John S. Reader, D.Phil.

jreader@med.unc.edu

Lab Personnel

Assistant Professor

• B.Sc. (Hons), Royal Holloway, University of London,1993
• D.Phil., University of Oxford, 1998
• Postdoc, The Scripps Research Institute, 1998-2005
• Research Assistant Professor, UNC-Chapel Hill, 2005-2009

• Joined the Department in 2009

Funding Sources

• American Heart Association
• National Institutes of Health

Research Interests

My laboratory’s main interest is the protein translation apparatus with a particular focus on aminoacyl-tRNA synthetases and tRNAs. Research in this area is fundamental to our understanding of the molecular and evolutionary processes that have led to the development and translation of the genetic code. We are also applying these studies towards the creation of novel therapeutics for the treatment of disease.

Aminoacyl-tRNA synthetases and tRNAs.

Aminoacyl-tRNA synthetases (aaRSs) are ancient enzymes that catalyze the essential first step of protein synthesis by covalently attaching each of the 20 standard amino acids to its cognate tRNA. Importantly, the aaRSs set the rules of the genetic code since each tRNA species contains the anticodon triplet of the code corresponding to the attached amino acid. All aaRSs catalyze the aminoacylation reaction in two steps: in the first step, the amino acid is activated to form an aminoacyl-adenylate intermediate, which is tightly bound to the catalytic core domain of the enzyme; in the second step, the activated amino acid is transferred to the 2´- (or 3´-)-OH of the terminal ribose at the 3´-end of tRNA. Each amino acid is activated by a distinct aaRS.

One focus of our current work is to use biochemical, bioinformatics and X-ray crystallography approaches, in conjunction with a novel reaction probe that we recently discovered, to understand the catalytic activity of a number of leucyl-tRNA synthetases. Our ultimate aim is to obtain not only a more complete picture of the molecular workings of leucyl-tRNA synthetases and aaRSs in general, but also new insights into their evolutionary history.

The function of aaRSs was originally thought to be restricted to their essential role in protein synthesis. However, recent research has dramatically changed this viewpoint. Whether it is because of their ancient and ubiquitous nature, catalytic activity or other reasons, evolution has conscripted this family of enzymes into a range of diverse non-canonical functions. Alternative functions for aaRS or ‘aaRS-like’ proteins have been described in amino acid biosynthesis, metabolite biosynthesis, antibiotic biosynthesis and even tRNA modification. We are currently exploring a number of examples these surprising non-canonical activities of aaRS and ‘aaRS-like’ enzymes from both bacteria and eukaryotes. Our analysis of the non-canonical activities of aaRSs excitingly promises to reveal previously unknown catalytic activities and novel biological functions of these enzymes.

Novel therapeutics

My laboratory is also actively harnessing the molecular insights we obtain from the study of aaRSs to aid in the development of novel therapeutics. One example is our discovery that a naturally occurring antibiotic, known as Agrocin 84, specifically targets bacterial leucyl-tRNA synthetases using a previously unknown mechanism. Although components of the translation apparatus are already prominent targets for existing antibiotics, the multitude of essential aaRSs remain a promising and underutilized source of new anti-infectives. We are therefore exploring the possibility of using agrocin 84 as the basis for the development of a novel antibiotic targeting a range of bacteria causing infections in humans.

Our studies are not restricted to the canonical and non-canonical functions of bacterial aaRSs. We are also studying the therapeutic potential of a naturally occurring fragment of human tyrosyl-tRNA synthetase (mini-TyrRS), which is a potent inducer of angiogenesis or new blood vessel growth in higher eukaryotes. Such pro-angiogenic molecules have been proposed to be a potential therapeutic strategy to treat patients with peripheral vascular disease such as diabetes or atherosclerosis sufferers. In collaboration with our long-standing colleague, Dr. Eleni Tzima, we are exploring the molecular mechanism by which mini-TyrRS regulates angiogenesis in vitro and in vivo.

Selected Publications

• Brown, M.V., Reader, J.S. and Tzima, E. Mammalian aminoacyl-tRNA synthetases: cell-signaling functions of the protein translation machinery. Vascular Pharmacology Invited review- in press
• Greenberg Y., King M., Kiosses W. B., Ewalt K., Yang X., Schimmel P.R., Reader J. S., & Tzima, E. (2008) The novel fragment of tyrosyl tRNA synthetase, mini-TyrRS, is secreted to induce an angiogenic response in endothelial cells. FASEB J. 22(5):1597-1605
• Kim J.-G., Park B.-K., Kim S.-U., Choi D., Nahm B. H., Moon J. S., Reader J. S., Farrand S. K., and Hwang I. (2006). Bases of Biocontrol: sequence predicts synthesis and mode of action of agrocin 84, the Trojan Horse antibiotic that controls crown gall. Proc. Natl. Acad. Sci. USA 103(23):8846-51
• Reader J.S., Ordoukanian P.T., J.-G. Kim, de Crécy-Lagard V., Hwang I., Farrand S.K., Schimmel, P. (2005). Major biocontrol of plant tumors targets tRNA synthetase. Science 309 (5740): 1533.
• [For review of work also see: The Face of Tumefaciens by J.S. Bardi, TSRI News and Views, Vol 5. Issue 31 / October 17, 2005
• Van Lanen S.G., Reader J.S., Swairjo, M.A., de Crécy-Lagard V., Lee, B., and Iwata-Reuyl, D. (2005) From cyclohydrolase to oxidoreductase: Discovery of nitrile reductase activity in a common fold. Proc. Natl. Acad. Sci. USA 22;102(12):4264-9
• Tzima E, Reader J.S., Irani-Tehrani M., Ewalt K. L., Schwartz M.A. and Schimmel P. (2005). VE-cadherin links tRNA synthetase cytokine to anti-angiogenic function. J. Biol. Chem. 280(4): 2405-8
• Metzgar D., Bacher J., Pezo V., Reader, J., Döring, V., Schimmel P., Marlière P. and de Crécy-Lagard V. (2004). Acinetobacter calcoaceticus: Acinetobacter sp. ADP1: an ideal model organism for genetic analysis and genome engineering. Nucleic Acids Research 32(19): 5780-90
• Reader J.S., Metzgar D., Schimmel P. and de Crécy-Lagard V. (2004). Identification of genes involved in biosynthesis of the modified nucleoside Queuosine. J. Biol. Chem. 279 (8): 6280-5
• Tzima E*, Reader J.S.*, Irani-Tehrani M., Ewalt K., Schwartz M.A. and Schimmel P. (2003). Biologically active fragment of a human tRNA synthetase inhibits fluid shear stress-activated responses of endothelial cells. Proc. Natl. Acad. Sci. USA 100 (25):14903-14907
  * These authors contributed equally to this work
• Reader, J.S. and Joyce G.F. (2002). A ribozyme composed of only two nucleotide subunits. Nature 420 (6917): 841-844.
• [For review of work also see: Minimalist RNA by Rebecca Rawls, C&EN 12/23/02: 8, Back two Bases by Philip Ball news@nature.com 12/16/02 and ‘Computer code was basis of first life’ by Roger Highfield, Daily Telegraph, UK:12/28/02].