Lysin Motif (LysM) Proteins: Interlinking Manipulation of Plant Immunity and Fungi

The proteins with lysin motif (LysM) are carbohydrate-binding protein modules that play a critical role in the host-pathogen interactions. The plant LysM proteins mostly function as pattern recognition receptors (PRRs) that sense chitin to induce the plant’s immunity. In contrast, fungal LysM blocks chitin sensing or signaling to inhibit chitin-induced host immunity. In this review, we provide historical perspectives on plant and fungal LysMs to demonstrate how these proteins are involved in the regulation of plant’s immune response by microbes. Plants employ LysM proteins to recognize fungal chitins that are then degraded by plant chitinases to induce immunity. In contrast, fungal pathogens recruit LysM proteins to protect their cell wall from hydrolysis by plant chitinase to prevent activation of chitin-induced immunity. Uncovering this coevolutionary arms race in which LysM plays a pivotal role in manipulating facilitates a greater understanding of the mechanisms governing plant-fungus interactions.

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Molecular Mechanisms of Chitosan Interactions with Fungi and Plants

International Journal of Molecular Sciences ◽

10.3390/ijms20020332 ◽

2019 ◽

Vol 20 (2) ◽

pp. 332 ◽

Cited By ~ 23

Author(s):

Federico Lopez-Moya ◽

Marta Suarez-Fernandez ◽

Luis Lopez-Llorca

Keyword(s):

Cell Walls ◽

Fungal Pathogens ◽

Molecular Mechanisms ◽

Plant Immunity ◽

Fungal Colonization ◽

Fungal Cell ◽

Physiological Basis ◽

Mammalian Cell Lines ◽

Root Interactions ◽

Plant Chitinases

Chitosan is a versatile compound with multiple biotechnological applications. This polymer inhibits clinically important human fungal pathogens under the same carbon and nitrogen status as in blood. Chitosan permeabilises their high-fluidity plasma membrane and increases production of intracellular oxygen species (ROS). Conversely, chitosan is compatible with mammalian cell lines as well as with biocontrol fungi (BCF). BCF resistant to chitosan have low-fluidity membranes and high glucan/chitin ratios in their cell walls. Recent studies illustrate molecular and physiological basis of chitosan-root interactions. Chitosan induces auxin accumulation in Arabidopsis roots. This polymer causes overexpression of tryptophan-dependent auxin biosynthesis pathway. It also blocks auxin translocation in roots. Chitosan is a plant defense modulator. Endophytes and fungal pathogens evade plant immunity converting chitin into chitosan. LysM effectors shield chitin and protect fungal cell walls from plant chitinases. These enzymes together with fungal chitin deacetylases, chitosanases and effectors play determinant roles during fungal colonization of plants. This review describes chitosan mode of action (cell and gene targets) in fungi and plants. This knowledge will help to develop chitosan for agrobiotechnological and medical applications.

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Chitin-Binding Protein of Verticillium nonalfalfae Disguises Fungus from Plant Chitinases and Suppresses Chitin-Triggered Host Immunity

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-03-19-0079-r ◽

2019 ◽

Vol 32 (10) ◽

pp. 1378-1390 ◽

Cited By ~ 8

Author(s):

Helena Volk ◽

Kristina Marton ◽

Marko Flajšman ◽

Sebastjan Radišek ◽

Hui Tian ◽

...

Keyword(s):

