scholarly journals Inactivation of the mitogen-activated protein kinase Mps1 from the rice blast fungus prevents penetration of host cells but allows activation of plant defense responses

1998 ◽  
Vol 95 (21) ◽  
pp. 12713-12718 ◽  
Author(s):  
J.-R. Xu ◽  
C. J. Staiger ◽  
J. E. Hamer
Keyword(s):  
Protein Kinase ◽  
Plant Defense ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
Defense Responses ◽  
Host Cells ◽  
Mitogen Activated Protein Kinase ◽  
Plant Defense Responses ◽  
Blast Fungus ◽  
Mitogen Activated Protein

scholarly journals MST12 Regulates Infectious Growth But Not Appressorium Formation in the Rice Blast Fungus Magnaporthe grisea

2002 ◽  
Vol 15 (3) ◽  
pp. 183-192 ◽  
Author(s):  
Gyungsoon Park ◽  
Chaoyang Xue ◽  
Li Zheng ◽  
Stephen Lam ◽  
Jin-Rong Xu
Keyword(s):  
Transcription Factor ◽  
Rice Blast ◽  
Magnaporthe Grisea ◽  
Rice Blast Fungus ◽  
Gene Replacement ◽  
Mitogen Activated Protein Kinase ◽  
Kinase Gene ◽  
Blast Fungus ◽  
Mitogen Activated Protein ◽  
Barley Leaves

In the rice blast fungus Magnaporthe grisea, a mitogen-activated protein kinase gene, PMK1, is known to regulate ap-pressorium formation and infectious hyphae growth. Since PMK1 is homologous to the FUS3 and KSS1 genes that regulate the transcription factor STE12 in yeast, we functionally characterized the STE12 homologue in M. grisea (MST12). A polymerase chain reaction-based approach was used to isolate the MST12 gene that is homologous to yeast STE12. Four mst12 deletion mutants were isolated by gene replacement. No obvious defect in vegetative growth, conidiation, or conidia germination was observed in mst12 mutants. However, mst12 mutants were nonpathogenic on rice and barley leaves. In contrast to pmk1 mutants that did not form appressoria, mst12 mutants produced typical dome-shaped and melanized appressoria. However, the ap-pressoria formed by mst12 mutants failed to penetrate onion epidermal cells. When inoculated through wound sites, mst12 mutants failed to cause spreading lesions and appeared to be defective in infectious growth. These data indicate that MST12 may function downstream of PMK1 to regulate genes involved in infectious hyphae growth. A transcription factor or factors other than MST12 must exist in M. grisea and function downstream from PMK1 for ap-pressorium formation.

scholarly journals Mitogen-activated protein kinases associated sites of tobacco REPRESSION OF SHOOT GROWTH regulates its localization in plant cells

2021 ◽  
Author(s):  
Luyao Wang ◽  
Ying Gui ◽  
Bingye Yang ◽  
Fangjie Si ◽  
Jianhua Guo ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Plant Defense ◽  
Shoot Growth ◽  
Leucine Zipper ◽  
Intracellular Localization ◽  
Phosphorylation Site ◽  
Feedback Regulation ◽  
Mitogen Activated Protein Kinase ◽  
Basic Leucine Zipper ◽  
Mitogen Activated Protein

Plant defense and growth rely on multiple transcriptional factors (TFs). REPRESSION OF SHOOT GROWTH (RSG) is known as one of the important TFs in tobacco (Nicotiana tabacum) with a basic leucine zipper domain. RSG was involved in plant gibberellin feedback regulation by inducing the expression of key genes. The tobacco calcium-dependent protein kinase, CDPK1 was reported to interact with RSG and manipulate its intracellular localization by phosphorylating Ser-114 of RSG. Here, we identified tobacco mitogen-activated protein kinase 3 (NtMPK3) as a RSG interacted protein kinase. Mutation of predicted MAPK-associated phosphorylation site of RSG (Thr-30, Ser-74 and Thr-135) significantly altered the intracellular localization of NtMPK3-RSG interaction complex. Nuclear transport of RSG and its amino acids mutants (T30A and S74A) were observed after treated with plant defense elicitor peptide flg22 in 5 min, while the two mutated RSG swiftly relocalized in tobacco cytoplasm in 30 min. Moreover, triple points mutation of RSG (T30A/S74A/T135A) mimics constant unphosphorylated status, and predominantly localized in tobacco cytoplasm. RSG (T30A/S74A/T135A) showed no relocalization effect under the treatments of either flg22, B. cereus AR156 or GA3, and was impaired in its role as TFs. Our results suggest that MAPK associated phosphorylation sites of RSG regulate its localization in tobacco and constant unphosphorylation of RSG in Thr-30, Ser-74 and Thr-135 keeps RSG predominantly localized in cytoplasm.

