Postdoctoral Researcher, University of Florida
Ph.D., University of Tennessee (2001)
Protein sorting, protein transport, protein-protein interactions, membrane protein structure/function, and organelle biogenesis
My research focus is protein sorting within cells. We investigate mechanisms of protein transport as it relates to organelle biogenesis. Our research utilizes biochemical and biophysical approaches to cell biology in organello and in vitro, as well as whole cell approaches in vivo.
We focus our studies on chloroplasts and mitochondria from plant cells. Most proteins found in those organelles are encoded by genomic DNA and are synthesized in the cytoplasm as higher molecular weight precursor proteins which must cross membranes in order to get to their site of function. Survival of the plant and proper development of the organelle depend upon accurate sorting of proteins to their correct sub-organellar location.
We study a recently discovered system that transports fully folded proteins into the thylakoid lumen using only the thylakoid proton motive force as energy source. We also study the homologous system in mitochondria which likely transports proteins from the matrix to the inner membrane space. This system, the Tat system (Twin Arginine Transport), presents an intriguing and challenging mechanistic problem because it transports folded domains of varying diameters without rendering the membrane leaky to protons and ions.
Tat systems are now known to be widely present in bacteria and archaea as well as in the prokaryote-derived organelles: chloroplasts and plant mitochondria. However Tat systems are not found in animal cells. Thus they are likely to operate by ancient and possibly simple mechanisms, an enticing system for in vitro and reconstitution analysis. Tat systems may also be important targets for antimicrobial agents because they are involved in secretion of virulence factors for animal and plant diseases. For example, several human pathogens, such as Pseudomonas aeruginosa, Yersinia pseudotuberculosis, and Legionella pneumophila and at least one agriculturally significant pathogen, P. syringae pv. Tomato DC3000, require a functional Tat system to be virulent. Understanding the mechanism of protein transport by this system may provide new approaches to combating bacterial infections.
Zhou A, Abu-Baker S, Sahu ID, Liu L, McCarrick RM, Dabney-Smith C, Lorigan GA. 2012. Determining α -helical and β-sheet Secondary Structures via Pulsed EPR Spectroscopy. Biochemistry 51:7417-7419. doi:10.1021/bi3010736
Aldridge C, Storm A, Cline K, Dabney-Smith C. 2012. The Chloroplast Twin Arginine Transport (Tat) Component, Tha4, Undergoes Conformational Changes Leading to Tat Protein Transport. J Biol Chem 287:34752-34763. doi:10.1074/jbc.M112.385666
Holdorf MM, Owen HA, Lieber SR, Yuan L, Adams N, Dabney-Smith C, Makaroff, CA. 2012. Arabidopsis ETHE1 Encodes a Sulfur Dioxygenase That Is Essential for Embryo and Endosperm Development. Plant Physiol 160:226-236. doi:10.1104/pp.112.201855
Dabney-Smith, C. and Cline, K. 2009. Clustering of C-terminal stromal domains of Tha4 homo-oligomers during translocation by the Tat protein transport system. Mol Biol Cell 10.1091/mbc.E08-12-1189.
Cline, K. and C. Dabney-Smith. 2008. Plastid protein import and sorting: different paths to the same compartments. Curr Opin Plant Biol 11(6): 585-92.
Auldridge ME, Block A, Vogel JT, Dabney-Smith C, Mila I, Bouzayen M, Magallanes-Lundback M, DellaPenna D, McCarty DR, Klee HJ. 2006. Characterization of three members of the Arabidopsis carotenoid cleavage dioxygenase family demonstrates the divergent roles of this multifunctional enzyme family. Plant J 45(6):982-993.
Dabney-Smith, C; Mori, H; and Cline K. 2006. Oligomers of Tha4 organize at the thylakoid Tat translocase during protein transport. J Biol Chem 281:5476-5483.
Dabney-Smith, C; Mori, H; and Cline, K. 2003. Requirement of a Tha4 conserved transmembrane glutamate in thylakoid Tat translocase assembly revealed by biochemical complementation. J Biol Chem 278:43027-43033.
Fincher, V; Dabney-Smith, C; and Cline, K. 2003. Functional Assembly of Thylakoid ΔpH-Dependent/Tat Protein Transport Pathway Components In Vitro. J Biol Chem 270:4930-4941.
Schleiff, E; Sveshnikova, N, Tien, R, Soll, J, Wright, S, Dabney-Smith, C, Subramanian, C, and Bruce, BD. 2002. Structural and nucleotide requirements for transit peptide recognition by the chloroplast translocation machinery and the cytosolic domain of the receptor, Toc34. Biochemistry 41:1934-1946.
Lee, SK; Dabney-Smith, C; Hacker, D; and Bruce, BD. 2001. Interaction of the southern cowpea mosaic virus coat protein with membranes. Virology 291:299-310.
Dabney-Smith, C; van den Wijngaard, PW; Treece, Y; Vredenberg, W; and Bruce, BD. 1999. The C-terminus of a chloroplast precursor modulates its interaction with the translocation apparatus. J Biol Chem 274:32351-32359.
van den Wijngaard, PW; Dabney-Smith, C; Bruce, BD; and Vredenberg, WJ. 1999. The mechanism of inactivation of a 50-Picosiemens envelope anion channel during chloroplast protein import. Biophysical Journal 77:3156-3162.