Contribution of the type II secretion system in systemic infectivity of Ralstonia solanacearum through xylem vessels

Tsujimoto, Shintaro; Nakaho, Kazuhiro; Adachi, Masanori; Ohnishi, Kouhei; Kiba, Akinori; Hikichi, Yasufumi

doi:10.1007/s10327-007-0061-5

Cited by 17 publications

(14 citation statements)

References 25 publications

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“…Therefore, it is thought that the main virulence factor of R. solanacearum is EPS, production of which could quantitatively control virulence. Cellulolytic enzymes, such as pectin lyases and cellulases enzymes, are also thought to be involved in quantitatively controlling the virulence of this bacterium (Liu et al ., 2005; Tsujimoto et al ., 2008).…”

Section: Introductionmentioning

confidence: 99%

Implication of C‐terminal mutation of PopA of Ralstonia solanacearum strain OE1‐1 in suppression of bacterial wilt

et al. 2009

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Ralstonia solanacearum strain OE1-1 causes bacterial wilt on tobacco plants. The popA -mutant 31b, derived from OE1-1 by insertion of transposon Tn 4431 , did not cause wilt on tobacco plants inoculated through the roots. However, when 31b was directly inoculated into xylem vessels, the tobacco plants wilted, similarly to those inoculated with OE1-1. 31b retained its exopolysaccharide productivity and its type-III secretion function. Furthermore, 31b grew in intercellular spaces and systemically infected tobacco plants, similarly to OE1-1. popA consists of an operon with popB and popC , and suppression of popB and popC expression resulting from polar mutation by transposon insertion did not affect the virulence of 31b. The mutated popA ( popA31b ) was composed of 960 nucleotides, including 39 derived from Tn 4431. A recombinant mutant from OE1-1, where popA31b was introduced by marker exchange, showed the same phenotype as 31b. PopA31b protein was extracellularly secreted by 31b co-cultured with Arabidopsis thaliana . These results suggest that PopA31b extracellularly secreted by 31b in intercellular spaces may be implicated in suppression of disease development, leading to inability of the bacteria to induce wilt on plants. Taken together, interactions between host plants and R. solanacearum existing in intercellular spaces immediately after invasion may be involved in disease development.

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Section: Introductionmentioning

confidence: 99%

Implication of C‐terminal mutation of PopA of Ralstonia solanacearum strain OE1‐1 in suppression of bacterial wilt

et al. 2009

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“…Bacteria, therefore, often secrete cell wall-degrading enzymes, which contribute to bacterial virulence and include, e.g., cellulases, xylanases, polygalacturonases, and amylases (2-6). It is assumed that the degradation of plant cell wall components by bacterial enzymes facilitates the acquisition of nutrients as well as the translocation of virulence factors into the host cell (7)(8)(9)(10)(11)(12)(13)(14).Bacterial extracellular enzymes are often secreted by a type II secretion (T2S) system, which is a major virulence factor of many Gram-negative plant-pathogenic bacteria, including Ralstonia solanacearum and species of Erwinia and Xanthomonas (8,(15)(16)(17)(18). T2S is a two-step process that often requires the Sec system for protein transport across the inner membrane (IM) (18,19).…”

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“…Bacterial extracellular enzymes are often secreted by a type II secretion (T2S) system, which is a major virulence factor of many Gram-negative plant-pathogenic bacteria, including Ralstonia solanacearum and species of Erwinia and Xanthomonas (8,(15)(16)(17)(18). T2S is a two-step process that often requires the Sec system for protein transport across the inner membrane (IM) (18,19).…”