scholarly journals Identification of Msp1-Induced Signaling Components in Rice Leaves by Integrated Proteomic and Phosphoproteomic Analysis

2019 ◽  
Vol 20 (17) ◽  
pp. 4135 ◽  
Author(s):  
Ravi Gupta ◽  
Cheol Woo Min ◽  
Yu-Jin Kim ◽  
Sun Tae Kim
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase ◽  
Defense Responses ◽  
Mitogen Activated Protein Kinase ◽  
Calcium Dependent ◽  
Molecular Pattern ◽  
Mitogen Activated Protein ◽  
Dependent Protein ◽  
Rice Leaves ◽  
Respiratory Burst Oxidase

MSP1 is a Magnaporthe oryzae secreted protein that elicits defense responses in rice. However, the molecular mechanism of MSP1 action is largely elusive. Moreover, it is yet to be established whether MSP1 functions as a pathogen-associated molecular pattern (PAMP) or an effector. Here, we employed a TMT-based quantitative proteomic analysis of cytosolic as well as plasma membrane proteins to decipher the MSP1 induced signaling in rice. This approach led to the identification of 6691 proteins, of which 3049 were identified in the plasma membrane (PM), while 3642 were identified in the cytosolic fraction. A parallel phosphoproteome analysis led to the identification of 1906 phosphopeptides, while the integration of proteome and phosphoproteome data showed activation of proteins related to the proteolysis, jasmonic acid biosynthesis, redox metabolism, and MAP kinase signaling pathways in response to MSP1 treatment. Further, MSP1 induced phosphorylation of some of the key proteins including respiratory burst oxidase homologue-D (RBOHD), mitogen-activated protein kinase kinase kinase-1 (MEKK1), mitogen-activated protein kinase-3/6 (MPK3/6), calcium-dependent protein kinase (CDPK) and calmodulin (CaM) suggest activation of PAMP-triggered immunity (PTI) in response to MSP1 treatment. In essence, our results further support the functioning of MSP1 as a PAMP and provide an overview of the MSP1 induced signaling in rice leaves.

Magnaporthe Oryzae Chloroplast-Targeting Endo-β-1,4-Xylanase I MoXYL1A Regulates Conidiation, Appressorium Maturation and Virulence of the Rice Blast Fungus

2021 ◽  
Author(s):  
Ammarah Shabbir ◽  
Wajjiha Batool ◽  
Yu Dan ◽  
Lili Lin ◽  
An Anquoli ◽  
...  
Keyword(s):  
Rice Blast ◽  
Extracellular Enzymes ◽  
Rice Blast Fungus ◽  
Effector Proteins ◽  
Host Cells ◽  
Primary Cell Wall ◽  
In Planta ◽  
Critical Function ◽  
Chloroplast Targeting ◽  
Blast Fungus

Abstract Endo-β-1,4-Xylanases are a group of extracellular enzymes that catalyze the hydrolysis of xylan, a principal constituent of the plant primary cell wall. The contribution of Endo-β-1,4-Xylanase I to both physiology and pathogenesis of the rice blast fungus M. oryzae is unknown. Here, we characterized the biological function of two endoxylanase I (MoXYL1A and MoXYL1B) genes in the development of M. oryzae using targeted gene deletion, biochemical analysis, and fluorescence microscopy. Phenotypic analysis of ∆Moxyl1A strains showed that MoXYL1A is required for the full virulence of M. oryzae but is dispensable for the vegetative growth of the rice blast fungus. MoXYL1B, in contrast, did not have a clear role in the infectious cycle but has a critical function in asexual reproduction of the fungus. The double deletion mutant was severely impaired in pathogenicity and virulence as well as asexual development. We found that MoXYL1A deletion compromised appressorium morphogenesis and function, leading to failure to penetrate host cells. Fluorescently tagged MoXYL1A and MoXYL1B displayed cytoplasmic localization in M. oryzae, while analysis of MoXYL1A-GFP and MoXYL1B-GFP in-planta revealed translocation and accumulation of these effector proteins into host cells. Meanwhile, sequence feature analysis showed that MoXYL1A possesses a transient chloroplast targeting signal peptide, and results from an Agrobacterium infiltration assay confirmed co-localization of MoXYL1A-GFP with ChCPN10C-RFP in the chloroplasts of host cells. MoXYL1B, accumulated to the cytoplasm of the host. Taken together, we conclude that MoXYL1A is a secreted effector protein that likely promotes the virulence of M. oryzae by interfering in the proper functioning of the host chloroplast, while the related xylanase MoXYL1B does not have a major role in virulence of M. oryzae.