Fungal Infections ◽

Binding Protein ◽

Host Immunity ◽

Binding Motif ◽

Carbohydrate Binding ◽

Suspension Cells ◽

Fungal Cell ◽

Verticillium Nonalfalfae ◽

Chitin Binding Protein ◽

Plant Chitinases

During fungal infections, plant cells secrete chitinases, which digest chitin in the fungal cell walls. The recognition of released chitin oligomers via lysin motif (LysM)-containing immune host receptors results in the activation of defense signaling pathways. We report here that Verticillium nonalfalfae, a hemibiotrophic xylem-invading fungus, prevents these digestion and recognition processes by secreting a carbohydrate-binding motif 18 (CBM18)-chitin-binding protein, VnaChtBP, which is transcriptionally activated specifically during the parasitic life stages. VnaChtBP is encoded by the Vna8.213 gene, which is highly conserved within the species, suggesting high evolutionary stability and importance for the fungal lifestyle. In a pathogenicity assay, however, Vna8.213 knockout mutants exhibited wilting symptoms similar to the wild-type fungus, suggesting that Vna8.213 activity is functionally redundant during fungal infection of hop. In a binding assay, recombinant VnaChtBP bound chitin and chitin oligomers in vitro with submicromolar affinity and protected fungal hyphae from degradation by plant chitinases. Moreover, the chitin-triggered production of reactive oxygen species from hop suspension cells was abolished in the presence of VnaChtBP, indicating that VnaChtBP also acts as a suppressor of chitin-triggered immunity. Using a yeast-two-hybrid assay, circular dichroism, homology modeling, and molecular docking, we demonstrated that VnaChtBP forms dimers in the absence of ligands and that this interaction is stabilized by the binding of chitin hexamers with a similar preference in the two binding sites. Our data suggest that, in addition to chitin-binding LysM (CBM50) and Avr4 (CBM14) fungal effectors, structurally unrelated CBM18 effectors have convergently evolved to prevent hydrolysis of the fungal cell wall against plant chitinases and to interfere with chitin-triggered host immunity.

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Microglia and Astrocyte Activation by Toll-Like Receptor Ligands: Modulation by PPAR-γAgonists

PPAR Research ◽

10.1155/2008/453120 ◽

2008 ◽

Vol 2008 ◽

pp. 1-15 ◽

Cited By ~ 52

Author(s):

Catherine Gurley ◽

Jessica Nichols ◽

Shuliang Liu ◽

Nirmal K. Phulwani ◽

Nilufer Esen ◽

...

Keyword(s):

Tissue Damage ◽

Critical Role ◽

Host Immunity ◽

Toll Like Receptor ◽

Primary Microglia ◽

Tissue Destruction ◽

Receptor Ligands ◽

Astrocyte Activation ◽

Comprehensive Survey ◽

Ccl2 Production

Microglia and astrocytes express numerous members of the Toll-like receptor (TLR) family that are pivotal for recognizing conserved microbial motifs expressed by a wide array of pathogens. Despite the critical role for TLRs in pathogen recognition, when dysregulated these pathways can also exacerbate CNS tissue destruction. Therefore, a critical balance must be achieved to elicit sufficient immunity to combat CNS infectious insults and down-regulate these responses to avoid pathological tissue damage. We performed a comprehensive survey on the efficacy of various PPAR-γagonists to modulate proinflammatory mediator release from primary microglia and astrocytes in response to numerous TLR ligands relevant to CNS infectious diseases. The results demonstrated differential abilities of select PPAR-γagonists to modulate glial activation. For example, 15d-PGJ2and pioglitazone were both effective at reducing IL-12 p40 release by TLR ligand-activated glia, whereas CXCL2 expression was either augmented or inhibited by 15d-PGJ2, effects that were dependent on the TLR ligand examined. Pioglitazone and troglitazone demonstrated opposing actions on microglial CCL2 production that were TLR ligand-dependent. Collectively, this information may be exploited to modulate the host immune response during CNS infections to maximize host immunity while minimizing inappropriate bystander tissue damage that is often characteristic of such diseases.

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Cysteine protease RD21A regulated by E3 ligase SINAT4 is required for drought-induced resistance to Pseudomonas syringae in Arabidopsis

Journal of Experimental Botany ◽

10.1093/jxb/eraa255 ◽

2020 ◽

Vol 71 (18) ◽

pp. 5562-5576

Author(s):

Yi Liu ◽

Kunru Wang ◽

Qiang Cheng ◽

Danyu Kong ◽

Xunzhong Zhang ◽

...

