scholarly journals Comparative Analysis of Type III Secreted Effector Genes Reflects Divergence of Acidovorax citrulli Strains into Three Distinct Lineages

2014 ◽  
Vol 104 (11) ◽  
pp. 1152-1162 ◽  
Author(s):  
Noam Eckshtain-Levi ◽  
Tamar Munitz ◽  
Marija Živanović ◽  
Sy M. Traore ◽  
Cathrin Spröer ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Citrullus Lanatus ◽  
Housekeeping Genes ◽  
Type Iii ◽  
Effector Genes ◽  
Acidovorax Citrulli ◽  
Group I ◽  
Group Ii

Acidovorax citrulli causes bacterial fruit blotch of cucurbits, a serious economic threat to watermelon (Citrullus lanatus) and melon (Cucumis melo) production worldwide. Based on genetic and biochemical traits, A. citrulli strains have been divided into two distinct groups: group I strains have been mainly isolated from various non-watermelon hosts, while group II strains have been generally isolated from and are highly virulent on watermelon. The pathogen depends on a functional type III secretion system for pathogenicity. Annotation of the genome of the group II strain AAC00-1 revealed 11 genes encoding putative type III secreted (T3S) effectors. Due to the crucial role of type III secretion for A. citrulli pathogenicity, we hypothesized that group I and II strains differ in their T3S effector repertoire. Comparative analysis of the 11 effector genes from a collection of 22 A. citrulli strains confirmed this hypothesis. Moreover, this analysis led to the identification of a third A. citrulli group, which was supported by DNA:DNA hybridization, DNA fingerprinting, multilocus sequence analysis of conserved genes, and virulence assays. The effector genes assessed in this study are homologous to effectors from other plant-pathogenic bacteria, mainly belonging to Xanthomonas spp. and Ralstonia solanacearum. Analyses of the effective number of codons and gas chromatography content of effector genes relative to a representative set of housekeeping genes support the idea that these effector genes were acquired by lateral gene transfer. Further investigation is required to identify new T3S effectors of A. citrulli and to determine their contribution to virulence and host preferential association.

scholarly journals Natural variation in a short region of the Acidovorax citrulli type III-secreted effector AopW1 is associated with differences in cytotoxicity

2021 ◽  
Author(s):  
IRENE JIMENEZ-GUERRERO ◽  
MONICA SONAWANE ◽  
NOAM ECKSHTAIN-LEVI ◽  
GUSTAVO M. DA SILVA ◽  
FRANCISCO PEREZ-MONTANO ◽  
...  
Keyword(s):  
Amino Acid ◽  
Pseudomonas Syringae ◽  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Variable Region ◽  
Callose Deposition ◽  
Type Iii ◽  
Acidovorax Citrulli ◽  
Group I ◽  
Group Ii

Bacterial fruit blotch (BFB) is a serious disease of melon and watermelon caused by the Gram-negative bacterium Acidovorax citrulli. The strains of the pathogen can be divided into two major genetic groups, I and II. While group I strains are strongly associated with melon, group II strains are more aggressive on watermelon. Like many pathogenic bacteria, A. citrulli secretes a variety of protein effectors to the host cell via the type III secretion system. In the present study, we characterized AopW1, an A. citrulli type III-secreted effector that shares similarity with the actin cytoskeleton-disrupting effector HopW1 of Pseudomonas syringae and with effectors from other plant-pathogenic bacterial species. aopW1 is present in group I and II strains, encoding products of 485 amino acids. Although highly conserved in most of the sequence, AopW1 has a highly variable region (HVR) within amino acid positions 147 to 192, including 14 amino acid differences between groups. Here we show that group I AopW1 is more toxic to yeast and plant cells than group II AopW1, having a stronger actin filament disruption activity, and increased ability to reduce plant callose deposition. We demonstrate the role of some of these 14 amino acid positions in determining the phenotypic differences between the two versions of the effector. Moreover, cellular analyses revealed that in addition to the interaction with actin filaments, AopW1 is localized to the endoplasmic reticulum, chloroplasts, and early and recycling plant endosomes, with differences observed between the two AopW1 versions. Finally, we show that overexpression of the endosome-associated protein EHD1 that increases cellular recycling, attenuates the toxic effects exerted by AopW1 and increases defence responses. This study provides insights into the HopW1 family of bacterial effectors and their interactions with the plant cell and provides first evidence on the involvement of EHD1 in response to biotic stress.

scholarly journals Show me your secret(ed) weapons: a multifaceted approach reveals novel type III-secreted effectors of a plant pathogenic bacterium

