The AAA+ ClpX machine unfolds a keystone subunit to remodel the Mu transpososome

Abdelhakim, Aliaa H.; Sauer, Robert T.; Baker, Tania A.

doi:10.1073/pnas.0910905106

Cited by 21 publications

(22 citation statements)

References 32 publications

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“…On transpososomes assembled in vitro , the chaperone activity of ClpX selectively unfolds one or the other of the catalytic subunits so as to destabilize (but not destroy) the entire complex (Fig. 9A) (109–111). Interestingly, MuA residues exposed only in the MuA tetramer are important for enhanced recognition by ClpX, ensuring that the tetrameric complex is a high-priority substrate (111, 112).…”

Section: Transition From Transposition To Replicationmentioning

confidence: 99%

Transposable Phage Mu

Harshey

2014

Microbiol Spectr

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Transposable phage Mu has played a major role in elucidating the mechanism of movement of mobile DNA elements. The high efficiency of Mu transposition has facilitated a detailed biochemical dissection of the reaction mechanism, as well as of protein and DNA elements that regulate transpososome assembly and function. The deduced phosphotransfer mechanism involves in-line orientation of metal ion-activated hydroxyl groups for nucleophilic attack on reactive diester bonds, a mechanism that appears to be used by all transposable elements examined to date. A crystal structure of the Mu transpososome is available. Mu differs from all other transposable elements in encoding unique adaptations that promote its viral lifestyle. These adaptations include multiple DNA (enhancer, SGS) and protein (MuB, HU, IHF) elements that enable efficient Mu end synapsis, efficient target capture, low target specificity, immunity to transposition near or into itself, and efficient mechanisms for recruiting host repair and replication machineries to resolve transposition intermediates. MuB has multiple functions, including target capture and immunity. The SGS element promotes gyrase-mediated Mu end synapsis, and the enhancer, aided by HU and IHF, participates in directing a unique topological architecture of the Mu synapse. The function of these DNA and protein elements is important during both lysogenic and lytic phases. Enhancer properties have been exploited in the design of mini-Mu vectors for genetic engineering. Mu ends assembled into active transpososomes have been delivered directly into bacterial, yeast, and human genomes, where they integrate efficiently, and may prove useful for gene therapy.

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Section: Transition From Transposition To Replicationmentioning

confidence: 99%

Transposable Phage Mu

Harshey

2014

Microbiol Spectr

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“…ClpX interacts with the C-terminus of MuA in a strand-transfer transpososome (i.e. the MuA complex in which the Mu ends are joined to the target), and remodels it in preparation for replication (Kruklitis et al , 1996, Levchenko et al , 1997, Nakai et al , 2001, Abdelhakim et al , 2010). The shortened FD is eventually repaired, resulting in a simple Mu insertion (Fig.…”

Section: Introductionmentioning

confidence: 99%

Controlling DNA degradation from a distance: a new role for the Mu transposition enhancer

Choi

Saha

Jang

et al. 2014

Molecular Microbiology

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Summary Phage Mu is unique among transposable elements in employing a transposition enhancer. The enhancer DNA segment is the site where the transposase MuA binds and makes bridging interactions with the two Mu ends, interwrapping the ends with the enhancer in a complex topology essential for assembling a catalytically active transpososome. The enhancer is also the site at which regulatory proteins control divergent transcription of genes that determine the phage lysis-lysogeny decision. Here we report a third function for the enhancer - that of regulating degradation of extraneous DNA attached to both ends of infecting Mu. This DNA is protected from nucleases by a phage protein until Mu integrates into the host chromosome, after which it is rapidly degraded. We find that leftward transcription at the enhancer, expected to disrupt its topology within the transpososome, blocks degradation of this DNA. Disruption of the enhancer would lead to the loss or dislocation of two non-catalytic MuA subunits positioned in the transpososome by the enhancer. We provide several lines of support for this inference, and conclude that these subunits are important for activating degradation of the flanking DNA. This work also reveals a role for enhancer topology in phage development.

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“…This is accomplished by a host-encoded remodeling protein, ClpX, which is a member of the Clp/Hsp100 family of AAA+ ATPases (20,177). ClpX recognizes a specific sequence at the C-terminus of MuA, and unfolds one particular subunit of the tetramer in an ATP-dependent reaction; this appears to destabilize the transpososome enough to allow functional replication forks to be assembled (178)(179)(180).…”

Section: Genome Repair After Transposon Insertionmentioning

confidence: 99%

Mechanisms of DNA Transposition

Hickman

Dyda

2015

Microbiol Spectr

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DNA transposases use a limited repertoire of structurally and mechanistically distinct nuclease domains to catalyze the DNA strand breaking and rejoining reactions that comprise DNA transposition. Here, we review the mechanisms of the four known types of transposition reactions catalyzed by (1) RNase H-like transposases (also known as DD(E/D) enzymes); (2) HUH single-stranded DNA transposases; (3) serine transposases; and (4) tyrosine transposases. The large body of accumulated biochemical and structural data, particularly for the RNase H-like transposases, has revealed not only the distinguishing features of each transposon family, but also some emerging themes that appear conserved across all families. The more-recently characterized single-stranded DNA transposases provide insight into how an ancient HUH domain fold has been adapted for transposition to accomplish excision and then site-specific integration. The serine and tyrosine transposases are structurally and mechanistically related to their cousins, the serine and tyrosine site-specific recombinases, but have to date been less intensively studied. These types of enzymes are particularly intriguing as in the context of site-specific recombination they require strict homology between recombining sites, yet for transposition can catalyze the joining of transposon ends to form an excised circle and then integration into a genomic site with much relaxed sequence specificity.In this chapter, we provide an overview of the fundamental concepts of DNA transposition mechanisms. Our aim is to emphasize basic themes and, in this effort, we will focus on specific illustrative cases rather than attempt an exhaustive review of the literature. We hope that the selected references will point the curious reader towards the landmark studies in the field as well as some of the most exciting recent results. We also direct the reader to other recent reviews (1-3).DNA transposases are enyzmes that move discrete segments of DNA called transposons from one location in the genome (often called the donor site) to a new site without using RNA intermediates. DNA transposases are usually encoded by the mobile element itself (in which case they are "autonomous" transposons). However, some transposons are missing a self-encoded transposase yet have ends that can be recognized by a transposase encoded somewhere else in the genome, and thus are "non-autonomous" (Siguier et al., this volume). Although logic suggests that all DNA transposons are moved by transposases, the term was originally reserved for those enzymes that do not require significant regions of homology between any part of the transposon and the sites to which they are moved, the so-called target (or insertion or integration) sites. As biology is not always neat and tidy, transposases can exhibit a spectrum of homology requirements and vagaries of terminology have arisen such that certain transposases are sometimes referred to as "resolvases" or by the generic term "recombinases".From a mechanistic perspective, t...

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The AAA+ ClpX machine unfolds a keystone subunit to remodel the Mu transpososome

Cited by 21 publications

References 32 publications

Transposable Phage Mu

Transposable Phage Mu

Controlling DNA degradation from a distance: a new role for the Mu transposition enhancer

Mechanisms of DNA Transposition

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