Chemical Constitution of the Host-Specific Toxin of <i>Helminthosporium carbonum</i>

Pringle, Ross B.

doi:10.1104/pp.46.1.45

Cited by 34 publications

(22 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Introductionmentioning

confidence: 99%

“…Additional ninhydrin-reacting substances were produced in low yield and probably represented secondary hydrolysis products of the unstable amino acids. (4,5,8,9,16,17 The most recent studies have been concerned with the hostspecific toxin of Helminthosporium carbonum Ullstrup, which is toxic to susceptible inbred dent corn (Zea inays L.) (3,6,7,14,15,19).Although each of these host-specific toxins has been isolated and crystallized in milligram quantities, because of the difficulty of isolation and their great instability only HC2 toxin has been characterized to any extent (5, 6, 7). It was shown to have a molecular formula approximating C32H.NMO,O by analysis of crystalline material and by analysis of a crystalline hydrochloride derivative.…”

mentioning

confidence: 99%

“…var. subglabrescens [Steud.1 A. F. Hill) (10,12,13 The most recent studies have been concerned with the hostspecific toxin of Helminthosporium carbonum Ullstrup, which is toxic to susceptible inbred dent corn (Zea inays L.) (3,6,7,14,15,19).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Amino Acid Composition of the Host-specific Toxin of Helminthosporium carbonum

Pringle¹

1971

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

The host-specific toxin of Helminthosporium carbonum (C32HsoNoO,o) was hydrolyzed by 6 N HCI to yield a number of a-amino acids. The common amino acids, proline and alanine, occurred in a ratio of 1 :2. Two other unstable a-amino acids that produced lower color values with ninhydrin were also produced. One of these was tentatively identified as 2-amino-2,3-dehydro-3-methylpentanoic acid by electrolytic reduction to isoleucine. Additional ninhydrin-reacting substances were produced in low yield and probably represented secondary hydrolysis products of the unstable amino acids. (4,5,8,9,16,17 The most recent studies have been concerned with the hostspecific toxin of Helminthosporium carbonum Ullstrup, which is toxic to susceptible inbred dent corn (Zea inays L.) (3,6,7,14,15,19).Although each of these host-specific toxins has been isolated and crystallized in milligram quantities, because of the difficulty of isolation and their great instability only HC2 toxin has been characterized to any extent (5, 6, 7). It was shown to have a molecular formula approximating C32H.NMO,O by analysis of crystalline material and by analysis of a crystalline hydrochloride derivative. The molecular weight was determined by bioassay of the eluate of a Sephadex G-10 chromatography column and shown to be slightly less than 700. The toxin appeared to be a cyclic peptide, because, although it did not react with ninhydrin or fluorodinitrobenzene, after acid hydrolysis it yielded compounds which reacted to these reagents. The ultraviolet absorption spectrum of freshly lyophilized toxin dissolved in freshly distilled ethanol showed a single, well defined maximum at 230 nm. The molar absorptivity of a 1.4 X 10' M solution (assuming a molecular weight of 679) was approximately 5000. The position of the maximum and its relatively high intensity suggested a double bond in the vicinity of a carbonyl group, possibly an a , fl-unsaturated amide. Because the presence of such a function in HC toxin would explain the relative instability of the molecule, further work was done in characterizing the ninhydrin-reacting products of acid hydrolysis. MATERIAL AND METHODS

show abstract

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Amino Acid Composition of the Host-specific Toxin of Helminthosporium carbonum

Pringle¹

1971

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…A final class of HDACi is a series of cyclic peptides exemplified among others by Trapoxin A, H-C toxin, chlamydocin and apicidin [159][160][161][162][163]. All these structures contain a proline or pipecolinic acid residue and a non-proteinogenic long aliphatic amino acid (L-Aoe or L-Aoda) that may act as a substrate analog.…”

Section: Classes Of Hdaci's and Their Anticancer Propertiesmentioning

confidence: 99%

HDACs, histone deacetylation and gene transcription: from molecular biology to cancer therapeutics

et al. 2007

View full text Add to dashboard Cite

Histone deacetylases (HDACs) and histone acetyl transferases (HATs) are two counteracting enzyme families whose enzymatic activity controls the acetylation state of protein lysine residues, notably those contained in the N-terminal extensions of the core histones. Acetylation of histones affects gene expression through its influence on chromatin conformation. In addition, several non-histone proteins are regulated in their stability or biological function by the acetylation state of specific lysine residues. HDACs intervene in a multitude of biological processes and are part of a multiprotein family in which each member has its specialized functions. In addition, HDAC activity is tightly controlled through targeted recruitment, protein-protein interactions and post-translational modifications. Control of cell cycle progression, cell survival and differentiation are among the most important roles of these enzymes. Since these processes are affected by malignant transformation, HDAC inhibitors were developed as antineoplastic drugs and are showing encouraging efficacy in cancer patients.