2019 ◽  
Author(s):  
Irene Jiménez Guerrero ◽  
Francisco Pérez-Montaño ◽  
Gustavo Mateus da Silva ◽  
Naama Wagner ◽  
Dafna Shkedy ◽  
...  
Keyword(s):  
Machine Learning ◽  
Endoplasmic Reticulum ◽  
Cell Nucleus ◽  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Gram Negative ◽  
Type Iii ◽  
Acidovorax Citrulli

AbstractMany Gram-negative plant and animal pathogenic bacteria employ a type III secretion system (T3SS) to secrete protein effectors into the cells of their hosts and promote disease. The plant pathogen Acidovorax citrulli requires a functional T3SS for pathogenicity. As with Xanthomonas and Ralstonia spp., an AraC-type transcriptional regulator, HrpX, regulates expression of genes encoding T3SS components and type III-secreted effectors (T3Es) in A. citrulli. A previous study reported eleven T3E genes in this pathogen, based on the annotation of a sequenced strain. We hypothesized that this was an underestimation. Guided by this hypothesis, we aimed at uncovering the T3E arsenal of the A. citrulli model strain, M6. We carried out a thorough sequence analysis searching for similarity to known T3Es from other bacteria. This analysis revealed 51 A. citrulli genes whose products are similar to known T3Es. Further, we combined machine learning and transcriptomics to identify novel T3Es. The machine learning approach ranked all A. citrulli M6 genes according to their propensity to encode T3Es. RNA-Seq revealed differential gene expression between wild-type M6 and a mutant defective in HrpX. Data combined from these approaches led to the identification of seven novel T3E candidates, that were further validated using a T3SS-dependent translocation assay. These T3E genes encode hypothetical proteins, do not show any similarity to known effectors from other bacteria, and seem to be restricted to plant pathogenic Acidovorax species. Transient expression in Nicotiana benthamiana revealed that two of these T3Es localize to the cell nucleus and one interacts with the endoplasmic reticulum. This study not only uncovered the arsenal of T3Es of an important pathogen, but it also places A. citrulli among the “richest” bacterial pathogens in terms of T3E cargo. It also revealed novel T3Es that appear to be involved in the pathoadaptive evolution of plant pathogenic Acidovorax species.Author summaryAcidovorax citrulli is a Gram-negative bacterium that causes bacterial fruit blotch (BFB) disease of cucurbits. This disease represents a serious threat to cucurbit crop production worldwide. Despite the agricultural importance of BFB, the knowledge about basic aspects of A. citrulli-plant interactions is rather limited. As many Gram-negative plant and animal pathogenic bacteria, A. citrulli employs a complex secretion system, named type III secretion system, to deliver protein virulence effectors into the host cells. In this work we aimed at uncovering the arsenal of type III-secreted effectors (T3Es) of this pathogen by combination of bioinformatics and experimental approaches. We found that this bacterium possesses at least 51 genes that are similar to T3E genes from other pathogenic bacteria. In addition, our study revealed seven novel T3Es that seem to occur only in A. citrulli strains and in other plant pathogenic Acidovorax species. We found that two of these T3Es localize to the plant cell nucleus while one partially interacts with the endoplasmic reticulum. Further characterization of the novel T3Es identified in this study may uncover new host targets of pathogen effectors and new mechanisms by which pathogenic bacteria manipulate their hosts.

scholarly journals Pseudomonas syringae Strains Naturally Lacking the Classical P. syringae hrp/hrc Locus Are Common Leaf Colonizers Equipped with an Atypical Type III Secretion System

2010 ◽  
Vol 23 (2) ◽  
pp. 198-210 ◽  
Author(s):  
Christopher R. Clarke ◽  
Rongman Cai ◽  
David J. Studholme ◽  
David S. Guttman ◽  
Boris A. Vinatzer
Keyword(s):  
Pseudomonas Syringae ◽  
Type Iii Secretion ◽  
Plant Cells ◽  
Type Iii Secretion System ◽  
Ice Nucleation ◽  
Secretion System ◽  
Effector Proteins ◽  
Population Densities ◽  
Type Iii ◽  
Effector Genes

Pseudomonas syringae is best known as a plant pathogen that causes disease by translocating immune-suppressing effector proteins into plant cells through a type III secretion system (T3SS). However, P. syringae strains belonging to a newly described phylogenetic subgroup (group 2c) are missing the canonical P. syringae hrp/hrc cluster coding for a T3SS, flanking effector loci, and any close orthologue of known P. syringae effectors. Nonetheless, P. syringae group 2c strains are common leaf colonizers and grow on some tested plant species to population densities higher than those obtained by other P. syringae strains on nonhost species. Moreover, group 2c strains have genes necessary for the production of phytotoxins, have an ice nucleation gene, and, most interestingly, contain a novel hrp/hrc cluster, which is only distantly related to the canonical P. syringae hrp/hrc cluster. This hrp/hrc cluster appears to encode a functional T3SS although the genes hrpK and hrpS, present in the classical P. syringae hrp/hrc cluster, are missing. The genome sequence of a representative group 2c strain also revealed distant orthologues of the P. syringae effector genes avrE1 and hopM1 and the P. aeruginosa effector genes exoU and exoY. A putative life cycle for group 2c P. syringae is discussed.

