We describe an approach to bottom-up fabrication that allows integration of the functional diversity of proteins into designed three-dimensional structural frameworks. A set of custom staple proteins ...based on transcription activator-like effector proteins folds a double-stranded DNA template into a user-defined shape. Each staple protein is designed to recognize and closely link two distinct double-helical DNA sequences at separate positions on the template. We present design rules for constructing megadalton-scale DNA-protein hybrid shapes; introduce various structural motifs, such as custom curvature, corners, and vertices; and describe principles for creating multilayer DNA-protein objects with enhanced rigidity. We demonstrate self-assembly of our hybrid nanostructures in one-pot mixtures that include the genetic information for the designed proteins, the template DNA, RNA polymerase, ribosomes, and cofactors for transcription and translation.
Ralstonia solanacearum is a devastating bacterial phytopathogen with a broad host range. Ralstonia solanacearum injected effector proteins (Rips) are key to the successful invasion of host plants. We ...have characterized Brg11(hrpB‐regulated 11), the first identified member of a class of Rips with high sequence similarity to the transcription activator‐like (TAL) effectors of Xanthomonas spp., collectively termed RipTALs. Fluorescence microscopy of in planta expressed RipTALs showed nuclear localization. Domain swaps between Brg11 and Xanthomonas TAL effector (TALE) AvrBs3 (avirulence protein triggering Bs3 resistance) showed the functional interchangeability of DNA‐binding and transcriptional activation domains. PCR was used to determine the sequence of brg11 homologs from strains infecting phylogenetically diverse host plants. Brg11 localizes to the nucleus and activates promoters containing a matching effector‐binding element (EBE). Brg11 and homologs preferentially activate promoters containing EBEs with a 5′ terminal guanine, contrasting with the TALE preference for a 5′ thymine. Brg11 and other RipTALs probably promote disease through the transcriptional activation of host genes. Brg11 and the majority of homologs identified in this study were shown to activate similar or identical target sequences, in contrast to TALEs, which generally show highly diverse target preferences. This information provides new options for the engineering of plants resistant to R. solanacearum.
Phytopathogenic fungi secrete a large arsenal of effector molecules, including proteinaceous effectors, small RNAs, phytohormones and derivatives thereof. The pathogenicity of fungal pathogens is ...primarily determined by these effectors that are secreted into host cells to undermine innate immunity, as well as to facilitate the acquisition of nutrients for their in planta growth and proliferation. After conventional and non‐conventional secretion, fungal effectors are translocated into different subcellular compartments of the host cells to interfere with various biological processes. In extracellular spaces, apoplastic effectors cope with physical and chemical barriers to break the first line of plant defenses. Intracellular effectors target essential immune components on the plasma membrane, in the cytosol, including cytosolic organelles, and in the nucleus to suppress host immunity and reprogram host physiology, favoring pathogen colonization. In this review, we comprehensively summarize the recent advances in fungal effector biology, with a focus on the versatile virulence functions of fungal effectors in promoting pathogen infection and colonization. A perspective of future research on fungal effector biology is also discussed.
Phytopathogenic fungi secrete apoplastic and cytoplasmic effectors to interfere with various biological processes and reprogram host immunity. This comprehensively summarizes the recent advances on how these versatile fungal effectors target various plant immune components in different subcellular compartments to promote pathogen infection and colonization.
Over the past decade, tremendous progress has been made in plant pathology, broadening our understanding of how pathogens colonize their hosts. To manipulate host cell physiology and subvert plant ...immune responses, pathogens secrete an array of effector proteins. A coevolutionary arms-race drives the pathogen to constantly reinvent its effector repertoire to undermine plant immunity. In turn, hosts develop novel immune receptors to maintain effector recognition and mount defences. Understanding how effectors promote disease and how they are perceived by the plant’s defence network persist as major subjects in the study of plant–pathogen interactions. Here, we focus on recent advances (over roughly the last two years) in understanding structure/function relationships in effectors from bacteria and filamentous plant pathogens. Structure/function studies of bacterial effectors frequently uncover diverse catalytic activities, while structure-informed similarity searches have enabled cataloguing of filamentous pathogen effectors. We also suggest how such advances have informed the study of plant–pathogen interactions.
The Fin-Ray principle, inspired by the physiology of fish rays, represents the foundation of a large number of robotic devices. However, despite their popularity, there is not any ad-hoc theoretical ...model technique for the analysis of this family of fingers. This lack is the main motivation of the presented work, which provides the mathematical modeling, analysis, and prototyping of a closed-chain Fin-Ray finger. In this scenario, the contribution of this article is twofold. At one end, we provide a general discrete Cosserat approach for the modeling of closed-chain soft robots which shares the geometrical structure of the rigid robotics counterpart. On the other end, the approach is employed to explore the family of Fin-Ray effect fingers. Finally, an improved design, which is able to conform to contacting surfaces, while maintaining stiffness out of its grasping plane, is fabricated and its performances are compared to those of a previously proposed prototype.
