Analysis of eight out genes in a cluster required for pectic enzyme secretion by Erwinia chrysanthemi: sequence comparison with secretion genes from other gram-negative bacteria

Lindeberg, Magdalen; Collmer, Alan

doi:10.1128/jb.174.22.7385-7397.1992

Cited by 106 publications

(62 citation statements)

References 43 publications

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“…Homologues of XpsD are widespread in Gram-negative bacteria. Among them, the PulD protein of Klebsiella oxytoca (8), the OutD protein of Erwinia chrysanthemi (9,10), the OutD protein of Erwinia carotovora (11), the XcpQ protein of Pseudomonas aeruginosa (12),and the ExeD protein of Aeromonas hydrophila (13) have been shown to be involved in the same type of secretion pathway. In addition, between 11 to 13 more genes in each of these bacteria are required for the second step of secretion (5,6).…”

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confidence: 99%

XpsD, an Outer Membrane Protein Required for Protein Secretion by Xanthomonas campestris pv. campestris, Forms a Multimer

Chen

Miaw

et al. 1996

Journal of Biological Chemistry

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confidence: 99%

XpsD, an Outer Membrane Protein Required for Protein Secretion by Xanthomonas campestris pv. campestris, Forms a Multimer

Chen

Miaw

et al. 1996

Journal of Biological Chemistry

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“…First, we generated insertion mutations of gspD and gspE in DC3000 using pKnockout-W. The gspD and gspE genes were selected based on the observation that homologues of these genes in Erwinia chrysanthemi are essential for type II secretion (42). The resulting strains, PBGspD and PBGspE, were confirmed to have insertions in gspD and gspE, respectively.…”

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Identification of a Twin-Arginine Translocation System in Pseudomonas syringae pv. tomato DC3000 and Its Contribution to Pathogenicity and Fitness

et al. 2005

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The bacterial plant pathogen Pseudomonas syringae pv. tomato DC3000 (DC3000) causes disease in Arabidopsis thaliana and tomato plants, and it elicits the hypersensitive response in nonhost plants such as Nicotiana tabacum and Nicotiana benthamiana. While these events chiefly depend upon the type III protein secretion system and the effector proteins that this system translocates into plant cells, additional factors have been shown to contribute to DC3000 virulence and still many others are likely to exist. Therefore, we explored the contribution of the twin-arginine translocation (Tat) system to the physiology of DC3000. We found that a tatC mutant strain of DC3000 displayed a number of phenotypes, including loss of motility on soft agar plates, deficiency in siderophore synthesis and iron acquisition, sensitivity to copper, loss of extracellular phospholipase activity, and attenuated virulence in host plant leaves. In the latter case, we provide evidence that decreased virulence of tatC mutants likely arises from a synergistic combination of (i) compromised fitness of bacteria in planta; (ii) decreased efficiency of type III translocation; and (iii) cytoplasmically retained virulence factors. Finally, we demonstrate a novel broad-host-range genetic reporter based on the green fluorescent protein for the identification of Tat-targeted secreted virulence factors that should be generally applicable to any gram-negative bacterium. Collectively, our evidence supports the notion that virulence of DC3000 is a multifactorial process and that the Tat system is an important virulence determinant of this phytopathogenic bacterium.The hallmark of the Pseudomonas syringae infection process is the injection of virulence effector proteins directly into host cells via the type III secretion mechanism (TTSS) (14). For efficient translocation of effector proteins, P. syringae must first establish productive contact with a target plant cell. This entails secretion of exopolysaccharides, cell wall-degrading enzymes, plant hormones, and several low-molecular-weight phytotoxins, such as coronatine and syringomycin (1, 30). Since many of these factors are secreted in a type III-independent manner and since deletion of many of these virulence factors often does not render P. syringae avirulent, it can be assumed that P. syringae virulence is multifactorial. Moreover, given the complexity of interactions that occur at the host-pathogen interface, there are likely many additional virulence determinants in P. syringae yet to be discovered.One possible contributor to P. syringae pathogenesis is the twin-arginine translocation (Tat) pathway that operates in the inner membrane of many gram-negative bacteria (4, 5, 56). Tat substrates are synthesized with cleavable N-terminal signal peptides that are characterized by a highly conserved twinarginine motif in the positively charged N-terminal region, a weakly hydrophobic core region, and a positively charged Sec pathway-avoidance signal in the C-terminal region (7,17). The most remarkable feat...