show abstract

“…Fractions with host-specific toxicity were dried, and the residues were stored under nitrogen over CaCl2 at -20 C. This preparation caused 50% inhibition of susceptible corn roots at 0.2 ug/ml, and of resistant roots at 20 ug/ml, when assayed by the seedling root growth method (16). Thus, the toxin preparation was active at 0.295 ,uM (mol wt = 679), which is as active as the best crystalline preparations (14,15). Reaction mixtures were assayed before and after each experiment; there were no losses in host-specific toxicity.…”

Section: Methodsmentioning

confidence: 77%

Effects of Helminthosporium carbonum Toxin on Nitrate Uptake and Reduction by Corn Tissues

Yoder¹,

Scheffer²

1973

Plant Physiol.

View full text Add to dashboard Cite

Susceptible corn tissues exposed to the host-specific toxin of Helminthosporiuna carbonum race 1 reduced more nitrate to nitrite than did control tissues, as measured by an in vivo method. There were no differences in nitrate reductase activities extracted from treated and control tissues and assayed by an in vitro method. Toxin-treated susceptible roots (15,16). This "host-specific toxin" is required by the fungus for pathogenicity and for initial colonization of susceptible plant tissues (1, 16). Among its described physiological effects on susceptible tissues, HC toxin increases electrolyte leakage, respiration, dark fixation of CO2, and the incorporation of uridine and amino acids. Most of these effects are not evident unless tissues are exposed to toxin for 8 to 12 hr (9, 17); they could be secondary results of an initial toxic effect.The original aim of this work was to determine whether or not toxin has a direct effect on protein synthesis. An inducible enzyme, nitrate reductase, was chosen to study this question. Zielke and Filner (23) MATERIALS AND METHODSPlants. H. carbonum-resistant (Prl X K61) or susceptible (Pr X K61) corn hybrids were used in all experiments. Roots were produced by two methods. (a) Seeds (250) were incubated 8 to 12 hr in water, then were washed and placed embryo side down on a cheesecloth surface in a beaker above 4 liters of 0.2 mm CaCl2. A second layer of cheesecloth was placed over the seeds, the beaker was covered with plastic film, and the solution was aerated. Primary roots were used 4 days later when they were 8 to 12 cm long. (b) Seeds (150) were placed embryo side down on an agar medium (100 ml of 0.9% agar in a 15-cm Petri dish) containing White's solution (20) minus nitrate. After 60 to 84 hr of incubation, the germinated seeds had 4-to 8-cm roots which were used as experimental tissues.Toxin Preparation. Toxin was isolated from H. carbonum race 1 by previously described procedures (15, 21). Culture filtrates were concentrated, deproteinized by methanol precipitation, and extracted with chloroform. The chloroform solution was taken to dryness in vacuo, and the residue was dissolved in ethanol, mixed with 20 volumes of diethyl ether, and stored at 5 C for 24 hr. The precipitate was discarded, and the solution was taken to dryness. A second ethanol-ether extract was taken to dryness, dissolved in water, and passed through a BioGel P-2 column. Fractions with host-specific toxicity were dried, and the residues were stored under nitrogen over CaCl2 at -20 C. This preparation caused 50% inhibition of susceptible corn roots at 0.2 ug/ml, and of resistant roots at 20 ug/ml, when assayed by the seedling root growth method (16). Thus, the toxin preparation was active at 0.295 ,uM (mol wt = 679), which is as active as the best crystalline preparations (14, 15). Reaction mixtures were assayed before and after each experiment; there were no losses in host-specific toxicity.Nitrate Reductase Assays. Nitrate reductase activity was determined in vivo by the method of Ferr...

show abstract

Chemical Constitution of the Host-Specific Toxin of Helminthosporium carbonum

Cited by 34 publications

References 7 publications

Amino Acid Composition of the Host-specific Toxin of Helminthosporium carbonum

Amino Acid Composition of the Host-specific Toxin of Helminthosporium carbonum

HDACs, histone deacetylation and gene transcription: from molecular biology to cancer therapeutics

Effects of Helminthosporium carbonum Toxin on Nitrate Uptake and Reduction by Corn Tissues

Contact Info

Product

Resources

About