title: Site-specific inversion sequence of the herpes simplex virus genome: domain and structural features.
abstract: The genome of herpes simplex virus-1 consists of two covalently linked components, L and S, that invert relative to each other. The L and S components consist of unique DNA sequences bracketed by inverted repeats. The inverted repeats of the L component are designated ab and b' a' and those of the S component are designated a' c' and ca. The number of a sequences at the termini and at the L-S component junction varies from one to several copies. Insertion into the middle of the L component of a DNA fragment consisting of 156 base pairs (bp) of the b sequence, an entire a sequence of 501 bp, and 618 bp of the c sequence created a new site through which additional inversions in the genome occurred. Comparison of the nucleotide sequences of DNA fragments containing one and two a sequences defined the domain of the a sequence. The single a sequence consists of two 20-bp direct repeats (designated as DR1) bracketing a region that contains 19 tandem direct repeats of a 12-bp sequence (DR2) adjacent to three direct repeats of a 37-bp sequence (DR4), in addition to short stretches of unique sequences. The fragment with two tandem a sequences contained three copies of DR1-i.e., the intervening DR1 was shared by the two a sequences. Furthermore, one a sequence contained 22 copies of DR2 and two copies of DR4 whereas the second a sequence contained 19 copies of DR2 and two copies of DR4. These observations suggest that (i) amplification of the number of terminal and internal a sequences is the consequence of intramolecular or intermolecular recombination through DR1, (ii) the number of copies of DR2 and DR4 within the a sequence is not fixed and may vary as a consequence of unequal crossing over or slippage, and (iii) inversion results from intramolecular recombination between terminal and inverted a sequences.
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004274:DNA, Recombinant; D004279:DNA, Viral / Q000235:genetics*; D005814:Genes, Viral; D011817:Rabbits; D018139:Simplexvirus / Q000235:genetics*; D012867:Skin; D014162:Transfection
chemical_list: D004274:DNA, Recombinant; D004279:DNA, Viral; D004262:DNA Restriction Enzymes