scholarly journals Inhibition of maize histone deacetylases by HC toxin, the host-selective toxin of Cochliobolus carbonum.

1995 ◽  
Vol 7 (11) ◽  
pp. 1941-1950 ◽  
Author(s):  
G Brosch ◽  
R Ransom ◽  
T Lechner ◽  
J D Walton ◽  
P Loidl
Keyword(s):  
Histone Deacetylases ◽  
Cochliobolus Carbonum ◽  
Hc Toxin

Inhibition of Maize Histone Deacetylases by HC Toxin, the Host-Selective Toxin of Cochliobolus carbonum

1995 ◽  
Vol 7 (11) ◽  
pp. 1941 ◽  
Author(s):  
Gerald Brosch ◽  
Richard Ransom ◽  
Thomas Lechner ◽  
Jonathan D. Walton ◽  
Peter Loidl
Keyword(s):  
Histone Deacetylases ◽  
Cochliobolus Carbonum ◽  
Hc Toxin

scholarly journals Fungal-induced protein hyperacetylation in maize identified by acetylome profiling

2017 ◽  
Vol 115 (1) ◽  
pp. 210-215 ◽  
Author(s):  
Justin W. Walley ◽  
Zhouxin Shen ◽  
Maxwell R. McReynolds ◽  
Eric A. Schmelz ◽  
Steven P. Briggs
Keyword(s):  
Immune Response ◽  
Posttranslational Modification ◽  
Protein Function ◽  
Histone Deacetylases ◽  
Effector Proteins ◽  
Protein Acetylation ◽  
Nonhistone Proteins ◽  
Cochliobolus Carbonum ◽  
Pathogen Effector ◽  
Hc Toxin

Lysine acetylation is a key posttranslational modification that regulates diverse proteins involved in a range of biological processes. The role of histone acetylation in plant defense is well established, and it is known that pathogen effector proteins encoding acetyltransferases can directly acetylate host proteins to alter immunity. However, it is unclear whether endogenous plant enzymes can modulate protein acetylation during an immune response. Here, we investigate how the effector molecule HC-toxin (HCT), a histone deacetylase inhibitor produced by the fungal pathogen Cochliobolus carbonum race 1, promotes virulence in maize through altering protein acetylation. Using mass spectrometry, we globally quantified the abundance of 3,636 proteins and the levels of acetylation at 2,791 sites in maize plants treated with HCT as well as HCT-deficient or HCT-producing strains of C. carbonum. Analyses of these data demonstrate that acetylation is a widespread posttranslational modification impacting proteins encoded by many intensively studied maize genes. Furthermore, the application of exogenous HCT enabled us to show that the activity of plant-encoded enzymes (histone deacetylases) can be modulated to alter acetylation of nonhistone proteins during an immune response. Collectively, these results provide a resource for further mechanistic studies examining the regulation of protein function by reversible acetylation and offer insight into the complex immune response triggered by virulent C. carbonum.

scholarly journals A Fatty Acid Synthase Gene in Cochliobolus carbonum Required for Production of HC-Toxin, Cyclo(d-Prolyl-l-Alanyl- d-Alanyl- l-2-Amino-9,10-Epoxi-8-Oxodecanoyl)

1997 ◽  
Vol 10 (2) ◽  
pp. 207-214 ◽  
Author(s):  
Joong-Hoon Ahn ◽  
Jonathan D. Walton
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthase ◽  
Cyclic Peptide ◽  
Decanoic Acid ◽  
Toxin Production ◽  
Gene Encoding ◽  
Cochliobolus Carbonum ◽  
Primary Amino ◽  
Hc Toxin

The fungal maize pathogen Cochliobolus carbonum produces a phytotoxic and cytostatic cyclic peptide, HC-toxin, of structure cyclo(D-prolyl-L-alanyl-D-alanyl-L-Aeo), in which Aeo stands for 2-amino-9,10-epoxi-8-oxodecanoic acid. Here we report the isolation of a gene, TOXC, that is present only in HC-toxin-producing (Tox2+) fungal strains. TOXC is present in most Tox2+ strains in three functional copies, all of which are on the same chromosome as the gene encoding HC-toxin synthetase. When all copies of TOXC are mutated by targeted gene disruption, the fungus grows and sporulates normally in vitro but no longer makes HC-toxin and is not pathogenic, indicating that TOXC has a specific role in HC-toxin production and hence virulence. The TOXC mRNA is 6.5 kb and the predicted product has 2,080 amino acids and a molecular weight of 233,000. The primary amino acid sequence is highly similar (45 to 47% identity) to the β subunit of fatty acid synthase from several lower eukaryotes, and contains, in the same order as in other β subunits, domains predicted to encode acetyl transferase, enoyl reductase, dehydratase, and malonyl-palmityl transferase. The most plausible function of TOXC is to contribute to the synthesis of the decanoic acid backbone of Aeo.

