Suppression of mutant phenotypes of the Agrobacterium tumefaciens VirB11 ATPase by overproduction of VirB proteins

Zhou, Xue Rong; Christie, Peter J.

doi:10.1128/jb.179.18.5835-5842.1997

Cited by 39 publications

(52 citation statements)

References 58 publications

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“…VirB10 is also dependent on VirB11 ATP utilization for the structural transition, yet so far there is no evidence for complex formation between VirB10 and VirB11. In contrast, a VirD4-VirB11 interaction is supported by genetic suppression (27), TrIP data (3, 7), and results of coimmunoprecipitation studies indicating that VirD4 and VirB11 stably interact independently of other T4SS subunits (7). VirB11 might induce the VirB10 conformational switch indirectly through its interaction with VirD4, although at this time a direct transient or weak affinity contact between VirB11 and VirB10 cannot be excluded.…”

Section: Discussionmentioning

confidence: 95%

Agrobacterium VirB10, an ATP energy sensor required for type IV secretion

Cascales

Christie

2004

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

136

168

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Bacteria use type IV secretion systems (T4SS) to translocate DNA and protein substrates to target cells of phylogenetically diverse taxa. Recently, by use of an assay termed transfer DNA immunoprecipitation (TrIP), we described the translocation route for a DNA substrate [T-DNA, portion of the Ti (tumor-inducing) plasmid that is transferred to plant cells] of the Agrobacterium tumefaciens VirB͞D4 T4SS in terms of a series of temporally and spatially ordered substrate contacts with subunits of the secretion channel. Here, we report that the bitopic inner membrane protein VirB10 undergoes a structural transition in response to ATP utilization by the VirD4 and VirB11 ATP-binding subunits, as monitored by protease susceptibility. VirB10 interacts with inner membrane VirD4 independently of cellular energetic status, whereas the energy-induced conformational change is required for VirB10 complex formation with an outer membrane-associated heterodimer of VirB7 lipoprotein and VirB9, as shown by coimmunoprecipitation. Under these conditions, the T-DNA substrate is delivered from the inner membrane channel components VirB6 and VirB8 to periplasmic and outer membrane-associated VirB2 pilin and VirB9. We propose that VirD4 and VirB11 coordinate the ATP-dependent formation of a VirB10 ''bridge'' between inner and outer membrane subassemblies of the VirB͞D4 T4SS, and that this morphogenetic event is required for T-DNA translocation across the A. tumefaciens cell envelope. conjugation ͉ energy coupling ͉ pathogenesis ͉ membrane complex ͉ translocation

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Section: Discussionmentioning

confidence: 95%

Agrobacterium VirB10, an ATP energy sensor required for type IV secretion

Cascales

Christie

2004

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

136

168

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“…Negative dominant effects of mutants of R388 TrwD (16) and Agrobacterium tumefaciens VirB11 (18,26,27) indicate that these proteins are functioning as multimers and͞or that they are interacting with other components of the secretion machinery. A TrbB mutant in the Walker A box (K161A) also showed a transdominant effect (20).…”

Section: Discussionmentioning

confidence: 99%

Sequence-related protein export NTPases encoded by the conjugative transfer region of RP4 and by the cag pathogenicity island of Helicobacter pylori share similar hexameric ring structures

Krause¹

2000

Proceedings of the National Academy of Sciences

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RP4TrbB, an essential component of the conjugative transfer apparatus of the broad-host-range plasmid RP4, is a member of the PulE protein superfamily involved in multicomponent machineries transporting macromolecules across the bacterial envelope. PulElike proteins share several well conserved motifs, most notable a nucleoside triphosphate binding motif (P-loop). Helicobacter pylori HP0525 also belongs to the PulE superfamily and is encoded by the pathogenicity island cag, involved in the inflammatory response of infected gastric epithelial cells in mammals. The native molecular masses of TrbB and HP0525 as determined by gel filtration and glycerol gradient centrifugation suggested a homohexameric structure in the presence of ATP and Mg 2؉ . In the absence of nucleotides and bivalent cations, TrbB behaved as a tetramer whereas the hexameric state of HP0525 remained unaffected. Electron microscopy and image processing demonstrated that TrbB and HP0525 form ring-shaped complexes (diameter: 12 nm) with a central region (diameter: 3 nm) of low electron density when incubated in the presence of ATP and Mg 2؉ . However, the TrbB average image appeared to be more elliptical with strong twofold rotational symmetry whereas HP0525 complexes are regular hexagons. Six well defined triangle-shaped areas of high electron density were distinguishable in both cases. Covalent crosslinking of TrbB suggests that the hexameric ring is composed from a trimer of dimers, because only dimeric, tetrameric, and hexameric species were detectable. The toroidal structure of TrbB and HP0525 suggests that both proteins catalyze a repetitive process, most probably translocating a cognate substrate across the inner membrane.

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“…However, several amino acid substitutions in the T4SS components VirB6, VirB9, VirB10, and VirB11 have been demonstrated to block the polymerization of VirB2 pilin to form the extracellular T-pilus but do not significantly affect substrate transfer. These "uncoupling" mutations still require intracellular VirB2 for substrate transfer (Zhou and Christie, 1997;Sagulenko et al, 2001;Jakubowski et al, 2003Jakubowski et al, , 2005Jakubowski et al, , 2009Banta et al, 2011;Garza and Christie, 2013). Wu et al (Wu et al, 2014a) further generated several uncoupling virB2 mutants with single amino acid substitutions in the VirB2 protein that retain wild-type levels of tumor formation on tomato stems but show reductions in transient transformation efficiencies of Arabidopsis seedlings.…”

Section: Transport Of T-dna and Virulence Proteins Via Type IV Secretmentioning

confidence: 99%