Next Article in Journal
BiP Negatively Affects Ricin Transport
Next Article in Special Issue
Heparin-Binding Epidermal Growth Factor-like Growth Factor/Diphtheria Toxin Receptor in Normal and Neoplastic Hematopoiesis
Previous Article in Journal
Sedimentation Patterns of Toxin-Producing Microcystis Morphospecies in Freshwater Reservoirs
Toxins 2013, 5(5), 958-968; doi:10.3390/toxins5050958
Brief Report

Insights into Diphthamide, Key Diphtheria Toxin Effector

1,†
, 1,†
, 2
, 3
 and 1,2,*
1 Institut für Biologie, FG Mikrobiologie, Universität Kassel, Kassel D-34132, Germany 2 Department of Genetics, University of Leicester, Leicester LE1 7RH, UK 3 Centre for Gene Regulation & Expression, University of Dundee, Dundee, DD1 5EH, Scotland These authors contributed equally to this work.
* Author to whom correspondence should be addressed.
Received: 14 March 2013 / Revised: 17 April 2013 / Accepted: 26 April 2013 / Published: 3 May 2013
(This article belongs to the Special Issue Diphtheria Toxin)
View Full-Text   |   Download PDF [1001 KB, 6 May 2013; original version 3 May 2013]   |   Browse Figures

Abstract

Diphtheria toxin (DT) inhibits eukaryotic translation elongation factor 2 (eEF2) by ADP-ribosylation in a fashion that requires diphthamide, a modified histidine residue on eEF2. In budding yeast, diphthamide formation involves seven genes, DPH1-DPH7. In an effort to further study diphthamide synthesis and interrelation among the Dph proteins, we found, by expression in E. coli and co-immune precipitation in yeast, that Dph1 and Dph2 interact and that they form a complex with Dph3. Protein-protein interaction mapping shows that Dph1-Dph3 complex formation can be dissected by progressive DPH1 gene truncations. This identifies N- and C-terminal domains on Dph1 that are crucial for diphthamide synthesis, DT action and cytotoxicity of sordarin, another microbial eEF2 inhibitor. Intriguingly, dph1 truncation mutants are sensitive to overexpression of DPH5, the gene necessary to synthesize diphthine from the first diphthamide pathway intermediate produced by Dph1-Dph3. This is in stark contrast to dph6 mutants, which also lack the ability to form diphthamide but are resistant to growth inhibition by excess Dph5 levels. As judged from site-specific mutagenesis, the amidation reaction itself relies on a conserved ATP binding domain in Dph6 that, when altered, blocks diphthamide formation and confers resistance to eEF2 inhibition by sordarin.
Keywords: diphtheria toxin; sordarin; diphthamide biosynthesis; DPH1-DPH7 genes diphtheria toxin; sordarin; diphthamide biosynthesis; DPH1-DPH7 genes
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Share & Cite This Article

Export to BibTeX |
EndNote


MDPI and ACS Style

Abdel-Fattah, W.; Scheidt, V.; Uthman, S.; Stark, M.J.R.; Schaffrath, R. Insights into Diphthamide, Key Diphtheria Toxin Effector. Toxins 2013, 5, 958-968.

View more citation formats

Supplement

Related Articles

Article Metrics

Comments

Citing Articles

[Return to top]
Toxins EISSN 2072-6651 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert