Extracellular peptidases of the cereal pathogen Fusarium graminearum

Lowe, Russell; McCorkelle, Owen C.; Bleackley, Mark R.; Collins, Christine; Faou, Pierre; Mathivanan, Suresh; Anderson, Marilyn A.

doi:10.3389/fpls.2015.00962

Cited by 44 publications

(39 citation statements)

References 52 publications

(48 reference statements)

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“…Purified recombinant Av-DHDPS and Av-DHDPR were subjected to trypsin digestion and tandem mass spectrometry (MS/MS) sequencing using a Thermo Scientific LTQ Orbitrap Elite ETD Mass Spectrometer as previously reported4445.…”

Section: Methodsmentioning

confidence: 99%

Structure and Function of Cyanobacterial DHDPS and DHDPR

Christensen

Costa

Faou

et al. 2016

Sci Rep

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Lysine biosynthesis in bacteria and plants commences with a condensation reaction catalysed by dihydrodipicolinate synthase (DHDPS) followed by a reduction reaction catalysed by dihydrodipicolinate reductase (DHDPR). Interestingly, both DHDPS and DHDPR exist as different oligomeric forms in bacteria and plants. DHDPS is primarily a homotetramer in all species, but the architecture of the tetramer differs across kingdoms. DHDPR also exists as a tetramer in bacteria, but has recently been reported to be dimeric in plants. This study aimed to characterise for the first time the structure and function of DHDPS and DHDPR from cyanobacteria, which is an evolutionary important phylum that evolved at the divergence point between bacteria and plants. We cloned, expressed and purified DHDPS and DHDPR from the cyanobacterium Anabaena variabilis. The recombinant enzymes were shown to be folded by circular dichroism spectroscopy, enzymatically active employing the quantitative DHDPS-DHDPR coupled assay, and form tetramers in solution using analytical ultracentrifugation. Crystal structures of DHDPS and DHDPR from A. variabilis were determined at 1.92 Å and 2.83 Å, respectively, and show that both enzymes adopt the canonical bacterial tetrameric architecture. These studies indicate that the quaternary structure of bacterial and plant DHDPS and DHDPR diverged after cyanobacteria evolved.

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Section: Methodsmentioning

confidence: 99%

Structure and Function of Cyanobacterial DHDPS and DHDPR

Christensen

Costa

Faou

et al. 2016

Sci Rep

Self Cite

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“…Necrotrophy is characterized by increased fungal biomass as well as expression of plant cell wall degrading enzymes (CWDEs) and secondary metabolites to induce host cell death (Laluk and Mengiste, 2010;Palma-Guerrero et al, 2017). Peptidases secreted by fungal pathogens degrade host proteins to provide the invading fungus with cellular energy as well as substrates for growth, cell wall remodeling, protein synthesis, and nucleic acids (Lowe et al, 2015). Plant pathogens secrete CWDEs to aid in host penetration and to invasively colonize the host (Choi et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Time-Course RNAseq Reveals Exserohilum turcicum Effectors and Pathogenicity Determinants

2020

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Exserohilum turcicum (sexual stage Setosphaeria turcica) is the hemibiotrophic causal agent of northern leaf blight of maize and sorghum. This study aimed to identify the genes involved in host colonization during the biotrophic and necrotrophic phases of infection. It also aimed to identify race-specific differences in gene expression. RNAseq of maize seedlings inoculated with a race 13N or 23N E. turcicum isolate was conducted before inoculation and at 2, 5, 7, and 13 days post-inoculation (dpi). Biological replicates were pooled per time point for each race and sequenced. A bioinformatics pipeline was used to identify candidate effectors, and expression was validated for selected candidates. Fungal biomass was positively correlated with the percentages of E. turcicum reads mapped, which were low at early time points (2-7 dpi) with a significant increase at 13 dpi, indicating a lifestyle switch from biotrophy to necrotrophy between 7 and 13 dpi. AVRHt1 is the putative E. turcicum effector recognized by the maize resistance gene Ht1. Consistent with this, AVRHt1 was expressed in planta by race 23N, but transcripts were absent in race 13N. In addition, specific transposable elements were expressed in 23N only. Genes encoding the virulence-associated peptidases leupeptin-inhibiting protein 1 and fungalysin were expressed in planta. Transcriptional profiles of genes involved in secondary metabolite synthesis or cell wall degradation revealed the importance of these genes during late stages of infection (13 dpi). A total of 346 expressed candidate effectors were identified, including Ecp6 and proteins similar to the secreted in xylem (SIX) effectors common to formae speciales of Fusarium oxysporum, SIX13 and SIX5. Expression profiling of Ecp6 and SIX13-like indicated a peak in expression at 5 and 7 dpi compared to 2 and 13 dpi. Sequencing of SIX13-like from diverse isolates of E. turcicum revealed host-specific polymorphisms that were mostly non-synonymous, resulting in two groups of SIX13-like proteins that corresponded to the maize or sorghum origin of each isolate. This study suggests putative mechanisms whereby E. turcicum causes disease. Identification of the candidate effector SIX13-like is consistent with the infection mode of E. turcicum through the xylem of susceptible hosts.

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“…Furthermore, previous genomics studies have identified more than 600 genes coding for secreted proteins (Brown et al, 2012;King et al, 2015). Some have been identified at the proteome level (Lowe et al, 2015;Fabre et al, 2019) suggesting that F. graminearum could synthesize a large number of proteinous effectors.…”

Section: Introductionmentioning

confidence: 99%