scholarly journals Comparative Analysis of the Intrastromal MyoRing Implantation performed with the Femtosecond Laser

2017 ◽  
Vol 6 (2) ◽  
pp. 49-57
Author(s):  
Maksim V Sinitsyn ◽  
Nadezhda A Pozdeyeva ◽  
Nikolai P Pashtayev
Keyword(s):  
Comparative Analysis ◽  
Femtosecond Laser ◽  
Corneal Thickness ◽  
Functional Results ◽  
Standard Group ◽  
Pronounced Increase ◽  
Group I ◽  
Biomechanical Parameters ◽  
Group Ii

ABSTRACT Purpose To comparatively analyze the intrastromal MyoRing implantation with femtosecond laser (FL) using the standard and optimized technologies in the experiment and based on the long-term clinical-functional results of the patients with keratoconus (KC) at stages II and III. Materials and methods The experimental work was performed on 24 eyes of rabbits. All eyes were divided into six groups according to the method of operation. In the clinical part of the research, the surgical treatment of 70 patients (76 eyes) with KC at stages II and III was done. Depending on the technology of the operation, all patients were divided into two groups. Group I consisted of 29 patients (32 eyes) with KC, in which MyoRing implantation was performed according to the standard, group II consisted of 31 patients (32 eyes) with KC, in which MyoRing implantation was performed according to the optimized technology. Results Higher voltage was required for stretching samples of the second group in comparison with the third and the sixth group in comparison with the fifth group. In group I, during the period of 6 to 36 months the surgery reverses keratometry, corneal thickness above the MyoRing, and posterior corneal elevation. In group II, 12 months after surgery the clinical and functional parameters remained stable throughout the period of observation. Conclusion Greater reduction in corneal biomechanical stability was observed after formation of the intrastromal pocket in comparison with an intrastromal tunnel; a more pronounced increase in the strength characteristics of the cornea was observed after implantation of the ring in intrastromal pocket, compared with implantation intracorneal segments in intrastromal tunnel, and with increasing depth of intrastromal ring implantation. Application of optimized MyoRing implantation technology compared with standard allows more biomechanical parameters of the cornea to improve and reduce the risk of the ring protrusion. How to cite this article Sinitsyn MV, Pozdeyeva NA, Pashtayev NP. Comparative Analysis of the Intrastromal MyoRing Implantation performed with the Femtosecond Laser. Int J Kerat Ect Cor Dis 2017;6(2):49-57.

scholarly journals The Contribution of the Predicted Sorting Platform Component HrcQ to Type III Secretion in Xanthomonas campestris pv. vesicatoria Depends on an Internal Translation Start Site

2021 ◽  
Vol 12 ◽  
Author(s):  
Christian Otten ◽  
Tanja Seifert ◽  
Jens Hausner ◽  
Daniela Büttner
Keyword(s):  
Type Iii Secretion ◽  
Structural Component ◽  
Xanthomonas Campestris ◽  
Pathogenic Bacteria ◽  
Start Site ◽  
Translation Start Site ◽  
Terminal Protein ◽  
Type Iii ◽  
Translation Start ◽  
Membrane Spanning

Pathogenicity of the Gram-negative bacterium Xanthomonas campestris pv. vesicatoria depends on a type III secretion (T3S) system which translocates effector proteins into plant cells. T3S systems are conserved in plant- and animal-pathogenic bacteria and consist of at least nine structural core components, which are designated Sct (secretion and cellular translocation) in animal-pathogenic bacteria. Sct proteins are involved in the assembly of the membrane-spanning secretion apparatus which is associated with an extracellular needle structure and a cytoplasmic sorting platform. Components of the sorting platform include the ATPase SctN, its regulator SctL, and pod-like structures at the periphery of the sorting platform consisting of SctQ proteins. Members of the SctQ family form a complex with the C-terminal protein domain, SctQC, which is translated as separate protein and likely acts either as a structural component of the sorting platform or as a chaperone for SctQ. The sorting platform has been intensively studied in animal-pathogenic bacteria but has not yet been visualized in plant pathogens. We previously showed that the SctQ homolog HrcQ from X. campestris pv. vesicatoria assembles into complexes which associate with the T3S system and interact with components of the ATPase complex. Here, we report the presence of an internal alternative translation start site in hrcQ leading to the separate synthesis of the C-terminal protein region (HrcQC). The analysis of genomic hrcQ mutants showed that HrcQC is essential for pathogenicity and T3S. Increased expression levels of hrcQ or the T3S genes, however, compensated the lack of HrcQC. Interaction studies and protein analyses suggest that HrcQC forms a complex with HrcQ and promotes HrcQ stability. Furthermore, HrcQC colocalizes with HrcQ as was shown by fluorescence microscopy, suggesting that it is part of the predicted cytoplasmic sorting platform. In agreement with this finding, HrcQC interacts with the inner membrane ring protein HrcD and the SctK-like linker protein HrpB4 which contributes to the docking of the HrcQ complex to the membrane-spanning T3S apparatus. Taken together, our data suggest that HrcQC acts as a chaperone for HrcQ and as a structural component of the predicted sorting platform.