Keyword(s):

Pseudomonas Syringae ◽

Cysteine Protease ◽

Plant Immunity ◽

Stomatal Closure ◽

Bacterial Pathogen ◽

E3 Ligase ◽

Biotic Stresses ◽

Ubiquitin E3 Ligase ◽

Induced Immunity

Abstract Plants can be simultaneously exposed to multiple stresses. The interplay of abiotic and biotic stresses may result in synergistic or antagonistic effects on plant development and health. Temporary drought stress can stimulate plant immunity; however, the molecular mechanism of drought-induced immunity is largely unknown. In this study, we demonstrate that cysteine protease RD21A is required for drought-induced immunity. Temporarily drought-treated wild-type Arabidopsis plants became more sensitive to the bacterial pathogen-associated molecular pattern flg22, triggering stomatal closure, which resulted in increased resistance to Pseudomonas syringae pv. tomato DC3000 (Pst-DC3000). Knocking out rd21a inhibited flg22-triggered stomatal closure and compromised the drought-induced immunity. Ubiquitin E3 ligase SINAT4 interacted with RD21A and promoted its degradation in vivo. The overexpression of SINAT4 also consistently compromised the drought-induced immunity to Pst-DC3000. A bacterial type III effector, AvrRxo1, interacted with both SINAT4 and RD21A, enhancing SINAT4 activity and promoting the degradation of RD21A in vivo. Therefore, RD21A could be a positive regulator of drought-induced immunity, which could be targeted by pathogen virulence effectors during pathogenesis.

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Regulation and Functions of ROP GTPases in Plant–Microbe Interactions

Cells ◽

10.3390/cells9092016 ◽

2020 ◽

Vol 9 (9) ◽

pp. 2016

Author(s):

Stefan Engelhardt ◽

Adriana Trutzenberg ◽

Ralph Hückelhoven

Keyword(s):

Cell Invasion ◽

Rho Gtpases ◽

Fungal Pathogens ◽

Plant Immunity ◽

Pathogen Resistance ◽

Research Field ◽

Rho Proteins ◽

Downstream Signaling ◽

Microbe Interactions ◽

Developmental Reprogramming

Rho proteins of plants (ROPs) form a specific clade of Rho GTPases, which are involved in either plant immunity or susceptibility to diseases. They are intensively studied in grass host plants, in which ROPs are signaling hubs downstream of both cell surface immune receptor kinases and intracellular nucleotide-binding leucine-rich repeat receptors, which activate major branches of plant immune signaling. Additionally, invasive fungal pathogens may co-opt the function of ROPs for manipulation of the cytoskeleton, cell invasion and host cell developmental reprogramming, which promote pathogenic colonization. Strikingly, mammalian bacterial pathogens also initiate both effector-triggered susceptibility for cell invasion and effector-triggered immunity via Rho GTPases. In this review, we summarize central concepts of Rho signaling in disease and immunity of plants and briefly compare them to important findings in the mammalian research field. We focus on Rho activation, downstream signaling and cellular reorganization under control of Rho proteins involved in disease progression and pathogen resistance.

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Designed DNA-Encoded IL-36 Gamma Acts as a Potent Molecular Adjuvant Enhancing Zika Synthetic DNA Vaccine-Induced Immunity and Protection in a Lethal Challenge Model

Vaccines ◽

10.3390/vaccines7020042 ◽

2019 ◽

Vol 7 (2) ◽

pp. 42 ◽

Cited By ~ 3

Author(s):

Lumena Louis ◽

Megan C. Wise ◽

Hyeree Choi ◽

Daniel O. Villarreal ◽

Kar Muthumani ◽

...

Keyword(s):

Dna Vaccine ◽

Critical Role ◽

Lethal Challenge ◽

Synthetic Dna ◽

Molecular Adjuvant ◽

Immunodeficiency Virus ◽

Suboptimal Dose ◽

Dose Sparing ◽

Molecular Adjuvants ◽

Induced Immunity

Identification of novel molecular adjuvants which can boost and enhance vaccine-mediated immunity and provide dose-sparing potential against complex infectious diseases and for immunotherapy in cancer is likely to play a critical role in the next generation of vaccines. Given the number of challenging targets for which no or only partial vaccine options exist, adjuvants that can address some of these concerns are in high demand. Here, we report that a designed truncated Interleukin-36 gamma (IL-36 gamma) encoded plasmid can act as a potent adjuvant for several DNA-encoded vaccine targets including human immunodeficiency virus (HIV), influenza, and Zika in immunization models. We further show that the truncated IL-36 gamma (opt-36γt) plasmid provides improved dose sparing as it boosts immunity to a suboptimal dose of a Zika DNA vaccine, resulting in potent protection against a lethal Zika challenge.

