadenylated