Xing Liu

Active Mentor - currently hosting PULSe students for laboratory rotations and recruiting PULSe students into the laboratory; serves on preliminary exam committees

Current Research Interests:

We are interested in understanding the mechanism of protein ubiquitination and how this post-translational modification determines proper cellular and organismal functions. To achieve this goal, we use human cells and plants as our experimental systems. Our current research focuses on the dynamics of Skp1•Cul1•F-box protein (SCF) ubiquitin E3 ligases, a group of enzymes that play critical roles in eukaryotic biology, ranging from cell division to organ formation. Each SCF has a core Cul1 protein that assembles with a family of F-box proteins to form different complexes with distinct substrate specificities. The genome of human and Arabidopsis thaliana encodes 69 and ~700 F-box proteins, respectively, each of which needs to assemble with Cul1 for the degradation of its substrates. Therefore, recruiting the right type of F-box protein at the right time in the right location is essential for proper SCF function. We aim to understand how the cellular repertoire of the SCF is dynamically controlled to meet the changing needs of substrates, applying multidisciplinary approaches such as biophysics, chemical genetics, genome editing, quantitative mass spectrometry, and computational modeling.

Selected Publications:

Liu X, Reitsma JM, Mamrosh JL, Zhang Y, Straube R, Deshaies RJ (2018) Cand1-mediated adaptive exchange mechanism enables variation in F-box protein expression. Mol Cell 69: 773-786 (Featured article)

Reitsma JM, Liu X, Reichermeier KM, Moradian A, Sweredoski MJ, Hess S, Deshaies RJ (2017) Composition and Regulation of the Cellular Repertoire of SCF Ubiquitin Ligases. Cell 171: 1326-1339

Zhou Y, Liu X, Engstrom EM, Nimchuk ZL, Pruneda-Paz JL, Tarr PT, