Regulation of Tomato Prf by Pto-like Protein Kinases

Tomato Prf encodes a nucleotide-binding domain shared by Apaf-1, certain R proteins, and CED-4 fused to C-terminal leucine-rich repeats (NBARC-LRR) protein that is required for bacterial immunity to Pseudomonas syringae and sensitivity to the organophosphate fenthion. The signaling pathways involve two highly related protein kinases. Pto kinase mediates direct recognition of the bacterial effector proteins AvrPto or AvrPtoB. Fen kinase is required for fenthion sensitivity and recognition of bacterial effectors related to AvrPtoB. The role of Pto and its association with Prf has been characterized but Fen is poorly described. We show that, similar to Pto, Fen requires N-myristoylation and kinase activity for signaling and interacts with the N-terminal domain of Prf. Thus, the mechanisms of activation of Prf by the respective protein kinases are similar. Prf–Fen interaction is underlined by coregulatory mechanisms in which Prf negatively regulates Fen, most likely by controlling kinase activity. We further characterized negative regulation of Prf by Pto, and show that regulation is mediated by the previously described negative regulatory patch. Remarkably, the effectors released negative regulation of Prf in a manner dependent on Pto kinase activity. The data suggest a model in which Prf associates generally with Pto-like kinases in tightly regulated complexes, which are activated by effector-mediated disruption of negative regulation. Release of negative regulation may be a general feature of activation of NBARC-LRR proteins by cognate effectors.

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Tomato Prf requires NLR helpers NRC2 and NRC3 to confer resistance against the bacterial speck pathogen Pseudomonas syringae pv. tomato

10.1101/595744 ◽

2019 ◽

Cited By ~ 1

Author(s):

Chih-Hang Wu ◽

Sophien Kamoun

Keyword(s):

Cell Death ◽

Pseudomonas Syringae ◽

Effector Proteins ◽

Leucine Rich Repeat ◽

Nucleotide Binding Domain ◽

Hypersensitive Cell Death ◽

Tomato Production ◽

Bacterial Speck ◽

Solanaceous Plants ◽

Pto Kinase

AbstractBacterial speck, caused by the pathogen Pseudomonas syringae pv. tomato, is one of the most common diseases in tomato production. Together with Pto kinase, the NLR (nucleotide-binding domain leucine-rich repeat containing) protein Prf confers resistance against the bacterial speck pathogen by recognizing AvrPto and AvrPtoB, two Type III effector proteins secreted by P. syringae pv. tomato. This Prf/Pto pathway is part of a complex NLR network in solanaceous plants that mediates resistance to diverse pathogens through the helper NLR proteins NRCs (NLR required for cell death). We previously showed that, in Nicotiana benthamiana, the hypersensitive cell death elicited by expression of AvrPto and Pto, which activate immunity through the endogenous Prf ortholog NbPrf, requires functionally redundant NRC2 and NRC3. However, whether tomato (Solanum lycopersicum) Prf (SlPrf) confers resistance to the bacterial speck pathogen through NRC2 and NRC3 has not been determined. In this study, we show that SlPrf requires NRC2 and NRC3 to trigger hypersensitive cell death and disease resistance in both N. benthamiana and tomato. We found that the hypersensitive cell death induced by AvrPtoB/Pto/SlPrf in N. benthamiana is compromised when NRC2 and NRC3 are silenced, indicating that SlPrf is an NRC2/3-dependent NLR. We validated this finding by showing that silencing NRC2 and NRC3 in the bacterial speck resistant tomato ‘Rio Grande 76R’ compromised Prf-mediated resistance. These results indicate that the NRC network extends beyond N. benthamiana to solanaceous crops.

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BAK1 Is Not a Target of the Pseudomonas syringae Effector AvrPto

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-04-10-0096 ◽

2011 ◽

Vol 24 (1) ◽

pp. 100-107 ◽

Cited By ~ 49

Author(s):

Tingting Xiang ◽

Na Zong ◽

Jie Zhang ◽

Jinfeng Chen ◽

Mingsheng Chen ◽

...

Keyword(s):

Cell Surface ◽

Immune Responses ◽

Pseudomonas Syringae ◽

Plant Cell ◽

Crucial Role ◽

Pathogenic Bacteria ◽

Effector Proteins ◽

Receptor Like Kinase ◽

Receptor Kinases ◽

New Evidence

Plant cell surface-localized receptor kinases such as FLS2, EFR, and CERK1 play a crucial role in detecting invading pathogenic bacteria. Upon stimulation by bacterium-derived ligands, FLS2 and EFR interact with BAK1, a receptor-like kinase, to activate immune responses. A number of Pseudomonas syringae effector proteins are known to block immune responses mediated by these receptors. Previous reports suggested that both FLS2 and BAK1 could be targeted by the P. syringae effector AvrPto to inhibit plant defenses. Here, we provide new evidence further supporting that FLS2 but not BAK1 is targeted by AvrPto in plants. The AvrPto-FLS2 interaction prevented the phosphorylation of BIK1, a downstream component of the FLS2 pathway.

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The kinase activity of human Rio1 is required for final steps of cytoplasmic maturation of 40S subunits

Molecular Biology of the Cell ◽

10.1091/mbc.e11-07-0639 ◽

2012 ◽

Vol 23 (1) ◽

pp. 22-35 ◽

Cited By ~ 65

Author(s):

Barbara Widmann ◽

Franziska Wandrey ◽

Lukas Badertscher ◽

Emanuel Wyler ◽

Jens Pfannstiel ◽

...

Keyword(s):

Rna Interference ◽

Protein Kinases ◽

18S Rrna ◽

Kinase Activity ◽

Ribosomal Biogenesis ◽

Ribosomal Subunits ◽

Binding Partner ◽

Rrna Maturation ◽

Cytoplasmic Maturation

RIO proteins form a conserved family of atypical protein kinases. Humans possess three distinct RIO kinases—hRio1, hRio2, and hRio3, of which only hRio2 has been characterized with respect to its role in ribosomal biogenesis. Here we show that both hRio1 and hRio3, like hRio2, are associated with precursors of 40S ribosomal subunits in human cells. Furthermore, we demonstrate that depletion of hRio1 by RNA interference affects the last step of 18S rRNA maturation and causes defects in the recycling of several trans-acting factors (hEnp1, hRio2, hLtv1, hDim2/PNO1, and hNob1) from pre-40S subunits in the cytoplasm. Although the effects of hRio1 and hRio2 depletion are similar, we show that the two kinases are not fully interchangeable. Moreover, rescue experiments with a kinase-dead mutant of hRio1 revealed that the kinase activity of hRio1 is essential for the recycling of the endonuclease hNob1 and its binding partner hDim2 from cytoplasmic pre-40S. Kinase-dead hRio1 is trapped on pre-40S particles containing hDim2 and hNob1 but devoid of hEnp1, hLtv1, and hRio2. These data reveal a role of hRio1 in the final stages of cytoplasmic pre-40S maturation.

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What the Wild Things Do: Mechanisms of Plant Host Manipulation by Bacterial Type III-Secreted Effector Proteins

Microorganisms ◽

10.3390/microorganisms9051029 ◽

2021 ◽

Vol 9 (5) ◽

pp. 1029

Author(s):

Karl J. Schreiber ◽

Ilea J. Chau-Ly ◽

Jennifer D. Lewis

Keyword(s):

Pseudomonas Syringae ◽

Structural Data ◽

Enzymatic Activities ◽

Effector Proteins ◽

Host Recognition ◽

Plant Host ◽

Type Iii ◽

Xanthomonas Species ◽

Pathogen Fitness ◽

Enzymatic Mechanisms

Phytopathogenic bacteria possess an arsenal of effector proteins that enable them to subvert host recognition and manipulate the host to promote pathogen fitness. The type III secretion system (T3SS) delivers type III-secreted effector proteins (T3SEs) from bacterial pathogens such as Pseudomonas syringae, Ralstonia solanacearum, and various Xanthomonas species. These T3SEs interact with and modify a range of intracellular host targets to alter their activity and thereby attenuate host immune signaling. Pathogens have evolved T3SEs with diverse biochemical activities, which can be difficult to predict in the absence of structural data. Interestingly, several T3SEs are activated following injection into the host cell. Here, we review T3SEs with documented enzymatic activities, as well as T3SEs that facilitate virulence-promoting processes either indirectly or through non-enzymatic mechanisms. We discuss the mechanisms by which T3SEs are activated in the cell, as well as how T3SEs modify host targets to promote virulence or trigger immunity. These mechanisms may suggest common enzymatic activities and convergent targets that could be manipulated to protect crop plants from infection.

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

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-23-2-0198 ◽

2010 ◽

Vol 23 (2) ◽

pp. 198-210 ◽

Cited By ~ 69

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.

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HomoKinase: A Curated Database of Human Protein Kinases

ISRN Computational Biology ◽

10.1155/2013/417634 ◽

2013 ◽

Vol 2013 ◽

pp. 1-5 ◽

Cited By ~ 11

Author(s):

Suresh Subramani ◽

Saranya Jayapalan ◽

Raja Kalpana ◽

Jeyakumar Natarajan

Keyword(s):

Gene Ontology ◽

Protein Kinases ◽

Kinase Activity ◽

Query Protein ◽

Amino Acid Sequences ◽

Human Protein ◽

Biological Information ◽

Functional Domain ◽

Comprehensive Collection ◽

Search Tool

HomoKinase database is a comprehensive collection of curated human protein kinases and their relevant biological information. The entries in the database are curated by three criteria: HGNC approval, gene ontology-based biological process (protein phosphorylation), and molecular function (ATP binding and kinase activity). For a given query protein kinase name, the database provides its official symbol, full name, other known aliases, amino acid sequences, functional domain, gene ontology, pathways assignments, and drug compounds. In addition, as a search tool, it enables the retrieval of similar protein kinases with specific family, subfamily, group, and domain combinations and tabulates the information. The present version contains 498 curated human protein kinases and links to other popular databases.

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Genome context influences evolutionary flexibility of nearly identical type III effectors in two phytopathogenic Pseudomonads

10.1101/2021.11.22.469601 ◽

2021 ◽

Author(s):

David A Baltrus ◽

Qian Feng ◽

Brian H Kvitko

Keyword(s):

Pseudomonas Syringae ◽

Evolutionary Dynamics ◽

Effector Proteins ◽

In Planta ◽

Genomic Context ◽

Type Iii Effectors ◽

Type Iii ◽

Genome Context ◽

The Impact ◽

Multiple Type

Integrative Conjugative Elements (ICEs) are replicons that can insert and excise from chromosomal locations in a site specific manner, can conjugate across strains, and which often carry a variety of genes useful for bacterial growth and survival under specific conditions. Although ICEs have been identified and vetted within certain clades of the agricultural pathogen Pseudomonas syringae, the impact of ICE carriage and transfer across the entire P. syringae species complex remains underexplored. Here we identify and vet an ICE (PmaICE-DQ) from P. syringae pv. maculicola ES4326, a strain commonly used for laboratory virulence experiments, demonstrate that this element can excise and conjugate across strains, and contains loci encoding multiple type III effector proteins. Moreover, genome context suggests that another ICE (PmaICE-AOAB) is highly similar in comparison with and found immediately adjacent to PmaICE-DQ within the chromosome of strain ES4326, and also contains multiple type III effectors. Lastly, we present passage data from in planta experiments that suggests that genomic plasticity associated with ICEs may enable strains to more rapidly lose type III effectors that trigger R-gene mediated resistance in comparison to strains where nearly isogenic effectors are not present in ICEs. Taken together, our study sheds light on a set of ICE elements from P. syringae pv. maculicola ES4326 and highlights how genomic context may lead to different evolutionary dynamics for shared virulence genes between strains.

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

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-22-1-0096 ◽

2009 ◽

Vol 22 (1) ◽

pp. 96-106 ◽

Cited By ~ 71

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.

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Membrane localization of the kinase which phosphorylates p34cdc2 on threonine 14.

Molecular Biology of the Cell ◽

10.1091/mbc.5.3.273 ◽

1994 ◽

Vol 5 (3) ◽

pp. 273-282 ◽

Cited By ~ 70

Author(s):

S Kornbluth ◽

B Sebastian ◽

T Hunter ◽

J Newport

Keyword(s):

Cell Cycle ◽

Protein Kinase ◽

Schizosaccharomyces Pombe ◽

Protein Kinases ◽

Membrane Fraction ◽

Kinase Activity ◽

Serine Threonine Kinase ◽

Threonine Kinase ◽

Dual Specificity ◽

Detergent Extraction

The key regulator of entry into mitosis is the serine/threonine kinase p34cdc2. This kinase is regulated both by association with cyclins and by phosphorylation at several sites. Phosphorylation at Tyr 15 and Thr 14 are believed to inhibit the kinase activity of cdc2. In Schizosaccharomyces pombe, the wee1 (and possibly mik1) protein kinase catalyzes phosphorylation of Tyr 15. It is not clear whether these or other, as yet unidentified, protein kinases phosphorylate Thr 14. In this report we show, using extracts of Xenopus eggs, that the Thr 14-directed kinase is tightly membrane associated. Specifically, we have shown that a purified membrane fraction, in the absence of cytoplasm, can promote phosphorylation of cdc2 on both Thr 14 and Tyr 15. In contrast, the cytoplasm can phosphorylate cdc2 only on Tyr 15, suggesting the existence of at least two distinctly localized subpopulations of cdc2 Tyr 15-directed kinases. The membrane-associated Tyr 15 and Thr 14 kinase activities behaved similarly during salt or detergent extraction and were similarly regulated during the cell cycle and by the checkpoint machinery that delays mitosis while DNA is being replicated. This suggests the possibility that a dual-specificity membrane-associated protein kinase may catalyze phosphorylation of both Tyr 15 and Thr 14.

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Salmonella in Australia: understanding and controlling infection

Microbiology Australia ◽

10.1071/ma17044 ◽

2017 ◽

Vol 38 (3) ◽

pp. 112

Author(s):

Joshua PM Newson

Keyword(s):

Host Cell ◽

Cell Biology ◽

Protein Translocation ◽

Cell Signalling ◽

Effector Proteins ◽

Host Cells ◽

Secretion Systems ◽

Significant Burden ◽

Systemic Infections ◽

Bacterial Effectors

The bacterium Salmonella causes a spectrum of foodborne diseases ranging from acute gastroenteritis to systemic infections, and represents a significant burden of disease globally. In Australia, Salmonella is frequently associated with outbreaks and is a leading cause of foodborne illness, which results in a significant medical and economic burden. Salmonella infection involves colonisation of the small intestine, where the bacteria invades host cells and establishes an intracellular infection. To survive within host cells, Salmonella employs type-three secretion systems to deliver bacterial effector proteins into the cytoplasm of host cells. These bacterial effectors seek out and modify specific host proteins, disrupting host processes such as cell signalling, intracellular trafficking, and programmed cell death. This strategy of impairing host cells allows Salmonella to establish a replicative niche within the cell, where they can replicate to high numbers before escaping to infect neighbouring cells, or be transmitted to new hosts. While the importance of effector protein translocation to infection is well established, our understanding of many effector proteins remains incomplete. Many Salmonella effectors have unknown function and unknown roles during infection. A greater understanding of how Salmonella manipulates host cells during infection will lead to improved strategies to prevent, control, and eliminate disease. Further, studying effector proteins can be a useful means for exploring host cell biology and elucidating the details of host cell signalling.

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