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

Bacteriophage Mu replicates as a transposable element, exploiting host enzymes to promote initiation of DNA synthesis. The phage-encoded transposase MuA, assembled into an oligomeric transpososome, promotes transfer of Mu ends to target DNA, creating a fork at each end, and then remains tightly bound to both forks. In the transition to DNA synthesis, the molecular chaperone ClpX acts first to weaken the transpososome's interaction with DNA, apparently activating its function as a molecular matchmaker. This activated transpososome promotes formation of a new nucleoprotein complex (prereplisome) by yet unidentified host factors [Mu replication factors (MRF alpha 2)], which displace the transpososome in an ATP-dependent reaction. Primosome assembly proteins PriA, PriB, DnaT, and the DnaB--DnaC complex then promote the binding of the replicative helicase DnaB on the lagging strand template of the Mu fork. PriA helicase plays an important role in opening the DNA duplex for DnaB binding, which leads to assembly of DNA polymerase III holoenzyme to form the replisome. The MRF alpha 2 transition factors, assembled into a prereplisome, not only protect the fork from action by nonspecific host enzymes but also appear to aid in replisome assembly by helping to activate PriA's helicase activity. They consist of at least two separable components, one heat stable and the other heat labile. Although the MRF alpha 2 components are apparently not encoded by currently known homologous recombination genes such as recA, recF, recO, and recR, they may fulfill an important function in assembling replisomes on arrested replication forks and products of homologous strand exchange.
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PMID:Handoff from recombinase to replisome: insights from transposition. 1145 60

The Escherichia coli UmuD' protein is a component of DNA polymerase V, an error-prone polymerase that carries out translesion synthesis on damaged DNA templates. The intracellular concentration of UmuD' is strictly controlled by regulated transcription, by posttranslational processing of UmuD to UmuD', and by ClpXP degradation. UmuD' is a substrate for the ClpXP protease but must form a heterodimer with its unabbreviated precursor, UmuD, for efficient degradation to occur. Here, we show that UmuD functions as a UmuD' delivery protein for ClpXP. UmuD can also deliver a UmuD partner for degradation. UmuD resembles SspB, a well-characterized substrate-delivery protein for ClpX, in that both proteins use related peptide motifs to bind to the N-terminal domain of ClpX, thereby tethering substrate complexes to ClpXP. The combined use of a weak substrate recognition signal and a delivery factor that tethers the substrate to the protease allows regulated proteolysis of UmuD/D' in the cell. Dual recognition strategies of this type may be a relatively common feature of intracellular protein turnover.
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PMID:Distinct peptide signals in the UmuD and UmuD' subunits of UmuD/D' mediate tethering and substrate processing by the ClpXP protease. 1459 14