Dr. David Johnson

Dr. David Johnson

David Johnson, Ph.D.
Professor, Department of Biomedical Sciences
Adjunct Professor of Biological Sciences,
  College of Arts & Sciences, ETSU


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Contact Information:
Room A105 Stanton Gerber Hall (Bldg. 178), VA Medical Center
Fax:  423-439-2030


  • 1967 B.S. in Chemistry, University of Memphis
  • 1973 Ph.D. in Chemistry, University of Memphis  
  • 1978 Post-Doctoral in Biochemistry, University of Georgia (Athens)

Professional Background:

 2000     Visiting Professor in Immunopharmacology at the University of Southampton for three months, August - October, in the laboratory of Dr. Andrew Walls

1997      Methods in Molecular Biology Workshop - ETSU COM July 14-25, 1997

1991      Wellcome visiting professor in the Laboratory of Molecular Biophysics with Dr. Geoffrey Barton, University of Oxford, England, May and June, "Molecular Modeling of Mast Cell Tryptases", supported by a Burroughs Wellcome Fund Research Travel Grant - May 1 -June 30, 1991.

1990      Course on computer based multiple sequence alignment of DNA and proteins, Pittsburgh Super Computer Center - Aug 5-8; all expenses paid by the PSCC.

1985      Wellcome visiting scientist at Strangeways Research Laboratory with Dr. Alan Barrett, Cambridge, England, April 15 through July 15; "Human Mast Cell Tryptase", supported by a Burroughs Wellcome Fund Research Travel Grant

Research/Teaching Interests:

1.   Protein Structure and Function, Enzymology, Proteomics
2.   Human serine proteases and their inhibitors

Research /Teaching Interests:

Research deals with proteolytic enzymes and their inhibitors, including protein purification, characterization, sequencing, structure function relationships, kinetics, and regulation. Particular emphasis is placed on the roles of proteases and inhibitors in the pathogenesis of human diseases. Work on the structure of human alpha-1-proteinase inhibitor led to the discovery of its active site and we showed that oxidation of a methionine residue in the inhibitory site of α1-PI caused the loss of elastase inhibitory activity. This finding resulted in the hypothesis that oxidants can lead to a lung-localized inhibitor deficiency. A deficiency of α1-PI, which normally inhibits neutrophil elastase, is known to cause emphysema. This led to studies of the reactions of ozone and nitrogen dioxide on the function of human α1-PI and the secretory leukocyte proteinase inhibitor found in human bronchial mucus, which also inhibits neutrophil elastase. Another long-standing project focuses on the structure and function of human mast cell tryptase, an unusual serine protease that is the most abundant protein in mast cells. Recently, tryptase has been shown to activate protease zymogens, suggesting a critical role in tumor growth and the pathogenesis of arthritis. Finally, tryptase has an anticoagulant function due to the limited proteolysis of blood coagulation proteins, including fibrinogen and high molecular weight kininogen. Currently, research focuses on the expression of recombinant human mast cell and neutrophil serine proteases, as well as human enterokinase and C-reactive protein, using Pichia pastoris as the host organism.

Research Support:

2001-2004          “Recombinant Human Mast Cell Tryptases”, NIAID, NIH R15 AI45549, $126,954.
2007-2011          "Human Cathepsin G:  Expression, C-Terminal Processing and Dual Specificity" National Heart Lung and Blood Institute 1R15HL091770   $210,230

Lab Members:

Eliot Smith – Ph.D. Graduate student
Evan Perry – Undergraduate Honors student
Megan Sears – Undergraduate – Biological Sciences

Selected References:   

Coffman, Lan; Brown, Julie; Johnson, David; Parthasarathy, Narayanan; D'Agostino Jr., Ralph; Lively, Mark; Hua, Xiaoyang; Tilley, Stephen; Muller-Esterl, Werner; Willingham, Mark; Torti, Frank; Torti, Suzy.  Cleavage of High Molecular Weight Kininogen by Elastase and Tryptase is Inhibited by Ferritin. American Journal of Physiology 294, L505-515, 2008.  

Smita Negi, Ahmad Halawa, David S. Chi, Christopher Miller, Fred Hossler, George Youngberg, David A. Johnson and Guha Krishnaswamy MAST CELL REGULATION OF CARDIOVASCULAR INFLAMMATION I:  COGNATE AND NON-COGNATE INTERACTIONS In: Mast Cells and Cardiovascular Disease.  Ed. Joseph J, Nova Science Publishers, Hauppauge, NY 2009 accepted 3/10/2010  

Sanjay K. Singh, Avinash Thirumalai, David J. Hammond, Jr., Michael K. Pangburn, Vinod K. Mishra, David A. Johnson, Antonio E. Rusiñol, and Alok Agrawal Exposing a hidden functional site of C-reactive protein by site-directed mutagenesis  J.Biol.Chem. 287, 3550–3558, 2012. 

 Eliot T. Smith and David A. Johnson, Human Enteropeptidase Light Chain: Bioengineering of Recombinants and Kinetic Investigations of Structure and Function Protein Science 22, 577-585, 2013. 

Book Chapters