ORCID Profile
0000-0002-0767-6017
Current Organisation
University of Aberdeen
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Publisher: Public Library of Science (PLoS)
Date: 13-06-2013
Publisher: Springer Science and Business Media LLC
Date: 09-2009
DOI: 10.1038/NATURE08358
Abstract: Phytophthora infestans is the most destructive pathogen of potato and a model organism for the oomycetes, a distinct lineage of fungus-like eukaryotes that are related to organisms such as brown algae and diatoms. As the agent of the Irish potato famine in the mid-nineteenth century, P. infestans has had a tremendous effect on human history, resulting in famine and population displacement. To this day, it affects world agriculture by causing the most destructive disease of potato, the fourth largest food crop and a critical alternative to the major cereal crops for feeding the world's population. Current annual worldwide potato crop losses due to late blight are conservatively estimated at $6.7 billion. Management of this devastating pathogen is challenged by its remarkable speed of adaptation to control strategies such as genetically resistant cultivars. Here we report the sequence of the P. infestans genome, which at approximately 240 megabases (Mb) is by far the largest and most complex genome sequenced so far in the chromalveolates. Its expansion results from a proliferation of repetitive DNA accounting for approximately 74% of the genome. Comparison with two other Phytophthora genomes showed rapid turnover and extensive expansion of specific families of secreted disease effector proteins, including many genes that are induced during infection or are predicted to have activities that alter host physiology. These fast-evolving effector genes are localized to highly dynamic and expanded regions of the P. infestans genome. This probably plays a crucial part in the rapid adaptability of the pathogen to host plants and underpins its evolutionary potential.
Publisher: Wiley
Date: 03-05-2000
DOI: 10.1111/J.1469-8137.2011.03736.X
Abstract: • A detailed molecular understanding of how oomycete plant pathogens evade disease resistance is essential to inform the deployment of durable resistance (R) genes. • Map-based cloning, transient expression in planta, pathogen transformation and DNA sequence variation across erse isolates were used to identify and characterize PiAVR2 from potato late blight pathogen Phytophthora infestans. • PiAVR2 is an RXLR-EER effector that is up-regulated during infection, accumulates at the site of haustoria formation, and is recognized inside host cells by potato protein R2. Expression of PiAVR2 in a virulent P. infestans isolate conveys a gain-of-avirulence phenotype, indicating that this is a dominant gene triggering R2-dependent disease resistance. PiAVR2 presence/absence polymorphisms and differential transcription explain virulence on R2 plants. Isolates infecting R2 plants express PiAVR2-like, which evades recognition by R2. PiAVR2 and PiAVR2-like differ in 13 amino acids, eight of which are in the C-terminal effector domain one or more of these determines recognition by R2. Nevertheless, few polymorphisms were observed within each gene in pathogen isolates, suggesting limited selection pressure for change within PiAVR2 and PiAVR2-like. • Our results direct a search for R genes recognizing PiAVR2-like, which, deployed with R2, may exert strong selection pressure against the P. infestans population.
Publisher: The Royal Society
Date: 05-12-2016
Abstract: Oomycetes, or water moulds, are fungal-like organisms phylogenetically related to algae. They cause devastating diseases in both plants and animals. Here, we describe seven oomycete species that are emerging or re-emerging threats to agriculture, horticulture, aquaculture and natural ecosystems. They include the plant pathogens Phytophthora infestans , Phytophthora palmivora , Phytophthora ramorum , Plasmopara obducens , and the animal pathogens Aphanomyces invadans , Saprolegnia parasitica and Halioticida noduliformans . For each species, we describe its pathology, importance and impact, discuss why it is an emerging threat and briefly review current research activities. This article is part of the themed issue ‘Tackling emerging fungal threats to animal health, food security and ecosystem resilience’.
Publisher: Elsevier BV
Date: 11-2012
Publisher: American Society for Microbiology
Date: 11-2014
DOI: 10.1128/IAI.02196-14
Abstract: Saprolegnia parasitica is a freshwater oomycete that is capable of infecting several species of fin fish. Saprolegniosis, the disease caused by this microbe, has a substantial impact on Atlantic salmon aquaculture. No sustainable treatment against saprolegniosis is available, and little is known regarding the host response. In this study, we examined the immune response of Atlantic salmon to S. parasitica infection and to its cell wall carbohydrates. Saprolegnia triggers a strong inflammatory response in its host (i.e., induction of interleukin-1β 1 [IL-1β 1 ], IL-6, and tumor necrosis factor alpha), while severely suppressing the expression of genes associated with adaptive immunity in fish, through downregulation of T-helper cell cytokines, antigen presentation machinery, and immunoglobulins. Oomycete cell wall carbohydrates were recognized by fish leukocytes, triggering upregulation of genes involved in the inflammatory response, similar to what is observed during infection. Our data suggest that S. parasitica is capable of producing prostaglanding E 2 (PGE 2 ) in vitro , a metabolite not previously shown to be produced by oomycetes, and two proteins with homology to vertebrate enzymes known to play a role in prostaglandin biosynthesis have been identified in the oomycete genome. Exogenous PGE 2 was shown to increase the inflammatory response in fish leukocytes incubated with cell wall carbohydrates while suppressing genes involved in cellular immunity (gamma interferon [IFN-γ] and the IFN-γ-inducible protein [γ-IP]). Inhibition of S. parasitica zoospore germination and mycelial growth by two cyclooxygenase inhibitors (aspirin and indomethacin) also suggests that prostaglandins may be involved in oomycete development.