scholarly journals Cloning and Mapping of a Putative Barley NADPH-Dependent HC-Toxin Reductase

1997 ◽  
Vol 10 (2) ◽  
pp. 234-239 ◽  
Author(s):  
F. Han ◽  
A. Kleinhofs ◽  
A. Kilian ◽  
S. E. Ullrich
Keyword(s):  
Plant Species ◽  
Chromosome 9 ◽  
Immature Embryos ◽  
Chromosome 1 ◽  
Grass Species ◽  
Cochliobolus Carbonum ◽  
Wide Range ◽  
Young Leaves ◽  
High Conservation ◽  
Hc Toxin

The NADPH-dependent HC-toxin reductase (HCTR), encoded by Hm1 in maize, inactivates HC-toxin produced by the fungus Cochliobolus carbonum, and thus confers resistance to the pathogen. The fact that C. carbonum only infects maize (Zea mays) and is the only species known to produce HC-toxin raises the question: What are the biological functions of HCTR in other plant species? An HCTR-like enzyme may function to detoxify toxins produced by pathogens which infect other plant species (R. B. Meeley, G. S. Johal, S. E. Briggs, and J. D. Walton, Plant Cell, 4:71–77, 1992). Hm1 homolog in rice (Y. Hihara, M. Umeda, C. Hara, Q. Liu, S. Aotsuka, K. Toriyama, and H. Uchimiya, unpublished) and HCTR activity in barley, wheat, oats and sorghum have been reported (R. B. Meeley and J. D. Walton, Plant Physiol. 97:1080–1086, 1993). To investigate the sequence conservation of Hm1 and HCTR in barley and the possible relationship of barley Hm1 homolog to the known disease resistance genes, we cloned and mapped a barley (Hordeum vulgare) Hm1-like gene. A putative full-length cDNA clone, Bhm1-18, was isolated from a cDNA library consisting of mRNA from young leaves, inflorescences, and immature embryos. This 1,297-bp clone encodes 363 amino acids which show great similarity (81.6%) with the amino acid sequence of HM1 in maize. Two loci were mapped to barley molecular marker linkage maps with Bhm1-18 as the probe; locus A (Bhm1A) on the long arm of chromosome 1, and locus B (Bhm1B) on the short arm of chromosome 1 which is syntenic to maize chromosome 9 containing the Hm2 locus. The Bhm1-18 probe hybridized strongly to a Southern blot of a wide range of grass species, indicating high conservation of HCTR at the DNA sequence level among grasses. The HCTR mRNA was detected in barley roots, leaves, inflorescences, and immature embryos. The conservation of the HCTR sequence, together with its expression in other plant species (R. B. Meeley and J. D. Walton, Plant Physiol. 97:1080–1086, 1993), suggests HCTR plays an important functional role in other plant species.

scholarly journals An Extended Physical Map of the TOX2 Locus of Cochliobolus carbonum Required for Biosynthesis of HC-Toxin

2002 ◽  
Vol 35 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Joong-Hoon Ahn ◽  
Yi-Qiang Cheng ◽  
Jonathan D. Walton
Keyword(s):  
Physical Map ◽  
Cochliobolus Carbonum ◽  
Hc Toxin

scholarly journals Histone Deacetylase Activity and Phytotoxic Effects Following Exposure of Duckweed (Lemna pausicostata L.) to Apicidin and HC-Toxin

2001 ◽  
Vol 91 (12) ◽  
pp. 1141-1148 ◽  
Author(s):  
Hamed K. Abbas ◽  
John W. Gronwald ◽  
Kathryn L. Plaisance ◽  
Rex N. Paul ◽  
Yin W. Lee
Keyword(s):  
Cell Division ◽  
Histone Deacetylase ◽  
Chlorophyll Synthesis ◽  
Effective Concentration ◽  
Starch Accumulation ◽  
Fusarium Spp ◽  
Cochliobolus Carbonum ◽  
Hc Toxin ◽  
Cyclic Tetrapeptide