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“…The genes for these proteins are present as part of large operons required for secretion. Members of this family include pulE, required for pullulanase secretion in Klebsiella oxytoca (43); outE, required for secretion of pectate lyases and cellulases in Erwinia chrysanthemi (35); xcpR, required for secretion of toxin A, lipases, and proteases in Pseudomonas aeruginosa (4); pilB, required for pilin biogenesis in P. aeruginosa (39); and xpsE, required for secretion of proteases and cellulases in Xanthomonas campestris (15). PulE protein has been localized to the membrane fraction in E. coli in the presence or the absence of the other pul genes even though it, like VirB11, lacks an N-terminal secretion signal (12,43,44).…”

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Agrobacterium tumefaciens VirB11 protein requires a consensus nucleotide-binding site for function in virulence

1995

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virB11, one of the 11 genes of the virB operon, is absolutely required for transport of T-DNA from Agrobacterium tumefaciens into plant cells. Previous studies reported that VirB11 is an ATPase with autophosphorylation activity and localizes to the inner membrane even though the protein does not contain the consensus N-terminal export sequence. In this report, we show that VirB11 localizes to the inner membrane even in the absence of other tumor-inducing (Ti) plasmid-encoded proteins. To facilitate the further characterization of VirB11, we purified this protein from the soluble fraction of an Escherichia coli extract by fusing VirB11 to the maltose-binding protein. The maltose-binding protein-VirB11 fusion was able to complement a virB11 deletion mutant of A. tumefaciens for tumor formation and also localized properly to the inner membrane of A. tumefaciens. The 72-kDa protein, purified from E. coli, exhibited no autophosphorylation, ATPase activity, or ATP-binding activity. To study the importance of the Walker nucleotide-binding site present in VirB11, mutations were generated to replace the conserved lysine residue with either alanine or arginine. Expression of the virB11K175A mutant gene resulted in an avirulent phenotype, and expression of the virB11K175R mutant gene gave rise to an attenuated virulence phenotype. Both mutant proteins were present at levels three to four times higher than that of VirB11 in the wild-type strain. The mutant genes did not exhibit a transdominant phenotype on tumor formation in bacteria that were expressing wild-type virB11. The mutant proteins also localized properly to the inner membrane of A. tumefaciens, but the VirB11K175R protein appeared to be unstable after lysis of the cells.The soil bacterium Agrobacterium tumefaciens causes the plant disease crown gall. The bacteria can infect dicotyledonous plants at a wound site and induce the formation of tumors at the site of infection. Virulent strains of A. tumefaciens contain a large tumor-inducing (Ti) plasmid that carries the factors responsible for formation of the crown gall tumors. The bacteria have the unusual property of being able to transfer a segment of DNA (T-DNA) from the Ti plasmid into the host plant cells. The T-DNA is integrated into the plant genome, and expression of the oncogenes present in the T-DNA results in formation of the tumor (for recent reviews, see references 26, 70, and 73).The genes required for the transfer of T-DNA into the recipient plant cells are divided into eight vir operons on the octopine-type Ti plasmid (54). These genes are expressed only when the bacteria are exposed to wounded plant cells as a result of the action of several plant signal molecules acting in concert with the virA and virG gene products. Once the vir genes have been expressed, the gene products act in a coordinated fashion to synthesize T-DNA strands and direct the transfer of the T-DNA into a recipient plant cell.The T-DNA and associated proteins are transported through the bacterial inner and outer membranes and thr...

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Analysis of eight out genes in a cluster required for pectic enzyme secretion by Erwinia chrysanthemi: sequence comparison with secretion genes from other gram-negative bacteria

Cited by 106 publications

References 43 publications

XpsD, an Outer Membrane Protein Required for Protein Secretion by Xanthomonas campestris pv. campestris, Forms a Multimer

XpsD, an Outer Membrane Protein Required for Protein Secretion by Xanthomonas campestris pv. campestris, Forms a Multimer

Identification of a Twin-Arginine Translocation System in Pseudomonas syringae pv. tomato DC3000 and Its Contribution to Pathogenicity and Fitness

Agrobacterium tumefaciens VirB11 protein requires a consensus nucleotide-binding site for function in virulence

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