Publisher: Springer Science and Business Media LLC
Date: 02-2016
DOI: 10.1038/NCOMMS10470
Abstract: Plasmodium falciparum exports proteins into erythrocytes using the Plasmodium export element (PEXEL) motif, which is cleaved in the endoplasmic reticulum (ER) by plasmepsin V (PMV). A recent study reported that phosphatidylinositol-3-phosphate (PI(3)P) concentrated in the ER binds to PEXEL motifs and is required for export independent of PMV, and that PEXEL motifs are functionally interchangeable with RxLR motifs of oomycete effectors. Here we show that the PEXEL does not bind PI(3)P, and that this lipid is not concentrated in the ER. We find that RxLR motifs cannot mediate export in P. falciparum . Parasites expressing a mutated version of KAHRP, with the PEXEL motif repositioned near the signal sequence, prevented PMV cleavage. This mutant possessed the putative PI(3)P-binding residues but is not exported. Reinstatement of PEXEL to its original location restores processing by PMV and export. These results challenge the PI(3)P hypothesis and provide evidence that PEXEL position is conserved for co-translational processing and export.
Publisher: Informa UK Limited
Date: 03-08-2015
Publisher: Proceedings of the National Academy of Sciences
Date: 28-06-2010
Abstract: We describe a mechanosensitive (MS) channel that has mechanosensitive channel of miniconductance (MscM) activity, and displays unique properties with respect to gating. Mechanosensitive channels respond to membrane tension, are ubiquitous from bacteria to man, and exhibit a great ersity in structure and function. These channels protect Bacteria and Archaea against hypoosmotic shock and are critical determinants of shape in chloroplasts. Given the dominant roles played in bacteria by the mechanosensitive channel of small conductance (MscS) and the mechanosensitive channel of large conductance (MscL), the role of the multiple MS channel homologs observed in most organisms remains obscure. Here we demonstrate that a MscS homolog, YbdG, extends the range of hypoosmotic shock that Escherichia coli cells can survive, but its expression level is insufficient to protect against severe shocks. Overexpression of the YbdG protein provides complete protection. Transcription and translation of the ybdG gene are enhanced by osmotic stress consistent with a role for the protein in survival of hypoosmotic shock. Measurement of the conductance of the native channel by standard patch cl methods was not possible. However, a fully functional YbdG mutant channel, V229A, exhibits a conductance in membrane patches consistent with MscM activity. We find that MscM activities arise from more than one gene product because ybdG deletion mutants still exhibit an occasional MscM-like conductance. We propose that ybdG encodes a low-abundance MscM-type MS channel, which in cells relieves low levels of membrane tension, obviating the need to activate the major MS channels, MscS and MscL.
Publisher: Elsevier BV
Date: 07-2014
Publisher: American Society for Microbiology
Date: 2015
DOI: 10.1128/IAI.02821-14
Publisher: Oxford University Press (OUP)
Date: 03-2008
Abstract: Cellulose, the important structural compound of cell walls, provides strength and rigidity to cells of numerous organisms. Here, we functionally characterize four cellulose synthase genes (CesA) in the oomycete plant pathogen Phytophthora infestans, the causal agent of potato (Solanum tuberosum) late blight. Three members of this new protein family contain Pleckstrin homology domains and form a distinct phylogenetic group most closely related to the cellulose synthases of cyanobacteria. Expression of all four genes is coordinately upregulated during pre- and early infection stages of potato. Inhibition of cellulose synthesis by 2,6-dichlorobenzonitrile leads to a dramatic reduction in the number of normal germ tubes with appressoria, severe disruption of the cell wall in the preinfection structures, and a complete loss of pathogenicity. Silencing of the entire gene family in P. infestans with RNA interference leads to a similar disruption of the cell wall surrounding appressoria and an inability to form typical functional appressoria. In addition, the cellulose content of the cell walls of the silenced lines is & % lower than in the walls of the nonsilenced lines. Our data demonstrate that the isolated genes are involved in cellulose biosynthesis and that cellulose synthesis is essential for infection by P. infestans.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Pieter van West.