RESEARCH:

Heterotrimeric G-protein mediated cellular signal transduction pathway is the dominant mode of transducing extracellular signal inside the cell. Although the presence of G-protein coupled signal transduction is well documented in diverse biological systems, evidence for a comparable system in plants has just started to accumulate. By utilizing G-protein knock-out alleles in Arabidopsis, our previous works have unraveled diverse G-protein dependent signaling pathways, ranging from auxin, brassinosteroid, gibberellin, ABA, and water-stress.

At present, my lab is interested in elucidating the cellular signal transduction pathways mediated by Receptor for Activated Kinase C (RACK1)- a structural homolog of G-protein beta subunit. Major function of RACK1 is perceived to be the integration of signals from different pathways by acting as a scaffold protein. The repertoire of non-plant RACK1 interacting proteins that contain diverse partners ranging from kinases, phosphatases, heterotrimeric G-proteins, ion channels, ribosomes, and membrane and nuclear receptors, established the protein as a multipurpose protein. Though three distinct RACK1 genes, as opposed to a single gene in non-plant organisms, are present in Arabidopsis, essentially nothing is known about their cellular functions. A combination of molecular genetic and cell biological approaches are being utilized to unravel the plant RACK1-mediated signaling pathways. Preliminary results from gene knock-out characterizations implicate RACK1 in plant signaling pathways that are not present in other organisms. Therefore, plant RACK1 studies provide unique opportunities to unravel novel roles for the protein.

TEACHING:

Molecular Biology of the Cell (Graduate Course)
Plant Physiology (Undergraduate Course)

RECENT PUBLICATIONS:

Ullah, H., Scappini, E., Moon, AF., Williams, LV., Armstrong, DL., and Pedersen, LC (2008) Crystal Structure of a signal transduction regulator, RACK1, from Arabidopsis thaliana. Protein Sci 17(10):1771-80. (on cover page)

Magee, K., Michael, A., Ullah, H., and Dutta, SK. (2007) Dechlorination of PCB in the presence of plant nitrate reductase. Environmental Toxicology and Pharmacology 25:144-147.

Chen JG, Ullah H, Temple B, Liang J, Guo J, Alonso JM, Ecker JR, Jones AM. (2006) RACK1 mediates multiple hormone responsiveness and developmental processes in Arabidopsis. J Exp Bot, 57: 2697-2708.

Nina M. Storey, NM., Gentile, S., Ullah, H.,Russo, A., Muessel, M., Erxleben, C., and Armstrong, DL. (2006) Rapid signaling at the plasma membrane by a nuclear receptor for thyroid hormone. Proceedings of the National Academy of Sciences, USA. 103: 5197-5201.

Ullah H, Chen JG, Temple B, Alonso J, Ecker J, Boyes D, Davis K, and Jones AM (2003) Auxin Signaling Coupled by Heterotrimeric G protein in Arabidopsis Lateral Root Formation. Plant Cell 15, 393-409.

Ullah H, Chen JG, and Jones AM (2002) Role of GPA1 in Regulation of Arabidopsis Seed Germination. Plant Physiology 129, 897-907.

Chen JG, Ullah H, Young JC, Sussman MR, Jones AM (2001) ABP1 is Required for Organized Cell Elongation and Division in Arabidopsis Embryogenesis. Genes & Development 15, 902-911 (On Cover Page)

Ullah H., Chen JG, Young JC, Im KH, Sussman MR, and Jones AM (2001) Modulation of Cell Proliferation by G-protein Alpha Subunit in Arabidopsis. Science 292, 2066-2069.

Ullah H, Clark G, and Islam AS (2001) Internet Resources for Molecular Biology: A Primer for Scientists from Least Developed Countries. Plant Tissue Cult. 11, 195-208, 2001.

Wang XQ, Ullah H, Jones AM, and Assmann S (2001) G protein Regulation of Ion Channels and Abscisic Acid Signaling in Arabidopsis Guard Cells. Science 292, 2070-2072.

BOOK CHAPTER

Jones AM, Ullah H, and Chen JG (2003) Dual Pathways for Auxin Regulate Cell Division and Expansion. ed. Nagata, T. Biotechnology in Agriculture and Forestry (Series), .Springer Press. Vol. 53, 181-191.