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Evolutionary and structural analysis of SARS-CoV-2 specific evasion of host immunity

Genes and Immunity ◽

10.1038/s41435-020-00120-6 ◽

2020 ◽

Vol 21 (6-8) ◽

pp. 409-419

Author(s):

Irfan Hussain ◽

Nashaiman Pervaiz ◽

Abbas Khan ◽

Shoaib Saleem ◽

Huma Shireen ◽

...

Keyword(s):

Immune Responses ◽

Nonstructural Protein ◽

Critical Role ◽

Clinical Manifestations ◽

Host Immunity ◽

Innate Immune ◽

Host Immune System ◽

Innate Immune Responses ◽

In Vivo Models

AbstractThe outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spreading fast worldwide. There is a pressing need to understand how the virus counteracts host innate immune responses. Deleterious clinical manifestations of coronaviruses have been associated with virus-induced direct dysregulation of innate immune responses occurring via viral macrodomains located within nonstructural protein-3 (Nsp3). However, no substantial information is available concerning the relationship of macrodomains to the unusually high pathogenicity of SARS-CoV-2. Here, we show that structural evolution of macrodomains may impart a critical role to the unique pathogenicity of SARS-CoV-2. Using sequence, structural, and phylogenetic analysis, we identify a specific set of historical substitutions that recapitulate the evolution of the macrodomains that counteract host immune response. These evolutionary substitutions may alter and reposition the secondary structural elements to create new intra-protein contacts and, thereby, may enhance the ability of SARS-CoV-2 to inhibit host immunity. Further, we find that the unusual virulence of this virus is potentially the consequence of Darwinian selection‐driven epistasis in protein evolution. Our findings warrant further characterization of macrodomain-specific evolutionary substitutions in in vitro and in vivo models to determine their inhibitory effects on the host immune system.

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MiMIF-2 Effector of Meloidogyne incognita Exhibited Enzyme Activities and Potential Roles in Plant Salicylic Acid Synthesis

International Journal of Molecular Sciences ◽

10.3390/ijms21103507 ◽

2020 ◽

Vol 21 (10) ◽

pp. 3507

Author(s):

Jianlong Zhao ◽

Zhenchuan Mao ◽

Qinghua Sun ◽

Qian Liu ◽

Heng Jian ◽

...

Keyword(s):

Salicylic Acid ◽

Transcriptome Analysis ◽

Meloidogyne Incognita ◽

Plant Immunity ◽

Acid Synthesis ◽

Host Immunity ◽

Parasitic Nematodes ◽

Marker Genes ◽

Rna Seq ◽

Shock Proteins

Plant-parasitic nematodes secrete a series of effectors to promote parasitism by modulating host immunity, but the detailed molecular mechanism is ambiguous. Animal parasites secrete macrophage migration inhibitory factor (MIF)-like proteins for evasion of host immune systems, in which their biochemical activities play essential roles. Previous research demonstrated that MiMIF-2 effector was secreted by Meloidogyne incognita and modulated host immunity by interacting with annexins. In this study, we show that MiMIF-2 had tautomerase activity and protected nematodes against H2O2 damage. MiMIF-2 expression not only decreased the amount of H2O2 generation during nematode infection in Arabidopsis, but also suppressed Bax-induced cell death by inhibiting reactive oxygen species burst in Nicotiana benthamiana. Further, RNA-seq transcriptome analysis and RT-qPCR showed that the expression of some heat-shock proteins was down regulated in MiMIF-2 transgenic Arabidopsis. After treatment with flg22, RNA-seq transcriptome analysis indicated that the differentially expressed genes in MiMIF-2 expressing Arabidopsis were pointed to plant hormone signal transduction, compound metabolism and plant defense. RT-qPCR and metabolomic results confirmed that salicylic acid (SA) related marker genes and SA content were significantly decreased. Our results provide a comprehensive understanding of how MiMIF-2 modulates plant immunity and broaden knowledge of the intricate relationship between M. incognita and host plants.