scholarly journals Identification of Novel Type III Secretion Effectors in Xanthomonas oryzae pv. oryzae

2009 ◽  
Vol 22 (1) ◽  
pp. 96-106 ◽  
Author(s):  
Ayako Furutani ◽  
Minako Takaoka ◽  
Harumi Sanada ◽  
Yukari Noguchi ◽  
Takashi Oku ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Regulatory Protein ◽  
Effector Proteins ◽  
Xanthomonas Oryzae ◽  
Dependent Manner ◽  
Plant Pathogenic Bacteria ◽  
Type Iii ◽  
Genes Encoding

Many gram-negative bacteria secrete so-called effector proteins via a type III secretion (T3S) system. Through genome screening for genes encoding potential T3S effectors, 60 candidates were selected from rice pathogen Xanthomonas oryzae pv. oryzae MAFF311018 using these criteria: i) homologs of known T3S effectors in plant-pathogenic bacteria, ii) genes with expression regulated by hrp regulatory protein HrpX, or iii) proteins with N-terminal amino acid patterns associated with T3S substrates of Pseudomonas syringae. Of effector candidates tested with the Bordetella pertussis calmodulin-dependent adenylate cyclase reporter for translocation into plant cells, 16 proteins were translocated in a T3S system-dependent manner. Of these 16 proteins, nine were homologs of known effectors in other plant-pathogenic bacteria and seven were not. Most of the effectors were widely conserved in Xanthomonas spp.; however, some were specific to X. oryzae. Interestingly, all these effectors were expressed in an HrpX-dependent manner, suggesting coregulation of effectors and the T3S system. In X. campestris pv. vesicatoria, HpaB and HpaC (HpaP in X. oryzae pv. oryzae) have a central role in recruiting T3S substrates to the secretion apparatus. Secretion of all but one effector was reduced in both HpaB– and HpaP– mutant strains, indicating that HpaB and HpaP are widely involved in efficient secretion of the effectors.

scholarly journals Characterization, Phylogeny, and Genome Analyses of Nonpathogenic Xanthomonas campestris Strains Isolated from Brassica Seeds

2020 ◽  
Vol 110 (5) ◽  
pp. 981-988 ◽  
Author(s):  
Yung-An Lee ◽  
Pei-Yu Yang ◽  
Shau-Chang Huang
Keyword(s):  
Type Iii Secretion ◽  
Xanthomonas Campestris ◽  
Pathogenicity Island ◽  
Whole Genome Sequence ◽  
Effector Protein ◽  
Type Iii Effector ◽  
Type Iii ◽  
Effector Genes ◽  
Genome Analyses ◽  
Xanthomonas Campestris Pv Campestris

Xanthomonads were detected by using the Xan-D(CCF) medium from the brassica seeds, and their pathogenicity was determined by plant inoculation tests. It was found that some seed lots were infested with Xanthomonas campestris pv. campestris, some with X. campestris pv. raphani, and some with nonpathogenic xanthomonads. The nonpathogenic xanthomonad strains were identified as X. campestris, and the multilocus sequence analysis showed that the nonpathogenic X. campestris strains were grouped together with pathogenic X. campestris, but not with nonpathogenic strains of X. arboricola. In addition, all isolated X. campestris pv. campestris and X. campestris pv. raphani strains were positive in the hrpF-PCR, but the nonpathogenic strains were negative. It was further found that nonpathogenic X. campestris strain nE1 does not contain the entire pathogenicity island (hrp gene cluster; type III secretion system) and all type III effector protein genes based on the whole genome sequence analyses. The nonpathogenic X. campestris strain nE1 could acquire the entire pathogenicity island from the endemic X. campestris pv. campestris and X. campestris pv. raphani strains by conjugation, but type III effector genes were not cotransferred. The studies showed that the nonpathogenic X. campestris strains indeed exist on the brassica seeds, but it could be differentiated by the PCR assays on the hrp and type III effector genes. Nevertheless, the nonpathogenic X. campestris strains cannot be ignored because they may be potential gene resources to increase genetic diversity in the endemic pathogenic X. campestris pv. campestris and X. campestris pv. raphani strains.

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