Instability of bacteriophage Mu transposase and the role of host Hfl protein

Gama, M.-J.; Toussaint, Ariane; Pato, Martin L.

doi:10.1111/j.1365-2958.1990.tb02038.x

Cited by 9 publications

(6 citation statements)

References 25 publications

(11 reference statements)

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“…It is difficult to tell if MuA is normally degraded by ClpXP. In vivo, both physical and functional assays demonstrate that MuA is unstable Reich 1982, 1984;Gama et al 1990). Mutations in hflA and hflB stabilize MuA (Gama et al 1990), whereas a clpX mutation does not have a substainal effect (Mhammedi-Alaoui et al 1994), indicating that the Hfl proteases, rather than ClpXP, are principally responsible for its degradation.…”

Section: The Clp Protein Family As Chaperones and Mediators Of Proteomentioning

confidence: 99%

“…In vivo, both physical and functional assays demonstrate that MuA is unstable Reich 1982, 1984;Gama et al 1990). Mutations in hflA and hflB stabilize MuA (Gama et al 1990), whereas a clpX mutation does not have a substainal effect (Mhammedi-Alaoui et al 1994), indicating that the Hfl proteases, rather than ClpXP, are principally responsible for its degradation. However, it is possible that the pool of MuA in the STCs is usually degraded by ClpXP; this would explain why MuA is still functionally unstable in hfl defective host cells (Gama et al 1990).…”

Section: The Clp Protein Family As Chaperones and Mediators Of Proteomentioning

confidence: 99%

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Disassembly of the Mu transposase tetramer by the ClpX chaperone.

Levchenko¹,

Luo²,

Baker³

1995

Genes Dev.

266

241

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Mu transposition is promoted by an extremely stable complex containing a tetramer of the transposase (MuA) bound to the recombining DNA. Here we purify the Escherichia coli ClpX protein, a member of a family of multimeric ATPases present in prokaryotes and eukaryotes (the Clp family), on the basis of its ability to remove the transposase from the DNA after recombination. Previously, ClpX has been shown to function with the ClpP peptidase in protein turnover. However, neither ClpP nor any other protease is required for disassembly of the transposase. The released MuA is not modified extensively, degraded, or irreversibly denatured, and is able to perform another round of recombination in vitro. We conclude that ClpX catalyzes the ATP-dependent release of MuA by promoting a transient conformational change in the protein and, therefore, can be considered a molecular chaperone. ClpX is important at the transition between the recombination and DNA replication steps of transposition in vitro; this function probably corresponds to the essential contribution of ClpX for Mu growth. Deletion analysis reveals that the sequence at the carboxyl terminus of MuA is important for disassembly by ClpX and can target MuA for degradation by ClpXP in vitro. These data contribute to the emerging picture that members of the Clp family are chaperones specifically suited for disaggregating proteins and are able to function with or without a collaborating protease.

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Section: The Clp Protein Family As Chaperones and Mediators Of Proteomentioning

confidence: 99%

Section: The Clp Protein Family As Chaperones and Mediators Of Proteomentioning

confidence: 99%

Disassembly of the Mu transposase tetramer by the ClpX chaperone.

Levchenko¹,

Luo²,

Baker³

1995

Genes Dev.

266

241

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“…We found that a loss of ftsH function altered membrane topology of a SecY-PhoA fusion protein and suggested that FtsH might have a chaperone-like activity (13)(14)(15). On the other hand, some unstable proteins have been shown to be stabilized in the ftsH mutants (8,12,(16)(17)(18). In vitro experiments directly showed that FtsH has an ATPdependent proteolytic activity against the 32 protein (12) and the SecY protein (19).…”

mentioning

confidence: 90%

Host regulation of lysogenic decision in bacteriophage λ: Transmembrane modulation of FtsH (HflB), the cII degrading protease, by HflKC (HflA)

Kihara

Akiyama²,

Ito³

1997

Proc. Natl. Acad. Sci. U.S.A.

105

120

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The cII gene product of bacteriophage is unstable and required for the establishment of lysogenization. Its intracellular amount is important for the decision between lytic growth and lysogenization. Two genetic loci of Escherichia coli are crucial for these commitments of infecting genome. One of them, hflA encodes the Hf lKC membrane protein complex, which has been believed to be a protease degrading the cII protein. However, both its absence and overproduction stabilized cII in vivo and the proposed serine protease-like sequence motif in Hf lC was dispensable for the lysogenization control. Moreover, the Hf lKC protein was found to reside on the periplasmic side of the plasma membrane. In contrast, the other host gene, ftsH (hflB) encoding an integral membrane ATPase͞protease, is positively required for degradation of cII, since loss of its function stabilized cII and its overexpression accelerated the cII degradation. In vitro, purified FtsH catalyzed ATP-dependent proteolysis of cII and Hf lKC antagonized the FtsH action. These results, together with our previous finding that FtsH and Hf lKC form a complex, suggest that FtsH is the cII degrading protease and Hf lKC is a modulator of the FtsH function. We propose that this transmembrane modulation differentiates the FtsH actions to different substrate proteins such as the membrane-bound SecY protein and the cytosolic cII protein. This study necessitates a revision of the prevailing view about the host control over lysogenic decision.

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“…Transposase is functionally and physically unstable and hence has to be continuously synthesized (Pato & Reich, 1982). The host Hfl protease is in part responsible for this instability (Gama, Toussaint & Pato, 1990).…”

Section: The Lytic Cyclementioning

confidence: 99%

Regulation of bacteriophage Mu transposition

et al. 1994

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Bacteriophage Mu is a transposon and a temperate phage which has become a paradigm for the study of the molecular mechanism of transposition. As a prophage, Mu has also been used to study some aspects of the influence of the host cell growth phase on the regulation of transposition. Through the years several host proteins have been identified which play a key role in the replication of the Mu genome by successive rounds of replicative transposition as well as in the maintenance of the repressed prophage state. In this review we have attempted to summarize all these findings with the purpose of emphasizing the benefit the virus and the host cell can gain from those phage-host interactions.

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Instability of bacteriophage Mu transposase and the role of host Hfl protein

Cited by 9 publications

References 25 publications

Disassembly of the Mu transposase tetramer by the ClpX chaperone.

Disassembly of the Mu transposase tetramer by the ClpX chaperone.

Host regulation of lysogenic decision in bacteriophage λ: Transmembrane modulation of FtsH (HflB), the cII degrading protease, by HflKC (HflA)

Regulation of bacteriophage Mu transposition

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