Tubulin homolog TubZ in a phage-encoded partition system

Oliva, M.A.; Martín-Galiano, Antonio J.; Sakaguchi, Yoshihiko; Andreu, José Manuel

doi:10.1073/pnas.1121546109

Cited by 56 publications

(91 citation statements)

References 31 publications

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“…Although different TubZRC systems have so far been observed to have considerable similarity (25,26), our Bt and Bm TubR complexes exhibit different curvatures. Bt TubRC crystallized as an extended DNA-protein filament with protein wrapping helically around the outside of the DNA, whereas the Bm TubR-DNA complex appears to form a ring or short helix with external DNA.…”

Section: Discussionmentioning

confidence: 98%

“…To confirm that the TubRC complex we had discovered was relevant to the activity of the TubZRC plasmid partitioning system, we assayed its effect on TubZ polymerization by 90°light scattering. A recent study by Oliva and colleagues (25) has shown that TubRC increases polymerization of TubZ. We therefore mixed Bt TubZ with GTP below the critical point of filament formation measurable by light scattering.…”

Section: Resultsmentioning

confidence: 99%

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Superstructure of the centromeric complex of TubZR C plasmid partitioning systems

Aylett

Löwe

2012

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

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Bacterial plasmid partitioning systems segregate plasmids into each daughter cell. In the well-understood ParMRC plasmid partitioning system, adapter protein ParR binds to centromere parC, forming a helix around which the DNA is externally wrapped. This complex stabilizes the growth of a filament of actin-like ParM protein, which pushes the plasmids to the poles. The TubZRC plasmid partitioning system consists of two proteins, tubulin-like TubZ and TubR, and a DNA centromere, tubC, which perform analogous roles to those in ParMRC, despite being unrelated in sequence and structure. We have dissected in detail the binding sites that comprise Bacillus thuringiensis tubC, visualized the TubRC complex by electron microscopy, and determined a crystal structure of TubR bound to the tubC repeat. We show that the TubRC complex takes the form of a flexible DNA-protein filament, formed by lateral coating along the plasmid from tubC, the full length of which is required for the successful in vitro stabilization of TubZ filaments. We also show that TubR from Bacillus megaterium forms a helical superstructure resembling that of ParR. We suggest that the TubRC DNA-protein filament may bind to, and stabilize, the TubZ filament by forming such a ring-like structure around it. The helical superstructure of this TubRC may indicate convergent evolution between the actincontaining ParMRC and tubulin-containing TubZRC systems.FtsZ | X-ray crystallography | DNA segregation L ow copy number plasmids often encode their own segregation machinery, ensuring that copies are partitioned into each daughter cell. These plasmid-partitioning systems organize replicated plasmids and actively separate them. The known plasmidpartitioning systems are minimalist and elegant. They consist of just three components: a DNA centromere, an adapter protein that binds the centromere, forming the centromeric complex, and a nucleotide triphosphate-dependent filament-forming protein, which produces the force to move the plasmids (1, 2).Plasmid partitioning systems have been divided into types I-III, based upon the homology of their filament-forming proteins to known protein families (2, 3). Type I plasmid partitioning systems (4, 5) are based on deviant Walker A ATPases (6, 7), type II (8) on actin-like proteins (9), and type III (10-12) on tubulin/FtsZ-like proteins (13,14). Although the structure of the filament implicated in segregation has been determined for all three systems (9, 14-16), only examples of type I and II centromeric complexes have so far been resolved (17)(18)(19).The centromeric complex of the type II (actin-like) ParMRC plasmid partitioning system is formed by the binding of adapter protein ParR to parC, a series of parallel (direct), 11-base pair (bp) repeats (20). The superstructure this complex forms is helical, right-handed, and places the parC DNA on the exterior of the helix and ParR on the interior (18,19). This arrangement clusters the interaction surfaces between ParM and ParR, which are located at the tip of the ParM filament and ...