Plant immune networks Ngou, Bruno Pok Man; Jones, Jonathan D.G.; Ding, Pingtao
Trends in plant science,
March 2022, 2022-03-00, 20220301, Letnik:
27, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Plants have both cell-surface and intracellular receptors to recognize diverse self- and non-self molecules. Cell-surface pattern recognition receptors (PRRs) recognize extracellular ...pathogen-/damage-derived molecules or apoplastic pathogen-derived effectors. Intracellular nucleotide-binding leucine-rich repeat proteins (NLRs) recognize pathogen effectors. Activation of both PRRs and NLRs elevates defense gene expression and accumulation of the phytohormone salicylic acid (SA), which results in SA-dependent transcriptional reprogramming. These receptors, together with their coreceptors, form networks to mediate downstream immune responses. In addition, cell-surface and intracellular immune systems are interdependent and function synergistically to provide robust resistance against pathogens. Here, we summarize the interactions between these immune systems and attempt to provide a holistic picture of plant immune networks. We highlight current challenges and discuss potential new research directions.
Plant immunity is activated by PAMPs, effectors, and further enhanced by elevated SA, which are mediated by PRRs, NLRs, and SA receptors (NPR proteins), respectively.PRRs, NLRs, and NPR proteins interact genetically to mediate immune signals and activate robust immune outputs.Models are being elaborated for the crosstalk between PRRs, NLRs, and SA signaling.Different immune systems interact with each other both locally and systemically.
SUMMARY
Plant bacterial pathogens usually cause diseases by secreting and translocating numerous virulence effectors into host cells and suppressing various host immunity pathways. It has been ...demonstrated that the extensive ubiquitin systems of host cells are frequently interfered with or hijacked by numerous pathogenic bacteria, through various strategies. Some type‐III secretion system (T3SS) effectors of plant pathogens have been demonstrated to impersonate the F‐box protein (FBP) component of the SKP1/CUL1/F‐box (SCF) E3 ubiquitin system for their own benefit. Although numerous putative eukaryotic‐like F‐box effectors have been screened for different bacterial pathogens by bioinformatics analyses, the targets of most F‐box effectors in host immune systems remain unknown. Here, we show that XopI, a putative F‐box effector of African Xoo (Xanthomonas oryzae pv. oryzae) strain BAI3, strongly inhibits the host’s OsNPR1‐dependent resistance to Xoo. The xopI knockout mutant displays lower virulence in Oryza sativa (rice) than BAI3. Mechanistically, we identify a thioredoxin protein, OsTrxh2, as an XopI‐interacting protein in rice. Although OsTrxh2 positively regulates rice immunity by catalyzing the dissociation of OsNPR1 into monomers in rice, the XopI effector serves as an F‐box adapter to form an OSK1–XopI–OsTrxh2 interaction complex, and further disrupts OsNPR1‐mediated resistance through proteasomal degradation of OsTrxh2. Our results indicate that XopI targets OsTrxh2 and further represses OsNPR1‐dependent signaling, thereby subverting systemic acquired resistance (SAR) immunity in rice.
Significance Statement
The XopI effector of African Xoo strain, BAI3, serves as an F‐box adapter to form an OSK1–XopI–OsTrxh2 interaction complex in rice cell cytoplasm, and further disrupts OsNPR1‐mediated resistance through the proteasomal degradation of OsTrxh2 in compatible BAI3–rice interactions. These data will greatly enrich our understanding of the molecular mechanisms controlling how pathogenic bacteria interfere with the host’s OsNPR1‐mediated SAR signaling pathway through impersonating and using host SCF machinery.
Protein glycosylation is the most common post-translational modification as more than 50% of all human proteins are glycosylated. Pathogenic bacteria glycosylation allows adhesion to host cells and ...manipulates eukaryotic functions. A variety of acceptor proteins in bacterial glycosylation was recently discovered. Especially NleB/SseKs type III effectors unexpectedly glycosylate a poor nucleophile arginine. Other pathogenic toxins modify the unusual tyrosine, as well as canonical serine/threonine residues. And a huge diversity is found in target proteins; Rho/Ras families, death domains and moreover themselves for autoglycosylation. However, in spite of this acceptor diversity, all their sugar donors are only UDP-Glc/-GlcNAc and structural alignments as liganded show their catalytic cores are geometrically conserved, where DRY and DXD motives and W residues equally position to hold the sugar donors and to π-π bind with a uridine ring, respectively. Therefore, bacterial glycosyltransferases have a key for carbohydrate research problems concerning the sugar donors and target proteins recognition.
Type III secretion system (T3SS) effectors are key virulence factors that underpin the infection strategy of many clinically important Gram-negative pathogens, including Salmonella enterica, Shigella ...spp., enteropathogenic and enterohemorrhagic Escherichia coli and their murine equivalent, Citrobacter rodentium. The cellular processes or proteins targeted by the effectors can be common to multiple pathogens or pathogen-specific. The main approach to understanding T3SS-mediated pathogenesis has been to determine the contribution of one effector at a time, with the aim of piecing together individual functions and unveiling infection mechanisms. However, in contrast to this prevailing approach, simultaneous deletion of multiple effectors revealed that they function as an interconnected network in vivo, uncovering effector codependency and context-dependent effector essentiality. This paradigm shift in T3SS biology is at the heart of this opinion article.
Type III secretion system (T3SS) effectors exhibit unique binding or enzymatic activities once injected into eukaryotic cells.With only a few exceptions, single effector gene deletions exhibit no in vivo colonization phenotypes.T3SS effectors can form robust intracellular signaling networks that tolerate significant contraction while maintaining virulence.Distinct functional subnetworks trigger vastly different immune responses and impact tissue tropism.Effectors and cytokines can exhibit context-dependent essentiality.Studying the roles of individual T3SS effectors in vivo should be done in the context of the entire effector network.
PDF
