Indraneel Ghosh
Professor, BIO5 Institute
Professor, Chemistry and Biochemistry-Sci
Primary Department
Department Affiliations
(520) 621-6331
Work Summary
The broad objective of our research program in Bioorganic Chemistry and Chemical Biology is to construct protein therapeutics, protein mimetics, biomaterials, and biosensors. Our research at the University of Arizona is highly multidisciplinary and utilizes techniques in organic synthesis, biochemistry, molecular biology, and a host of physical characterization methods. Our research motto is simple: Unraveling mysteries and Enabling discoveries.
Research Interest
Professor Neel Ghosh, is the Emily Davis and Homer Weed Distinguished Professor ’08 at the University of Arizona. His laboratory is broadly interested in Chemical Biology and Protein Design and Engineering with a focus on developing new tools and methods for advancing human health. The laboratory has a particular current interest in understanding protein kinases and protein-protein interactions and designing new ways to inhibit them in human diseases. Neel Ghosh is also a co-founder and Chief Scientific Officer for Luceome Biotechnologies. Neel received his doctoral degree in 1998 while working with Professor Jean Chmielewski at Purdue University. His doctoral research focused on designing inhibitors of protein-protein interactions and self-replicating peptides. In 1998 he joined Professor Andrew Hamilton and Professor Lynne Regan’s laboratories at Yale University as a joint postdoctoral fellow. At Yale, he discovered the first conditional split-Green Fluorescent Protein, which has been used as a means for measuring protein-protein interactions by many laboratories and the methodology is sometimes called fluorescent protein complementation. In 2001, Neel Ghosh joined the Department of Chemistry and Biochemistry at the University of Arizona as an Assistant Professor and was promoted to Associate Professor and then to the Davis & Weed Chair and Full Professor in 2011. Keywords: Chemistry, Biochemistry, Biomedical Engineering, Cancer

Publications

Zhou, M., Bentley, D., & Ghosh, . (2005). Helical supramolecules and fibers utilizing leucine zipper-displaying dendrimers. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 126(3), 734-735.
Yongsheng, M. a., Cunningham, M. E., Wang, X., Ghosh, I., Regan, L., & Longley, B. J. (1999). Inhibition of spontaneous receptor phosphorylation by residues in a putative α-helix in the KIT intracellular juxtamembrane region. Journal of Biological Chemistry, 274(19), 13399-13402.

PMID: 10224103;Abstract:

KIT receptor kinase activity is repressed, prior to stem cell factor binding, by unknown structural constraints. Using site-directed mutagenesis, we examined the role of KIT intracellular juxtamembrane residues Met-552 through Ile-563 in controlling receptor autophosphorylation. Alanine substitution for Tyr-553, Trp557, Val-559, or Val-560, all sitting along the hydrophobic side of an amphipathic α-helix (Tyr-553-Ile-563) predicted by the Chou-Fasman algorithm, resulted in substantially increased spontaneous receptor phosphorylation, revealing inhibitory roles for these residues. Alanine substitution for other residues, most of which are on the hydrophilic side of the helix, caused no or slightly increased basal receptor phosphorylation. Converting Tyr-553 or Trp-557 to phenylalanine generated slight or no elevation, respectively, in basal KIT phosphorylation, indicating that the phenyl ring of Tyr-553 and the hydrophobicity of Trp-557 are critical for the inhibition. Although alanine substitution for Lys-558 had no effect on receptor phosphorylation, its substitution with proline produced high spontaneous receptor phosphorylation, suggesting that the predicted α-helical conformation is involved in the inhibition. A synthetic peptide comprising Tyr-553 through Ile-563 showed circular dichroism spectra characteristic of α-helix, supporting the structural prediction. Thus, the KIT intracellular juxtamembrane region contains important residues which, in a putative α-helical conformation, exert inhibitory control on the kinase activity of ligand-unoccupied receptor.

