Protein-Protein Interactions in Cell Signaling of small GTPases, Plexin and Eph receptors
We characterize protein-protein interactions and seek to determine how they form the molecular basis of mechanisms in cell signaling. For these studies, we use a range of structural biology, computational as well as biophysics tools, and we also collaborate with cell biologists. Both the structure and dynamics of signaling proteins are important for signal transduction. We want to understand their molecular determinants and thus their role; for example, what protein structural and dynamic features give rise to binding affinity and to the specificity that selects one protein binding partner over others? These studies will allow give us insight into the normal functions of the signaling proteins and how they are disrupted in diseased states. The knowledge gained will also help us in screening for small molecule agents that can be used to manipulate protein-protein interactions (and consequently signaling in cells) in a chemical biology approach. Furthermore, we develop methods that assist in the identification of interactions in protein complexes and improve their structural representation and characterization by molecular dynamics calculations. Of late our focus has expanded to include the transmembrane helices of receptors. We are interested in understanding how signals are transmitted across the cellular membrane via the receptor’s transmembrane helices and what role the protein domain - bilayer interactions play in the process.
- Tong Y, P Chugha, PK Hota, RS Alviani, M Li, W Tempel, L Shen, HW Park & M Buck. Binding of Rac1, Rnd1, and RhoD to a novel Rho GTPase interaction motif destabilizes dimerization of the plexin-B1 effector domain. J. Biol. Chem. 282:37215-24, 2007.
- Bouguet-Bonnet S & M Buck. Compensatory and long-range changes in picosecond-nanosecond main-chain dynamics upon complex formation: 15N relaxation analysis of the free and bound states of the ubiquitin-like domain of human plexin-B1 and the small GTPase Rac1. J. Mol. Biol. 377:1474-87, 2008.
- Tong Y, PK Hota, JY Penachioni, MB Hamaneh, S Kim, RS Alviani, L Shen, H He, W Tempel, L Tamagnone, HW Park & M Buck. Structure and function of the intracellular region of the plexin-b1 transmembrane receptor. J. Biol. Chem. 284:35962-72, 2009.
- Lee HJ, PK Hota, P Chugha, H Guo, H Miao, L Zhang, SJ Kim, L Stetzik, BC Wang & M Buck. NMR structure of a heterodimeric SAM:SAM complex: characterization and manipulation of EphA2 binding reveal new cellular functions of SHIP2. Structure 20:41-55, 2012.
- Hota PK & M Buck. Plexin structures are coming: opportunities for multilevel investigations of semaphorin guidance receptors, their cell signaling mechanisms, and functions. Cell. Mol. Life Sci. 69:3765-805, 2012.
- Zhang L, A Polyansky & M Buck. Modeling transmembrane domain dimers/trimers of plexin receptors: implications for mechanisms of signal transmission across the membrane. PLoS ONE 10:e0121513, 2015.