Head and Professor
Office: Hesler, 133: (865-974-4070)
Lab: Hesler, 135-136: (865-974-2364, -2339)
Ph.D. 1983, Biochemistry and Biophysics, The University of California, Davis
The evolution of land plants has led to a diversification of multiple gene families of membrane transport, pump and channel proteins that orchestrate the uptake, transport and partitioning of numerous small molecule substrates spanning the range from critical nutrients to stress metabolites to water. My laboratory is broadly interested in the integral membrane transport proteins that mediate these transport phenomena in response to metabolic need and environmental stress adaptation. We investigate the properties of these proteins across scales, from the elucidation of the mechanisms of transport and permeation by biophysical and structural approaches, to the investigation of their biological functions at the cellular and organismal levels. Additional lab interests also involve the investigation of the structure and biological function of calcium-regulatory targets of the calmodulin superfamily. Recent specific areas of interest include: 1. The investigation of transporters, ion channels and aquaporins in the symbiosome membrane, the interface between legume and rhizobia nitrogen-fixing symbioses; 2. The diversification of the structure and function of aquaporin and aquaporin-like channels in higher plants; and 3. The role of calmodulin-like proteins as regulators of RNA dynamics during plant stress responses.
Left, expression profile of the aquaporin-like boron transporter NIP7-1 in developing Arabidopsis flower anthers; Right, topology and structural model of NIP7;1 highlighting the role of tyrosine residues in gating of the pore pathway.
W.G. Choi and D.M. Roberts (2007) Arabidopsis NIP2;1: a major intrinsic protein transporter of lactic acid induced by anoxic stress. J. Biol. Chem. 282, 24209-24218.
M. Tanaka, I.S. Wallace, J. Takano, D.M. Roberts, and T. Fugiwara (2008) NIP6;1 Is a Boric Acid Channel for Preferential Transport of Boron to Growing Shoot Tissues in Arabidopsis thaliana. Plant Cell, 20, 2860-2875.
P. Masalkar, I.S. Wallace, J.H. Hwang, and D.M. Roberts (2010) Interaction of cytosolic glutamine synthetase with the nodulin 26 channel on the soybean symbiosome membrane. J. Biol. Chem. 285, 23880-23888.
J.H. Hwang, S.R. Ellingson, and D.M. Roberts (2010) Ammonia permeability of the soybean nodulin 26 channel. FEBS Lett. 484, 4339-4343.
T. Li, W.G. Choi, I.S. Wallace, J. Baudry, and D.M. Roberts (2011) Arabidopsis thaliana NIP7;1: an anther-specific boric acid transporter of the aquaporin superfamily regulated by an unusual tyrosine in helix 2 of the transport pore. Biochemistry 50, 6633-6641.
I.S. Wallace, A.J. Shakesby, J.H. Hwang, A.E. Douglas, and D.M. Roberts (2012) Acyrthosiphon pisum AQP2 is a multifunctional aquaglyceroporin expressed in bacteriocyte tissue. Biochim. Biophys. Acta Biomembranes 1818, 627-635.