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M94A3318.TXT
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1994-10-25
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Document 3318
DOCN M94A3318
TI LTR-directed homologous recombination of HIV-1 proviral clone in recA(-)
bacteria.
DT 9412
AU Yamada K; Nakano T; Okamoto T; Dept. Mol. Genetics, Nagoya City Univ.
Med. School, Aichi, Japan.
SO Int Conf AIDS. 1994 Aug 7-12;10(1):103 (abstract no. PA0029). Unique
Identifier : AIDSLINE ICA10/94369257
AB OBJECTIVE: In this study we have attempted to clarify the genetic
mechanism of frequent homologous recombination (HR) during cloning of a
full length HIV-1 plasmid in recA(-) host bacteria. METHODS: A plasmid
containing the full length HIV-1 sequence, pNL432, was transfected into
various recA(-) bacterial strains. The frequency of the appearance of HR
was measured in bacterial colonies when transfected with a closed
circular or linealized plasmid DNA. RESULTS: When pNL432 DNA was
digested at a unique site within the HIV sequence, we frequently
observed generation of mutant truncated clones lacking the entire
proviral sequence except one copy of the LTR (HR). The frequency of HR
was compared with different DNA forms in various recA(-) hosts.
Interestingly, those bacterial strains previously characterized with its
low-rate recombination showed higher rate of HR when the linealized
plasmid was transfected. The nucleotide sequences at the junction point
will be presented at the meeting. DISCUSSION AND CONCLUSIONS: From the
above observations the following possibilities were entertained: (1) HR
might occur due to an unknown mechanism other than the recA system or,
(2) recA(-) phenotype in the tested bacteria might be leaky and it
became detectable by using the linealized plasmid. Therefore, caution
should be taken when plasmid constructions are attempted using a
full-length virus HIV-1 clone. It is noteworthy to consider this
possibility when genetic engineering using a retroviral full length
clone is attempted. Moreover, this system might be useful for the study
of molecular mechanism of HR.
DE Bacteria/GENETICS Cloning, Molecular Genes, Bacterial Genetic
Engineering *HIV Long Terminal Repeat HIV-1/*GENETICS Phenotype
Plasmids/GENETICS Proviruses/*GENETICS *Recombination, Genetic
Transfection MEETING ABSTRACT
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).