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Xanthomonas campestris pv. vesicatoria Secretes Proteases and Xylanases via the Xps Type II Secretion System and Outer Membrane Vesicles

et al. 2015

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Many plant-pathogenic bacteria utilize type II secretion (T2S) systems to secrete degradative enzymes into the extracellular milieu. T2S substrates presumably mediate the degradation of plant cell wall components during the host-pathogen interaction and thus promote bacterial virulence. Previously, the Xps-T2S system from Xanthomonas campestris pv. vesicatoria was shown to contribute to extracellular protease activity and the secretion of a virulence-associated xylanase. The identities and functions of additional T2S substrates from X. campestris pv. vesicatoria, however, are still unknown. In the present study, the analysis of 25 candidate proteins from X. campestris pv. vesicatoria led to the identification of two type II secreted predicted xylanases, a putative protease and a lipase which was previously identified as a virulence factor of X. campestris pv. vesicatoria. Studies with mutant strains revealed that the identified xylanases and the protease contribute to virulence and in planta growth of X. campestris pv. vesicatoria. When analyzed in the related pathogen X. campestris pv. campestris, several T2S substrates from X. campestris pv. vesicatoria were secreted independently of the T2S systems, presumably because of differences in the T2S substrate specificities of the two pathogens. Furthermore, in X. campestris pv. vesicatoria T2S mutants, secretion of T2S substrates was not completely absent, suggesting the contribution of additional transport systems to protein secretion. In line with this hypothesis, T2S substrates were detected in outer membrane vesicles, which were frequently observed for X. campestris pv. vesicatoria. We, therefore, propose that extracellular virulence-associated enzymes from X. campestris pv. vesicatoria are targeted to the Xps-T2S system and to outer membrane vesicles. IMPORTANCEThe virulence of plant-pathogenic bacteria often depends on TS2 systems, which secrete degradative enzymes into the extracellular milieu. T2S substrates are being studied in several plant-pathogenic bacteria, including Xanthomonas campestris pv. vesicatoria, which causes bacterial spot disease in tomato and pepper. Here, we show that the T2S system from X. campestris pv. vesicatoria secretes virulence-associated xylanases, a predicted protease, and a lipase. Secretion assays with the related pathogen X. campestris pv. campestris revealed important differences in the T2S substrate specificities of the two pathogens. Furthermore, electron microscopy showed that T2S substrates from X. campestris pv. vesicatoria are targeted to outer membrane vesicles (OMVs). Our results, therefore, suggest that OMVs provide an alternative transport route for type II secreted extracellular enzymes. Many Gram-negative plant-pathogenic bacteria utilize specialized protein secretion systems to deliver virulence factors, including DNA or bacterial effector proteins, into plant cells (1). The efficient trans-kingdom transport of bacterial effector proteins is often hindered by the rigid plant cell wall, which mainly cons...

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“…OE1-1 possesses hrp genes, similar to R. solanacearum strain GMI1000, which is virulent on tomato plants and elicits a hypersensitivity response in infiltrated tobacco leaves (2,5,19,34). After vigorous proliferation in intercellular spaces, OE1-1 invaded xylem vessels and then systemically infected the whole plant (17,32,33). The hrp mutants of OE1-1 lose their ability not only to proliferate in intercellular spaces but also to systemically infect the whole plant.…”

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“…The resultant XbaI-and HindIII-digested 3.3-kbp DNA fragment was ligated into XbaI-and HindIII-digested pK18mobsacB (30) to create pK18mobsacBRS3. This plasmid was electroporated into OE1-1 cells (1,33), and kanamycin-resistant and sucrose-sensitive recombinants were selected. The recombinant was incubated in a rich medium (PS medium) (17) for 6 h and a kanamycin-sensitive and sucroseresistant recombinant, OE1102, was selected.…”

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An Amino Acid Substitution at Position 740 in σ ⁷⁰ of Ralstonia solanacearum Strain OE1-1 Affects Its In Planta Growth

