Mechanism of Thioredoxin Reductase -- a Collaborative Project


Dr. Hondal received his Ph.D. in Chemistry from the Ohio State University in 1997. He then spent one year in the laboratory of Raymond Burk at Vanderbilt University studying the chemistry of selenomethionine and the structure of selenoprotein P. He continued his postdoctoral study under the direction of Ronald Raines at the University of Wisconsin-Madison as a NIH Postdoctoral Fellow. His work there focused on state of the art protein engineering techniques, including native chemical ligation and expressed protein ligation. His postdoctoral work at UW-Madison focused on methods for inserting non-natural amino acids into proteins as a means of addressing important structure-function questions in enzymology.

Research Description

There are two main areas of research in my lab. First, we are concerned with the mechanistic enzymology of high molecular weight thioredoxin reductases. The mammalian form of this enzyme contains the rare amino acid selenocysteine. One focus of this project is to understand why the mammalian enzyme requires this rare amino acid, while other homologues from C. elegans and D. melanogaster contain a conventional cysteine residue instead. We use protein engineering and protein semisynthesis techniques to study these enzymes. Semisynthesis allows us to insert a number of non-natural amino acids into the enzyme, as well as produce the mammalian form of the enzyme containing selenocysteine. X-ray crystallography, NMR spectroscopy, peptide synthesis, and steady-state kinetics are all techniques emphasized in my laboratory.

A second project involves developing new methods for regioselective disulfide bond formation in peptides and small proteins. A large challenge for peptide chemists is correctly pairing half-cystinyl residues. This is achieved through orthogonal protection/deprotection schemes using multiple protecting groups for the sulfhydryl group of cysteine. These groups are then selectively removed one at a time to form the correct disulfide bond.

Highlighted Publications

Eckenroth, BE, Lacey, BM, Lothrop, AP, Harris, KM, and Hondal RJ (2007) Investigation of the C-termindal Redox Center of High Mr Thioredoxin Reductases by Protein Engineering and Semisynthesis. Biochemistry In Press

Eckenroth, BE, Rould, MA, Hondal,RJ, and Everse SJ (2007) Structural and Biochemical Studies Reveal Differences in the Catalytic Mechanisms of Mammalian and Drosophila melanogaster Thioredoxin Reductases. Biochemistry 46, 4694-4705

Harris, KM, Flemer, S, and Hondal RJ (2007) Studies on deprotection of cysteine and selenocysteine side chain protecting groups. J. Pept. Sci 13, 81-93

Flemer, SJ, Lacey, BM and Hondal RJ. (2007). Synthesis of peptide substrates for mammalian thioredoxin reductase. J. Pept. Sci. 14(5):637-47

Eckenroth BE, Harris, K, Turanov, AA, Gladyshev, VN, Raines, RT, and Hondal, RJ (2006) Semisynthesis and characterization of mammalian thioredoxin reductase Biochemistry 45, 5158-5170.

Harris, KM and Hondal RJ. (2006) Deprotection of the p-methoxybenzyl group of selenocysteine by neighboring group participation. In Understanding Biology Using Peptides: Proceedings of the 19th American Peptide Symposium (Sylvie E. Blondelle, Ed.). Springer, New York, pgs 91-92.

Lacey, BM and Hondal, RJ (2006) Characterization of Mitochondrial Thioredoxin Reductase from C. elegans. Biochem. Biophys. Res. Commun. 346, 629-636.

View all Hondal publications here.

* indicates equal contribution

Recent Publications

Cunniff B, Snider GW, Fredette N, Stumpff J, Hondal RJ, Heintz NH (2014) Resolution of oxidative stress by thioredoxin reductase: Cysteine versus selenocysteine. Redox Biol 2: 475-84.

Ruggles EL, Deker PB, Hondal RJ (2014) Conformational analysis of oxidized peptide fragments of the C-terminal redox center in thioredoxin reductases by NMR spectroscopy. J Pept Sci 20(5): 349-60.

Lothrop AP, Snider GW, Flemer S Jr, Ruggles EL, Davidson RS, Lamb AL, Hondal RJ (2014) Compensating for the absence of selenocysteine in high-molecular weight thioredoxin reductases: the electrophilic activation hypothesis. Biochemistry 53(4): 664-74.

Lothrop AP, Snider GW, Ruggles EL, Patel AS, Lees WJ, Hondal RJ (2014) Selenium as an electron acceptor during the catalytic mechanism of thioredoxin reductase. Biochemistry 53(4): 654-63.

Snider GW, Dustin CM, Ruggles EL, Hondal RJ (2014) A mechanistic investigation of the C-terminal redox motif of thioredoxin reductase from Plasmodium falciparum. Biochemistry 53(3): 601-9.

Lothrop AP, Snider GW, Ruggles EL, Hondal RJ (2014) Why is mammalian thioredoxin reductase 1 so dependent upon the use of selenium? Biochemistry 53(3): 554-65.

Randall MJ, Spiess PC, Hristova M, Hondal RJ, van der Vliet A (2013) Acrolein-induced activation of mitogen-activated protein kinase signaling is mediated by alkylation of thioredoxin reductase and thioredoxin 1. Redox Biol 1(1): 265-75.

View all Hondal publications here.

Selected Awards

The Paul D. Boyer Memorial Award for Post-Doctoral Fellows (2001)

Best Publication Award, Journal of Peptide Science The prize is awarded by the Editorial Board of the Journal of Peptide Science to the communicating author for a paper published in the 2007-2009 time period in the Journal of Peptide Science. (2009)

Robert Hondal, Ph.D.

Hondal, Ph.D.

Associate Professor
Department of Biochemistry


Office: Given B413
Lab: Given B415

Lab Members

   Drew Barber, CMB Student
   Christopher Dustin, N/A
   Erik Ruggles, Research Associate

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