Participation of the bacteriophage Mu A protein and host factors in the initiation of Mu DNA synthesis in vitro.

Kruklitis, Robert; Nakai, Hiroshi

doi:10.1016/s0021-9258(17)34030-9

Cited by 29 publications

(17 citation statements)

References 63 publications

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“…reconstituted on STC2 with MRFa2A factors (MRFa-DF and MRFa-PR) was strictly dependent on replication proteins of the 13-protein system as previously observed (Kruklitis and Nakai, 1994;Jones and Nakai, 1997). For example, no cointegrates were formed in the absence of the 13-protein system (Table 1) or when PriA, PriB and PriC, DnaT, or DnaBC was omitted from the reaction system (Fig.…”

Section: Resolution Of Mrf a 2a And Its Separation Into Two Component...supporting

confidence: 73%

“…6A). The transpososome of STC1 and STC2 inhibits extension of the leading strand by DNA pol I (Kruklitis and Nakai, 1994; Kruklitis et al ., 1996; Jones et al ., 1998). However, no MuA is associated with STC‐DF, suggesting that MRFα‐DF disassembles the STC2 transpososome and assembles a new nucleoprotein complex in its place.…”

Section: Resultsmentioning

confidence: 99%

“…Bacteriophage Mu, which replicates by transposition (Chaconas and Harshey, 2002), exploits the host restart machinery to initiate DNA synthesis (Nakai et al ., 2001). The phage-encoded MuA transposase not only catalyses strand exchange that creates a forked DNA template where the restart primosome will be assembled (Jones and Nakai, 1997) but also plays an important role in restricting what proteins can assemble at this fork (Kruklitis and Nakai, 1994;1995). MuA transposase and a second transposition protein MuB direct the transfer of Mu ends to target DNA to promote strand exchange.…”

Section: Introductionmentioning

confidence: 99%

“…The transition from transpososome to replisome involves progressive changes in the nucleoprotein complex assembled at the Mu fork, an orderly transition that promotes initiation of Mu DNA replication by the DNA polymerase (pol) III holoenzyme and the major replicative helicase DnaB while protecting the fork from action by other enzymes (Kruklitis and Nakai, 1994;1995). These factors were originally characterized as a partially purified host enzyme fraction (Mu replication factors or MRF) (Kruklitis and Nakai, 1994), which has turned out to be composed of multiple components. The MRF a group of factors disassembles the transpososome and assembles a new nucleoprotein complex (prereplisome) that facilitates replisome assembly (Nakai and Kruklitis, 1995).…”

Section: Introductionmentioning

confidence: 99%

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Host factors that promote transpososome disassembly and the PriA‐PriC pathway for restart primosome assembly

North

Nakai

2005

Molecular Microbiology

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SummaryInitiation of bacteriophage Mu DNA replication by transposition requires the disassembly of the transpososome that catalyses strand exchange and the assembly of a replisome promoted by PriA, PriB, PriC and DnaT proteins, which function in the host to restart stalled replication forks. Once the molecular chaperone ClpX weakens the very tight binding of the transpososome to the Mu ends, host disassembly factors (MRF a a a a -DF) promote the dissociation of the transpososome from the DNA template and the assembly of a new nucleoprotein complex. Prereplisome factors (MRF a a a a -PR) further alter the complex, allowing PriA binding and loading of major replicative helicase DnaB onto the template promoted by the restart proteins. MRF a a a a -PR is essential for DnaB loading by restart proteins even on the deproteinized Mu fork whereas MRF a a a a -DF is not required on the deproteinized template. When the transition from transpososome to replisome was reconstituted using MRF a a a a -DF and MRF a a a a -PR, initiation of Mu DNA replication was strictly dependent upon added PriC and PriA helicase. In contrast, initiation on the deproteinized template was predominantly dependent upon PriB and did not require PriA's helicase activity. The results indicate that transition mechanisms beginning with the transpososome disassembly can determine the pathway of replisome assembly by restart proteins.

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Section: Resolution Of Mrf a 2a And Its Separation Into Two Component...supporting

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Host factors that promote transpososome disassembly and the PriA‐PriC pathway for restart primosome assembly

North

Nakai

2005

Molecular Microbiology

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“…Early studies on Mu B suggested that the C‐terminal domain might interact with replication proteins since removal of the last 13 amino acids resulted in a specific block to replicative transposition, but not to integration of infecting DNA (Chaconas et al ., 1985a). More recently, however, in vitro replication studies have shown that Mu B must be removed before a replication complex can be assembled on the strand transferred product (Kruklitis and Nakai, 1994; Jones and Nakai, 1997, 1999). Unless there are major differences in the in vivo versus the in vitro replication pathways, it seems unlikely that Mu B plays a direct role in the association with replication proteins.…”

Section: Discussionmentioning

confidence: 99%

The solution structure of the C-terminal domain of the Mu B transposition protein

2000

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Mu B is one of four proteins required for the strand transfer step of bacteriophage Mu DNA transposition and the only one where no high resolution structural data is available. Structural work on Mu B has been hampered primarily by solubility problems and its tendency to aggregate. We have overcome this problem by determination of the three-dimensional structure of the C-terminal domain of Mu B (B 223±312 ) in 1.5 M NaCl using NMR spectroscopic methods. The structure of Mu B 223±312 comprises four helices (backbone r.m.s.d. 0.46 A Ê ) arranged in a loosely packed bundle and resembles that of the N-terminal region of the replication helicase, DnaB. This structural motif is likely to be involved in the inter-domainal regulation of ATPase activity for both Mu A and DnaB. The approach described here for structural determination in high salt may be generally applicable for proteins that do not crystallize and that are plagued by solubility problems at low ionic strength.

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ClpX protein of Escherichia coli activates bacteriophage Mu transposase in the strand transfer complex for initiation of Mu DNA synthesis.

1996

Self Cite

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During transposition bacteriophage Mu transposase (MuA) catalyzes the transfer of a DNA strand at each Mu end to target DNA and then remains tightly bound to the Mu ends. Initiation of Mu DNA replication on the resulting strand transfer complex (STC1) requires specific host replication proteins and host factors from two partially purified enzyme fractions designated Mu replication factors alpha and beta (MRFalpha and beta). Escherichia coli ClpX protein, a molecular chaperone, is a component required for MRFalpha activity, which removes MuA from DNA for the establishment of a Mu replication fork. ClpX protein alters the conformation of DNA‐bound MuA and converts STC1 to a less stable form (STC2). One or more additional components of MRFalpha (MRFalpha2) displace MuA from STC2 to form a nucleoprotein complex (STC3), that requires the specific replication proteins and MRFbeta for Mu DNA synthesis. MuA present in STC2 is essential for its conversion to STC3. If MuA is removed from STC2, Mu DNA synthesis no longer requires MRFalpha2, MRFbeta and the specific replication proteins. These results indicate that ClpX protein activates MuA in STC1 so that it can recruit crucial host factors needed to initiate Mu DNA synthesis by specific replication enzymes.

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Participation of the bacteriophage Mu A protein and host factors in the initiation of Mu DNA synthesis in vitro.

Cited by 29 publications

References 63 publications

Host factors that promote transpososome disassembly and the PriA‐PriC pathway for restart primosome assembly

Host factors that promote transpososome disassembly and the PriA‐PriC pathway for restart primosome assembly

The solution structure of the C-terminal domain of the Mu B transposition protein

ClpX protein of Escherichia coli activates bacteriophage Mu transposase in the strand transfer complex for initiation of Mu DNA synthesis.

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