Robert J Keenan
Research Summary / Selected Publications
Our research interfaces biology and chemistry to understand the
molecular mechanisms that underlie fundamental biological processes. Current research topics include:
1. Membrane protein biogenesis. How do newly synthesized membrane (and secretory) proteins reach the membrane? Once there, how are they inserted into (or translocated across) the membrane? A major focus in the lab is the study of co- and post-translational targeting and insertion pathways using a combination of structural, biochemical and genetic approaches. Our long-term goal is to decipher common structural and mechanistic themes in membrane protein biogenesis.
2. Protein evolution. How do proteins evolve new functions? Directed evolution is a powerful strategy for engineering proteins with new and optimized activities, and it offers a unique approach to study the molecular mechanisms that underlie the evolutionary process. We study molecular evolution in fluorescent proteins (FPs) using a combination of directed evolution, structural and biochemical analysis, and we use this information to engineer FPs for a variety of biomedical imaging applications. We also study protein evolution in members of the N-acetyltransferase superfamily, which perform a wide range of important functions ranging from gene regulation to antibiotic and herbicide resistance.
Our research interfaces biology and chemistry to understand the
molecular mechanisms that underlie fundamental biological processes. Current research topics include:
1. Membrane protein biogenesis. How do newly synthesized membrane (and secretory) proteins reach the membrane? Once there, how are they inserted into (or translocated across) the membrane? A major focus in the lab is the study of co- and post-translational targeting and insertion pathways using a combination of structural, biochemical and genetic approaches. Our long-term goal is to decipher common structural and mechanistic themes in membrane protein biogenesis.
2. Protein evolution. How do proteins evolve new functions? Directed evolution is a powerful strategy for engineering proteins with new and optimized activities, and it offers a unique approach to study the molecular mechanisms that underlie the evolutionary process. We study molecular evolution in fluorescent proteins (FPs) using a combination of directed evolution, structural and biochemical analysis, and we use this information to engineer FPs for a variety of biomedical imaging applications. We also study protein evolution in members of the N-acetyltransferase superfamily,...
Hegde, R.S. and Keenan, R.J. (2011). Tail-anchored membrane protein insertion into the endoplasmic reticulum. Nat. Rev. Mol. Cell Biol., 12:787-798.; advance online publication (doi:10.1038/nrm3226).
Mariappan, M.*, Mateja, A.*, Dobosz, M., Bove, E., Hegde, R.S. and Keenan, R.J. (2011) The mechanism of membrane-associated steps in tail-anchored protein insertion. Nature, 477:61-65; advance online publication, (doi:10.1038/nature10362).
Sherrill, J., Mariappan, M., Dominik, P., Hegde, R.S. and Keenan, R.J., (2011) A conserved archaeal pathway for tail-anchored membrane protein insertion. Traffic, 12:1119-1123.
Strack, R.L., Strongin, D.E., Mets, L., Glick, B.S. and Keenan, R.J. (2010) Chromophore formation in DsRed occurs by a branched pathway. J. Am. Chem. Soc., 132:8496-8505.
Mateja, A., Szlachcic, A., Downing, M.E., Dobosz, M., Mariappan, M., Hegde, R.S. and Keenan, R.J. (2009) The structural basis of tail-anchored membrane protein recognition by Get3. Nature, 461:361-366; advance online publication, (doi:10.1038/nature08319).
Strack, R.L., Strongin, D.E., Bhattacharyya, D., Tao, W., Berman, A., Broxmeyer, H.E., Keenan, R.J. and Glick, B.S. (2008) A noncytotoxic DsRed variant for whole-cell labeling. Nature Methods, 5:955-957.
Keenan, R.J., Siehl, D.L., Gorton, R. and Castle, L.A. (2005). DNA shuffling as a tool for protein crystallization. Proc Natl Acad Sci USA, 102:8887-8892.
Keenan, R.J., Freymann, D.M., Stroud, R.M. and Walter, P. (2001). The Signal Recognition Particle. Annu. Rev. Biochem., 70:755-775.
Keenan, R.J., Freymann, D.M., Walter, P. and Stroud, R.M. (1998). Crystal Structure of the Signal Sequence Binding Subunit of the Signal Recognition Particle. Cell, 94:181-191.
Freymann, D.M., Keenan, R.J., Stroud, R.M. and Walter, P. (1997). Structure of the conserved GTPase domain of the signal recognition particle. Nature, 385:361-364.
Hegde, R.S. and Keenan, R.J. (2011). Tail-anchored membrane protein insertion into the endoplasmic reticulum. Nat. Rev. Mol. Cell Biol., 12:787-798.; advance online publication (doi:10.1038/nrm3226).
Mariappan, M.*, Mateja, A.*, Dobosz, M., Bove, E., Hegde, R.S. and Keenan, R.J. (2011) The mechanism of membrane-associated steps in tail-anchored protein insertion. Nature, 477:61-65; advance online publication, (doi:10.1038/nature10362).
Sherrill, J., Mariappan, M., Dominik, P., Hegde, R.S. and Keenan, R.J., (2011) A conserved archaeal pathway for tail-anchored membrane protein insertion. Traffic, 12:1119-1123.
Strack, R.L., Strongin, D.E., Mets, L., Glick, B.S. and Keenan, R.J. (2010) Chromophore formation in DsRed occurs by a branched pathway. J. Am. Chem. Soc., 132:8496-8505.
Mateja, A., Szlachcic, A., Downing, M.E., Dobosz, M., Mariappan, M., Hegde, R.S. and Keenan, R.J. (2009) The structural basis of tail-anchored membrane protein recognition by Get3. Nature, 461:361-366; advance online publication, (doi:10.1038/nature08319).