Magliery, T. J., G., C., Pan, W., Mishler, D., Ghosh, I., Hamilton, A. D., & Regan, L. (2005). Detecting protein-protein interactions with a green fluorescent protein fragment reassembly trap: Scope and mechanism. Journal of the American Chemical Society, 127(1), 146-157.

PMID: 15631464;Abstract:

Identification of protein binding partners is one of the key challenges of proteomics. We recently introduced a screen for detecting protein-protein interactions based on reassembly of dissected fragments of green fluorescent protein fused to interacting peptides. Here, we present a set of comaintained Escherichia coli plasmids for the facile subcloning of fusions to the green fluorescent protein fragments. Using a library of antiparallel leucine zippers, we have shown that the screen can detect very weak interactions (KD ≈ 1 mM). In vitro kinetics show that the reassembly reaction is essentially irreversible, suggesting that the screen may be useful for detecting transient interactions. Finally, we used the screen to discriminate cognate from noncognate protein-ligand interactions for tetratricopeptide repeat domains. These experiments demonstrate the general utility of the screen for larger proteins and elucidate mechanistic details to guide the further use of this screen in proteomic analysis. Additionally, this work gives insight into the positional inequivalence of stabilizing interactions in antiparallel coiled coils.

Ghosh, I., Rajagopal, S., Meyer, S. C., Goldman, A., Zhou, M., & Ghosh, I. -. (2006). A minimalist approach toward protein recognition by epitope transfer from functionally evolved beta-sheet surfaces. Journal of the American Chemical Society, 128(44).

New approaches for identifying small molecules that specifically target protein surfaces as opposed to active site clefts are of much current interest. Toward this goal, we describe a three-step methodology: in step one, we target a protein of interest by directed evolution of a small beta-sheet scaffold; in step two, we identify residues on the scaffold that are implicated in binding; and in step three, we transfer the chemical information from the beta-sheet to a small molecule mimic. As a case study, we targeted the proteolytic enzyme thrombin, involved in blood coagulation, utilizing a library of beta-sheet epitopes displayed on phage that were previously selected for conservation of structure. We found that the thrombin-binding, beta-sheet displaying mini-proteins retained their structure and stability while inhibiting thrombin at low micromolar inhibition constants. A conserved dityrosine recognition motif separated by 9.2 A was found to be common among the mini-protein inhibitors and was further verified by alanine scanning. A molecule containing two tyrosine residues separated by a linker that matched the spacing on the beta-sheet scaffold inhibited thrombin, whereas a similar dityrosine molecule separated by a shorter 6 A linker could not. Moreover, kinetic analysis revealed that both the mini-protein as well as its minimalist mimic with only two functional residues exhibited noncompetitive inhibition of thrombin. Thus, this reductionist approach affords a simple methodology for transferring information from structured protein scaffolds to yield small molecule leads for targeting protein surfaces with novel mechanisms of action.

Ghosh, I., Cox, K. J., Shomin, C. D., & Ghosh, I. -. (2011). Tinkering outside the kinase ATP box: allosteric (type IV) and bivalent (type V) inhibitors of protein kinases. Future medicinal chemistry, 3(1).

Many members of the protein kinase family have emerged as key targets for pharmacological intervention, most notably in cancer. However, the high sequence and structural homology shared by the more than 500 human protein kinases renders it exceedingly difficult to develop selective inhibitors. Most, if not all, existing inhibitors target multiple protein kinases. Current paradigm suggests that an inhibitor that targets multiple kinases and displays polypharmacology is not only acceptable but also often desirable as a therapeutic agent. However, as we move toward personalized medicine the currently acceptable promiscuity is likely to pose significant hurdles in terms of their therapeutic index, especially for diseases that necessitate long-term drug administration. Moreover, selective inhibitors are the only pharmacologically relevant route toward reagents for the dissection of complex signal transduction pathways. This article provides an overview of recent developments in the design of kinase inhibitors that display increasing selectivity by targeting regions outside the highly conserved ATP-binding pocket. These new approaches may pave the way to potentially new avenues for drug discovery while providing valuable tools for studying signal transduction.