Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sequence organization and origin of HSV-1 strain Angelotti (ANG) class II defective DNA (HSV-1 ANG dDNA1) were examined in detail by establishing physical maps and by molecular cloning. dDNA1 consists of concatemers of tandem repeat units in which sequences from the UL region spanning map coordinates 0.37 to 0.415 of standard HSV ANG DNA are covalently linked to TRS/IRS sequences. The size of the repeat unit was determined to be about 8.9 kilobase pairs (kb), comprising sequences of 7.3 kb from UL and 1.6 kb from TRS/IRS regions. UL sequences were delineated by restriction enzyme sites KpnI N-P and EcoRI F-M, and were colinear with the corresponding sequences of the standard (wild-type) virus genome. Expression of dDNA1 was studied in African green monkey kidney cells and in Xenopus laevis oocytes. A major polypeptide of approx. mol. wt. 135 000 (135K) was overproduced, suggesting that this protein was encoded by dDNA1. By several parameters, e.g. size, immune cross-reactivity, and affinity for native and denatured DNA, the 135K polypeptide was identified as the major HSV DNA-binding protein. It was further shown that the repeat unit contains part of the DNA polymerase gene as demonstrated by its ability to rescue some mutations in this gene.
 ...
PMID:Herpes simplex virus defective genomes: structure of HSV-1 ANG defective DNA of class II and encoded polypeptides. 631 66

The influence of mutations in the 3' to 5' exonucleolytic proofreading epsilon-subunit of Escherichia coli DNA polymerase III on the genetic instabilities of the CGG.CCG and the CTG.CAG repeats that cause human hereditary neurological diseases was investigated. The dnaQ49(ts) and the mutD5 mutations destabilize the CGG.CCG repeats. The distributions of the deletion products indicate that slipped structures containing a small number of repeats in the loop mediate the deletion process. The CTG.CAG repeats were destabilized by the dnaQ49(ts) mutation by a process mediated by long hairpin loop structures (>/=5 repeats). The mutD5 mutator strain stabilized the (CTG.CAG)(175) tract, which contained two interruptions. Since the mutD5 mutator strain has a saturated mismatch repair system, the stabilization is probably an indirect effect of the nonfunctional mismatch repair system in these strains. Shorter uninterrupted tracts expand readily in the mutD5 strain, presumably due to the greater stability of long CTG.CAG tracts (>100 repeats) in this strain. When parallel studies were conducted in minimal medium, where the mutD5 strain is defective in exonucleolytic proofreading but has a functional MMR system, both CTG.CAG and CGG.CCG repeats were destabilized, showing that the proofreading activity is essential for maintaining the integrity of TRS tracts. Thus, we conclude that the expansion and deletion of triplet repeats are enhanced by mutations that reduce the fidelity of replication.
 ...
PMID:DNA polymerase III proofreading mutants enhance the expansion and deletion of triplet repeat sequences in Escherichia coli. 1063 23