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A Verticillium dahliae Extracellular Cutinase Modulates Plant Immune Responses

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-06-17-0136-r ◽

2018 ◽

Vol 31 (2) ◽

pp. 260-273 ◽

Cited By ~ 12

Author(s):

Yue-Jing Gui ◽

Wen-Qi Zhang ◽

Dan-Dan Zhang ◽

Lei Zhou ◽

Dylan P. G. Short ◽

...

Keyword(s):

Cell Death ◽

Plant Defense ◽

Verticillium Dahliae ◽

Fungal Pathogens ◽

Sequence Divergence ◽

Defense Responses ◽

Carbohydrate Binding ◽

Dependent Manner ◽

Virus Induced Gene Silencing ◽

Plant Defense Responses

Cutinases have been implicated as important enzymes during the process of fungal infection of aerial plant organs. The function of cutinases in the disease cycle of fungal pathogens that invade plants through the roots has been less studied. Here, functional analysis of 13 cutinase (carbohydrate esterase family 5 domain–containing) genes (VdCUTs) in the highly virulent vascular wilt pathogen Verticillium dahliae Vd991 was performed. Significant sequence divergence in cutinase family members was observed in the genome of V. dahliae Vd991. Functional analyses demonstrated that only VdCUT11, as purified protein, induced cell death and triggered defense responses in Nicotiana benthamiana, cotton, and tomato plants. Virus-induced gene silencing showed that VdCUT11 induces plant defense responses in Nicotiana benthamania in a BAK1 and SOBIR-dependent manner. Furthermore, coinfiltration assays revealed that the carbohydrate-binding module family 1 protein (VdCBM1) suppressed VdCUT11-induced cell death and other defense responses in N. benthamiana. Targeted deletion of VdCUT11 in V. dahliae significantly compromised virulence on cotton plants. The cutinase VdCUT11 is an important secreted enzyme and virulence factor that elicits plant defense responses in the absence of VdCBM1.

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Isolation and Characterization of Cryptococcus neoformans Spores Reveal a Critical Role for Capsule Biosynthesis Genes in Spore Biogenesis

Eukaryotic Cell ◽

10.1128/ec.00352-08 ◽

2009 ◽

Vol 8 (4) ◽

pp. 595-605 ◽

Cited By ~ 60

Author(s):

Michael R. Botts ◽

Steven S. Giles ◽

Marcellene A. Gates ◽

Thomas R. Kozel ◽

Christina M. Hull

Keyword(s):

Cryptococcus Neoformans ◽

Fungal Pathogens ◽

Critical Role ◽

Spore Formation ◽

Yeast Cells ◽

Isolation And Characterization ◽

Specific Configuration ◽

First Time

ABSTRACT Spores are essential particles for the survival of many organisms, both prokaryotic and eukaryotic. Among the eukaryotes, fungi have developed spores with superior resistance and dispersal properties. For the human fungal pathogens, however, relatively little is known about the role that spores play in dispersal and infection. Here we present the purification and characterization of spores from the environmental fungus Cryptococcus neoformans. For the first time, we purified spores to homogeneity and assessed their morphological, stress resistance, and surface properties. We found that spores are morphologically distinct from yeast cells and are covered with a thick spore coat. Spores are also more resistant to environmental stresses than yeast cells and display a spore-specific configuration of polysaccharides on their surfaces. Surprisingly, we found that the surface of the spore reacts with antibodies to the polysaccharide glucuronoxylomannan, the most abundant component of the polysaccharide capsule required for C. neoformans virulence. We explored the role of capsule polysaccharide in spore development by assessing spore formation in a series of acapsular strains and determined that capsule biosynthesis genes are required for proper sexual development and normal spore formation. Our findings suggest that C. neoformans spores may have an adapted cell surface that facilitates persistence in harsh environments and ultimately allows them to infect mammalian hosts.

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