Manipulation of host signalling pathways by anthrax toxins

2007 ◽  
Vol 402 (3) ◽  
pp. 405-417 ◽  
Author(s):  
Benjamin E. Turk
Keyword(s):  
Protein Kinase ◽  
Pathogenic Bacteria ◽  
Protective Antigen ◽  
Lethal Factor ◽  
Cell Types ◽  
Host Cells ◽  
Mitogen Activated Protein Kinase ◽  
Signalling Pathways ◽  
Common Strategy ◽  
Mitogen Activated Protein

Infectious microbes face an unwelcoming environment in their mammalian hosts, which have evolved elaborate multicelluar systems for recognition and elimination of invading pathogens. A common strategy used by pathogenic bacteria to establish infection is to secrete protein factors that block intracellular signalling pathways essential for host defence. Some of these proteins also act as toxins, directly causing pathology associated with disease. Bacillus anthracis, the bacterium that causes anthrax, secretes two plasmid-encoded enzymes, LF (lethal factor) and EF (oedema factor), that are delivered into host cells by a third bacterial protein, PA (protective antigen). The two toxins act on a variety of cell types, disabling the immune system and inevitably killing the host. LF is an extraordinarily selective metalloproteinase that site-specifically cleaves MKKs (mitogen-activated protein kinase kinases). Cleavage of MKKs by LF prevents them from activating their downstream MAPK (mitogen-activated protein kinase) substrates by disrupting a critical docking interaction. Blockade of MAPK signalling functionally impairs cells of both the innate and adaptive immune systems and induces cell death in macrophages. EF is an adenylate cyclase that is activated by calmodulin through a non-canonical mechanism. EF causes sustained and potent activation of host cAMP-dependent signalling pathways, which disables phagocytes. Here I review recent progress in elucidating the mechanisms by which LF and EF influence host signalling and thereby contribute to disease.

scholarly journals Lipoarabinomannan-Induced Cell Signaling Involves Ceramide and Mitogen-Activated Protein Kinase

2002 ◽  
Vol 9 (6) ◽  
pp. 1175-1182 ◽  
Author(s):  
Madhumita Sirkar ◽  
Subrata Majumdar
Keyword(s):  
Protein Kinase ◽  
Cell Survival ◽  
Tyrosine Phosphorylation ◽  
Mononuclear Cells ◽  
Pi3 Kinase ◽  
Host Cells ◽  
Mitogen Activated Protein Kinase ◽  
Ceramide Level ◽  
Morphological Studies ◽  
Mitogen Activated Protein

ABSTRACT Lipoarabinomannan (LAM) is a major cell wall-associated lipoglycan, produced in large amounts (15 mg/g of bacteria) in different species of mycobacteria. Our laboratory has previously reported that LAM from Mycobacterium smegmatis exerts its cytotoxic activity via inhibition of protein kinase C, a key signaling molecule inside the mononuclear cells (S. Ghosh, S. Pal, S. Das, S. K. Dasgupta, and S. Majumdar, FEMS Immunol. Med. Microbiol. 21:181-188, 1998). In this study we report that LAM from Mycobacterium tuberculosis induces a signal transduction pathway in favor of survivability of the host cells via the generation of ceramide, a novel second messenger. The endogenous ceramide level in mononuclear cells was found to be enhanced during LAM treatment. The effects of LAM on protein tyrosine phosphorylation in human peripheral blood mononuclear cells were examined. LAM enhanced the tyrosine phosphorylation of p42 mitogen-activated protein kinase and phosphoinositol 3-kinase (PI3 kinase) and dephosphorylation of stress-activated protein kinase. LAM-induced phosphorylation of p42 (extracellular signal-regulated kinase 2) was further enhanced by wortmannin, a PI3 kinase inhibitor. To examine whether these effects are due to elevation of endogenous ceramide, we exposed the cells to cell-permeative C2-ceramide exogenously and studied the activities of different protein kinases. Fluorescence-activated cell sorter analysis and morphological studies showed that LAM induces cell survival. Therefore, these results suggest the ability of LAM to induce ceramide in the altered signaling pathway and help in cell survival.

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