Overlapping retrovirus U5 sequence elements are required for efficient integration and initiation of reverse transcription.
A secondary structure in the 5' noncoding region of avian retrovirus RNA, called the U5-leader stem, was shown previously to have a role in initiation of reverse transcription (D. Cobrinik, L. Soskey, and J. Leis, J. Virol. 62:3622-3630, 1988). We now show that an additional RNA secondary structure near the U5 terminus, called the U5-IR stem, is also important for reverse transcription. Mutations that disrupt the U5-IR stem cause a replication defect associated with both a decrease in synthesis of viral DNA in infected cells and a decrease in initiation of reverse transcription in melittin-permeabilized virions. Structure-compensating base substitutions in the U5-IR restore reverse transcription efficiency. In viral DNA, U5-IR sequences are included in the U5 terminal region that functions as a viral integration donor site. When base substitutions are introduced into these sequences, a reduced efficiency of integration in vitro and in vivo is observed. These observations indicate that U5-IR sequences have a structural role in reverse transcription of viral RNA and a sequence-specific role in the integration of viral DNA.
Cobrinik
D
D
Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106.
Aiyar
A
A
Ge
Z
Z
Katzman
M
M
Huang
H
H
Leis
J
J
D001358:Avian Sarcoma Viruses / Q000235:genetics*; D001483:Base Sequence; D002472:Cell Transformation, Viral; D004252:DNA Mutational Analysis; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000235:genetics*; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*; D011995:Recombination, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D013329:Structure-Activity Relationship; D014779:Virus Replication
D009841:Oligonucleotides; D012367:RNA, Viral; D012194:RNA-Directed DNA Polymerase