Brief Biography:
My doctoral research at Central Drug Research Institute, Lucknow India was focused on “Structural and biochemical characterization of proteins over-expressed under nutrient starvation/latent phase in Mycobacterium tuberculsois H37Rv”. During latent phase Mycobacterium tuberculosis causative agent of TB can survive decades in human host without any symptoms of disease. There are some proteins which are up-regulated during these condition and are thought to be very important for new life style of bacteria. Structure-function studies on proteins like Lysine ?-aminotansferase (MtbLAT) and L-Alanine dehydrogenase (MtbALD) that are experimentally proved to be important for adaptation/maintenance of tuberculosis persistence and ranked among the top-3 targets against tuberculosis persistence by the TB-Structural-Genomics Consortium. During my PhD, I completed two gene to structure projects solving the three dimensional structure of Lysine ?-aminotransferase (Rv3290c) and Alanine dehydrogenase (Rv2780c). After elucidation of the structures I carried out virtual screening to find better inhibitors against these proteins and also solved the structure of Rv3290c with one potent inhibitor. Structure of proteins and its complex with different substrate and product provide direct evidence how these proteins carry out different reactions by using simple “switch”.
a. Tripathi, SM., Agarwal, A. & Ramachandran, R. Mutational analysis of M. tuberculosis Lysine ?- aminotransferase and inhibitor co-crystal structures, reveals distinct binding modes. Biochemical and Biophysical Research Communication, 2015, 463, 154-60.
b. Tripathi, SM. & Ramachandran, R. Crystal Structures of the Mycobacterium tuberculosis secretory antigen alanine dehydrogenase (Rv2780) in the apo and ternary complex captures ‘open’ and ‘closed’ enzyme conformations. Proteins: Structure, Function, and Bioinformatics, 2008, 72, 1089-1095.
c. Tripathi, SM. & Ramachandran, R. Direct evidence for a glutamate switch necessary for substrate recognition: crystal structures of lysine epsilon-aminotransferase (Rv3290c) from Mycobacterium tuberculosis H37Rv. Journal of Molecular Biology, 2006, 362, 877-886.
d. Tripathi, SM. & Ramachandran, R. Overexpression, purification, crystallization and preliminary X-ray analysis of Rv2780 from Mycobacterium tuberculosis H37Rv. Acta Crystallograph Sect F Struct Biol Cryst Commun. 2008, F64, 367-370.
e. Tripathi, SM. & Ramachandran, R. Overexpression, purification and crystallization of lysine epsilon-aminotransferase (Rv3290c) from Mycobacterium tuberculosis H37Rv. Acta Crystallograph Sect F Struct Biol Cryst Commun. 2006, F62, 572-575.
f. Dube, D; Tripathi, SM. & Ramachandran, R. Identification of in vitro inhibitors of Mycobacterium tuberculosis lysine ?-aminotransferase by pharmacophore mapping and three-dimensional flexible searches. Med. Chem. Res. 2008, 7, 182-188.
2. During my Postdoctoral work at Dr. Tom Poulos lab (University of California Irvine), my research was mainly focussed on structural and functional characterization of heme proteins. Cytochromes P450 catalyze the oxidation of organic compounds including drugs by insertion of an activated oxygen atom into an inert C–H bond. This process requires that electrons be funneled to the P450 heme via a redox partner. Electron transfer mediated by redox-partner, protein–protein interactions is an essential prerequisite for the activation of molecular oxygen within the P450 reaction cycle. The crystal structures of all three components cytochromeP450cam, putidaredoxin reductase (Pdr), putidaredoxin (Pdx) and the Pdr-Pdx complex are known leaving the P450cam-Pdx complex as the final structure to be solved in the P450cam system. Pdx, which plays an effector role by inducing structural changes in P450cam required for activity although the detail of these changes has remained unknown. I solved 2.09Å crystal structure of the electron transfer complex between P450cam and Pdx in two different forms by using X-ray crystallography. The results indicate that part of the effector role of Pdx is to open the active site and free key catalytic residues in order to establish the proton relay network required for oxygen activation.
a. Tripathi, SM., Li, H. & Poulos, TL. Structural Basis for Effector Control and Redox Partner Recognition in Cytochrome P450. Science, 2013, 40, 1227-1230.
b. Madrona, Y., Tripathi, SM., Li, H. & Poulos, TL. Crystal structures of substrate-free and nitrosyl cytochrome P450cin: implications for O(2) activation. Biochemistry, 2012, 51, 6623–6631.
At present I am working as Scientist in-Charge of Macromolecular Structure function core facility at Chemistry and Biochemistry Department at University of California Santa Cruz. Where I am actively involved in research in addition to teaching and training graduate and undergraduate students,
I have published more than 10 research articles in prestigious journal and awarded with best Postdoctoral Scientist at University of California Irvine.
Academic positions:
Scientist in-Charge Structural Biology Facility
University of California Santa Cruz
Research interests:
Macromolecular Crystallography, Protein Structure and Function, Biophysics, X-ray Crystallography, Protein-protein interaction, Three dimensional Structure determination of Macromolecules
What I think of the idea behind WebmedCentral:
WebmedCentral is an excellent platform for a scientist to publish and contribute in the field of science
Home Page:
http://strucbiol.pbsci.ucsc.edu/contacts
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