Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.5.1.2 (DNA ligase)
 2,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The genome of the nondefective parvovirus minute virus of mice (MVM) is a linear DNA molecular weight 1.48 x 10(6), which is single stranded for approximately 94% of its length. In contrast to the genomes from defective parvoviruses MVM DNA does not contain a detectable inverted terminal redundancy. A combination of enzymatic and physical techniques has shown that the molecule contains a stable hairpin duplex of approximately 130 base pairs located at the 5' terminus of the genome. MVM DNA is efficiently utilized as a template-primer by a number of DNA polymerases, including reverse transcriptases. Polymerases lacking 5' to 3' exonuclease activity yield a duplex DNA product with a molecular weight 1.96 times that of the viral genome, in which the newly synthesized complementary strand is covalently attached to the template. This duplex contains an internal "nick" that can be sealed by DNA ligase to produce a self-complementary single-strand circle. The MVM DNA duplex is cleaved twice by EcoR-RI restriction endonuclease to yield three distinct fragments in molar amounts. These results suggest that the initiation of DNA synthesis in vitro occurs at a point within 100 bases of the 3' end of the genome, using the 3' terminus of viral DNA as a primer, and that the sequence of nucleotides in the genome is not permuted.
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PMID:DNA of minute virus of mice: self-priming, nonpermuted, single-stranded genome with a 5'-terminal hairpin duplex. 78 12

DNA polymerase alpha was studied in a direct gap-filling assay. Using a defined template, DNA synthesis was primed from the M13 17-mer universal primer and blocked by an oligonucleotide hybridized 56 nucleotides downstream of the primer. DNA polymerase alpha filled this gap to completion. A time course of the reaction showed that in 50% of the substrate molecules, gaps were filled to completion within 10 min. In another 35% of the molecules the final nucleotide was lacking after 10 min. This nucleotide was added at a reduced rate, and was not incorporated into all of the molecules even after 6 h. The reduced rate of incorporation of the final nucleotide is reflected in an increased Km for de novo incorporation of one nucleotide at a single nucleotide gap (0.7 microM), as opposed to the Km for de novo incorporation of one nucleotide into singly primed M13 DNA (0.18 microM). DNA polymerase alpha purified from murine cells infected with the parvovirus minute virus of mice, and HeLa cell DNA polymerase alpha 2, exhibited the same kinetics of gap filling as did DNA polymerase alpha purified from uninfected Ehrlich ascites murine tumor cells. T4 DNA polymerase filled gaps to completion in this assay. Escherichia coli DNA polymerase I Klenow fragment quantitatively displaced the downstream oligonucleotide, and extended nascent DNA chains for an additional 100 nucleotides. Nicks and single-nucleotide gaps produced in gap-filling reactions by murine DNA polymerase alpha and T4 DNA polymerase were sealed by T4 DNA ligase.
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PMID:Murine DNA polymerase alpha fills gaps to completion in a direct assay. Altered kinetics of de novo DNA synthesis at single nucleotide gaps. 240 70