Rajat Sapra, Ph.D.

Host-Pathogen Proteomics: Current research projects are focused on the identification of pre-symptomatic proteomic biomarkers in host-pathogen relationships using Bacillus anthracis toxins and mouse macrophages as host; and validating these biomarkers for clinical use.We use differential proteomics, defined as the identification of differential regulation of the cellular proteome in response to an external stimulus, to identify and catalogue the proteins that are regulated in response to the host invasion.This is accomplished by using the gel based proteomic techniques like difference in-gel electrophoresis (DIGE) followed by mass spectrometric identification of proteins and purely mass spectrometry-based techniques like isotope coded affinity tags (ICAT).

Proteomic Identification of Stress Response in Sulfate Reducing Bacteria: Sulfate-reducing bacteria (SRB) represent a class of organisms that generate energy through electron transfer-coupled phosphorylation using sulfate as the terminal electron acceptor.The ability of these SRB to reduce metals like Uranium and Chromium has the potential for bioremediation of toxic metals. Desulfovibrio vulgaris Hildenborough (DvH) is one such model SRB that is the subject of a multi-lab Genomes-to-Life (GTL) research project. We are using proteomics to understand the ability of DvH to respond to and survive external stresses.The project focuses on the identification of the proteome of DvH in the wild-type cells and comparing the response of the cells to external stresses (e.g., oxygen, heavy metal exposure (U, Co, Hg, Ni, and Cr), reductant limitation, phosphate restriction, and pH).

Enhanced Biomass-Bioenergy Conversion through Enzyme Engineering: The efficient conversion of biomass resources to fuels is a key component for the cheap production of alternative fuels.Naturally occurring enzymes can be used to covert biomass into the desired end-products.However, enzymes used by nature to accomplish this conversion are a part of a complex consortium of metabolic pathways, optimized to a specific operating environment through evolutionary forces.We utilize protein and metabolic engineering to adapt these enzymes and pathways to increase conversion efficiency of biomass to bioenergy.Our efforts involve a parallel approach that includes both numerical modeling to determine preferred mutant gene sequences, followed by site-directed mutagenesis of the native enzyme.A high-throughput enzyme screening strategy is used for rapid, reliable identification of desired enzymatic characteristics.

Recent Publications

Sapra, R; Gaucher, SP; Lachmann, JS; Buffleben, GM; Chirica, GS; Comer, JE; Peterson, JW; Chopra, AK; Singh, AK. Proteomic analyses of murine macrophages treated with Bacillus anthracis lethal toxin. Microbial Pathogenesis; OCT-NOV 2006; v.41, no.4-5, p.157-167

Johnston, W; Cooney, MJ; Liaw, BY; Sapra, R; Adams, MWW. (2005) Design and characterization of redox enzyme electrodes: new perspectives on established techniques with application to an extremophilic hydrogenase. Enzyme and Microbial Technology. 36(4) 540-549.

Sapra R., Bagramyan, K., Adams, M.W.W. (2003) The Simplest Respiratory System: Proton Reduction Coupled to Proton Translocation. Proceedings of the National Academy of Sciences U.S.A., 100(13) 7545-50.
PubMed

Adams et al. (2001) A Key Role for Sulfur in Peptide Metabolism and in the Regulation of the Three Hydrogenases in the Hyperthermophilic Achaean Pyrococcus furiosus. Journal of Bacteriology, 183(2) 716-24.
PubMed

Sapra, R., Verhagen, M.F.J.M., Adams , M.W.W. (2000) Purification and Characterization of a Membrane-Bound Hydrogenase from the Hyperthermophilic Archaeon Pyrococcus furiosus. Journal of Bacteriology, 182(12) 3423-8.
PubMed

Carney, G.E., Wade, A.A., Sapra, R, Goldstein, E.S., Bender, M. (1997) DHR3, an ecdysone-inducible early-late gene encoding a Drosophila nuclear receptor, is required for embryogenesis. Proceedings of the National Academy of Sciences U.S.A., 94(22) 12024-9.
PubMed

Appointments

2003–Present—Postdoctoral Fellow, Sandia National Laboratories, Livermore CA

Education

1996-2003:	Ph.D., Biochemistry & Molecular Biology, University of Georgia, Athens, GA NSF Fellowship for Interdisciplinary Research; Research Fellow Center for Metalloenzyme Studies
1992-1996:	B.S., Genetics, University of Georgia, Athens, GA

Contact Information

Dr. Rajat Sapra
Biosystems Research Department
Sandia National Laboratories
MS 9291, PO Box 969
7011 East Avenue
Livermore, CA 94551-0969

rsapra@sandia.gov
phone: 925-294-1580
fax: 925-294-3020