The effects of two cyclic tetrapeptide fungal toxins, apicidin (from Fusarium spp.) and HC-toxin (from Cochliobolus carbonum), on duckweed (Lemna pausicostata L.) were examined. Both toxins inhibited histone deacetylase (HD) activity from duckweed plantlets; the effective concentration (EC50) for inhibition of HD was 5.6 and 1.1 μM for apicidin and HC-toxin, respectively. Approximately 65 and 85% of in vitro HD activity was inhibited by 50 μM apicidin or HC-toxin, respectively. Exposing duckweed for 72 h to apicidin or HC-toxin (25 or 50 μM) enhanced cellular leakage, impaired chlorophyll synthesis, and inhibited growth (cell division). At equivalent concentrations, the effects of HC-toxin were more pronounced than those of apicidin. In fronds, 72 h of exposure to 50 μM apicidin resulted in chloroplast deterioration indicated by loss of orientation and excess starch accumulation. In roots, a 72-h treatment with 50 μM apicidin resulted in the loss of the root cap and increased vacuolization and starch accumulation in plastids.

scholarly journals Fungal Induced Protein Hyperacetylation Identified by Acetylome Profiling

2016 ◽  
Author(s):  
Justin W Walley ◽  
Zhouxin Shen ◽  
Maxwell R. McReynolds ◽  
Steven P. Briggs
Keyword(s):  
Immune Response ◽  
Protein Function ◽  
Effector Proteins ◽  
Protein Acetylation ◽  
Post Translational Modification ◽  
Cochliobolus Carbonum ◽  
Pathogen Virulence ◽  
Pathogen Effector ◽  
Race 1 ◽  
Hc Toxin

ABSTRACTLysine acetylation is a key post-translational modification that regulates diverse proteins involved in a range of biological processes. The role of histone acetylation in plant defense is well established and it is known that pathogen effector proteins encoding acetyltransferses can directly acetylate host proteins to alter immunity. However, it is unclear whether endogenous plant enzymes can modulate protein acetylation during an immune response. Here we investigate how the effector molecule HC-toxin, a histone deacetylase inhibitor, produced by Cochliobolus carbonum race 1 promotes pathogen virulence in maize through altering protein acetylation. Using mass spectrometry we globally quantified the abundance of 3,636 proteins and the levels of acetylation at 2,791 sites in maize plants treated with HC-toxin as well as HC-toxin deficient or producing strains of C. carbonum. Analyses of these data demonstrate that acetylation is a widespread post-translational modification impacting proteins encoded by many intensively studied maize genes. Furthermore, the application of exogenous HC-toxin enabled us to show that the activity of plant-encoded enzymes can be modulated to alter acetylation of non-histone proteins during an immune response. Collectively, these results provide a resource for further mechanistic studies examining the regulation of protein function and offer insight into the complex immune response triggered by virulent C. carbonum.

scholarly journals Reduced Virulence Caused by Meiotic Instability of the TOX2 Chromosome of the Maize Pathogen Cochliobolus carbonum

2000 ◽  
Vol 13 (1) ◽  
pp. 80-87 ◽  
Author(s):  
John W. Pitkin ◽  
Anastasia Nikolskaya ◽  
Joong-Hoon Ahn ◽  
Jonathan D. Walton
Keyword(s):  
Cyclic Peptide ◽  
Normal Growth ◽  
Pathogenic Fungi ◽  
Housekeeping Genes ◽  
Toxin Production ◽  
In Planta ◽  
Cochliobolus Carbonum ◽  
Hc Toxin ◽  
Reduced Rate ◽  
Functional Copy

The mechanisms by which pathogenic fungi evolve are poorly understood. Production of the host-selective cyclic peptide HC-toxin is controlled by a complex locus, TOX2, in the plant pathogen Cochliobolus carbonum. Crosses between toxin-producing (Tox2+) and toxin-nonproducing (Tox2-) isolates, as well as crosses between isolates in which the TOX2 genes were on chromosomes of different size, yielded progeny that had lost one or more copies of one or more of the TOX2 genes. Of approximately 200 progeny analyzed, eight (4%) had lost at least one TOX2 gene. All of them still had at least one functional copy of all of the known genes required for HC-toxin production (HTS1, TOXA, TOXC, and TOXE). Most deletion strains could be explained by simple chromosome breaks resulting in the loss of major contiguous portions (0.8 to 1.4 Mb) of the 3.5-Mb TOX2 chromosome, whereas others had more complicated patterns. All deletion strains had normal growth and were fertile, indicating that the 1.4 Mb of DNA contained no essential housekeeping genes. Most strains were also still virulent (Tox2+), but two had a novel phenotype of reduced virulence (RV), characterized by smaller lesions that expanded at a reduced rate and an inability to colonize plants systemically. Although the RV strains made no detectable HC-toxin in culture, the RV phenotype was dependent on the presence of a functional copy of HTS1, which encodes the central enzyme in HC-toxin biosynthesis. We propose that the RV strains still make a low level of HC-toxin, at least in planta, and that this is due to the loss of one or more genes that contribute to, but are not absolutely required for, HC-toxin synthesis.

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