Kanda

Tsuneishi

Mori

et al. 2008

Appl Environ Microbiol

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Growth of Ralstonia solanacearum strain OE1-1 in roots after invasion is required for virulence. An Arg740Cys substitution in 70 of OE1-1 resulted in loss of in planta growth and virulence. The negative dominance of mutant 70 over the wild-type protein suggested that the amino acid substitution may affect the in planta growth of OE1-1, leading to a lack of virulence.Ralstonia solanacearum strain OE1-1 shows virulence on tobacco, as well as tomato and eggplant, plants (17). OE1-1 possesses hrp genes, similar to R. solanacearum strain GMI1000, which is virulent on tomato plants and elicits a hypersensitivity response in infiltrated tobacco leaves (2,5,19,34). After vigorous proliferation in intercellular spaces, OE1-1 invaded xylem vessels and then systemically infected the whole plant (17,32,33). The hrp mutants of OE1-1 lose their ability not only to proliferate in intercellular spaces but also to systemically infect the whole plant. Therefore, it is thought that proliferation of the bacteria in intercellular spaces after invasion of roots qualitatively control bacterial virulence.The hrp genes encode proteins that construct the type III secretion system. In R. solanacearum, expression of hrp genes is regulated by the HrpB protein (2, 13, 34). Screening of genes controlled by HrpB has isolated many candidates for type III effector genes in R. solanacearum (9,25). Moreover, by in vivo expression technology, genes expressed in R. solanacearum K60-infected tomato plants were isolated (6). However, the involvement of these candidates in the bacterium-host plant interactions remains to be elucidated. Furthermore, analysis by in vivo expression technology indicates that genes other than hrp and type III secretion system effector genes are involved in bacterial virulence (6, 7).To elucidate the mechanism of vigorous growth of OE1-1 in roots in this study, we first selected mutants that lack systemic infectivity and do not provoke disease in tobacco plants. The suicide vector pUTSm/Sp (10) containing mini-Tn5, which includes the spectinomycin resistance gene, was transferred from Escherichia coli HB101 (Takara, Ohtsu, Japan) to OE1-1 by conjugation with E. coli HB101(pRK2013) (12). The roots of 8-week-old tobacco plants (Nicotiana tabacum cv. Bright Yellow) were soaked in a bacterial suspension (1.0 ϫ 10 8 CFU/ml) of 421 spectinomycin-resistant mutants derived from OE1-1 for 30 min, and then inoculated plants were grown in water culture pots (Yamato water culture pot no. 1; Yamato Plastic Co. Ltd., Tokyo, Japan) with one-fifth-strength Hoagland's solution in a growth room at 25°C under 10,000 lx for 16 h/day (root dipping) (17). Each assay was repeated in five successive trials, and within each trial we treated five plants with each strain. Only one mutant, OE1101, lacked the ability to cause wilt in tobacco plants. Seven days after inoculation by root dipping, the stems of five tobacco plants were cut into three pieces with razor blades (Fig. 1). The cut site of each piece was pressed onto Hara-Ono medium (15) for OE1-...

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Contribution of the type II secretion system in systemic infectivity of Ralstonia solanacearum through xylem vessels

Cited by 17 publications

References 25 publications

Implication of C‐terminal mutation of PopA of Ralstonia solanacearum strain OE1‐1 in suppression of bacterial wilt

Implication of C‐terminal mutation of PopA of Ralstonia solanacearum strain OE1‐1 in suppression of bacterial wilt

Xanthomonas campestris pv. vesicatoria Secretes Proteases and Xylanases via the Xps Type II Secretion System and Outer Membrane Vesicles

An Amino Acid Substitution at Position 740 in σ ⁷⁰ of Ralstonia solanacearum Strain OE1-1 Affects Its In Planta Growth

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Contribution of the type II secretion system in systemic infectivity of Ralstonia solanacearum through xylem vessels

Cited by 17 publications

References 25 publications

Implication of C‐terminal mutation of PopA of Ralstonia solanacearum strain OE1‐1 in suppression of bacterial wilt

Implication of C‐terminal mutation of PopA of Ralstonia solanacearum strain OE1‐1 in suppression of bacterial wilt

Xanthomonas campestris pv. vesicatoria Secretes Proteases and Xylanases via the Xps Type II Secretion System and Outer Membrane Vesicles

An Amino Acid Substitution at Position 740 in σ 70 of Ralstonia solanacearum Strain OE1-1 Affects Its In Planta Growth

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An Amino Acid Substitution at Position 740 in σ ⁷⁰ of Ralstonia solanacearum Strain OE1-1 Affects Its In Planta Growth