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Section: Discussionmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Superstructure of the centromeric complex of TubZR C plasmid partitioning systems

Aylett

Löwe

2012

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

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“…Additional components similar to organizing centers, spindle poles that anchor filaments as suggested for the PhuZ-based phage centering system (28), or other regulators may be required (29). One possibility for an anchor could be the nucleoid, and it has been noted that another gene, downstream of TubZRC, tubY (pBt158 on pBtoxis), might have DNA-binding activity and hence might be a candidate for this requirement (20). Alternately, at high intracellular TubZ concentrations, net growth could prevail, meaning a pushing mechanism is possible in principle.…”

Section: Discussionmentioning

confidence: 99%

“…Binding of both truncated (iterons 1-3) and full-length (iterons 1-7) TubRC allowed for slow depolymerization and did not inhibit treadmilling. This effect explained the previously suggested stabilization effect of TubRC on filament formation (17,20). To check that the measured reduction in shrinkage was not caused by TubZ filament growth facilitated by bound TubRC, filaments were sequentially grown using differently labeled TubZ monomers, whereas TubR and tubC concentrations were kept constant.…”

Section: Tubrc Does Not Induce Insertional Polymerizationmentioning

confidence: 99%

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Reconstitution of a prokaryotic minus end-tracking system using TubRC centromeric complexes and tubulin-like protein TubZ filaments

Fink

Löwe

2015

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

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Segregation of DNA is a fundamental process during cell division. The mechanism of prokaryotic DNA segregation is largely unknown, but several low-copy-number plasmids encode cytomotive filament systems of the actin type and tubulin type important for plasmid inheritance. Of these cytomotive filaments, only actin-like systems are mechanistically well characterized. In contrast, the mechanism by which filaments of tubulin-like TubZ protein mediate DNA motility is unknown. To understand polymer-driven DNA transport, we reconstituted the filaments of TubZ protein (TubZ filaments) from Bacillus thuringiensis pBtoxis plasmid with their centromeric TubRC complexes containing adaptor protein TubR and tubC DNA. TubZ alone assembled into polar filaments, which annealed laterally and treadmilled. Using single-molecule imaging, we show that TubRC complexes were not pushed by filament polymerization; instead, they processively tracked shrinking, depolymerizing minus ends. Additionally, the TubRC complex nucleated TubZ filaments and allowed for treadmilling. Overall, our results indicate a pulling mechanism for DNA transport by the TubZRC system. The discovered minus end-tracking property of the TubRC complex expands the mechanistic diversity of the prokaryotic cytoskeleton.cytoskeleton | tubulin homologue | DNA segregation

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Tubulin and FtsZ Superfamily of Protein Assembly Machines

Oliva

Andreu

2014

Encyclopedia of Life Sciences

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Eukaryotic αβ‐tubulin and bacterial FtsZ self‐assemble into dynamic cytoskeletal polymers, microtubules or filaments, which are essential for chromosome segregation or bacterial cell division, respectively. Both share homologous core structures with guanosine‐5'‐triphosphate (GTP) ‐binding and GTPase‐activating domains joined by a central helix, and form similar protofilaments with 4 nm spaced subunits along them. During assembly, the GTPase‐activating domain of one subunit associates with the GTP binding domain of the preceding subunit, completing the active site. GTP hydrolysis triggers disassembly, which is coupled to free subunits switching into inactive conformation. Microtubule dynamics is inhibited by anticancer drugs binding near tubulin assembly interfaces. FtsZ is a target for new antibiotics discovery; several bacterial division inhibitors bind between FtsZ domains or at its GTP site. Other proteins in this superfamily include: gamma‐tubulin that is essential for microtubule organisation; bacterial tubulin, a primitive structural homologue; and recently discovered TubZ, distant homologue employed by plasmids and phages for deoxyribonucleic acid positioning. Key Concepts: Tubulin superfamily proteins share a common fold within two domains that is different from other GTPases. They assemble into microtubules and other different types of dynamic cytoskeletal filaments. GTP hydrolysis is activated upon assembly and triggers disassembly. Tubulin homologues spread among most organisms, where they are central to essential functions including DNA segregation or cell division. They have important biomedical implications. Several effective antitumor drugs work by impairing microtubule dynamics. FtsZ is a target for new antibiotics.

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Tubulin homolog TubZ in a phage-encoded partition system

Cited by 56 publications

References 31 publications

Superstructure of the centromeric complex of TubZR C plasmid partitioning systems

Superstructure of the centromeric complex of TubZR C plasmid partitioning systems

Reconstitution of a prokaryotic minus end-tracking system using TubRC centromeric complexes and tubulin-like protein TubZ filaments

Tubulin and FtsZ Superfamily of Protein Assembly Machines

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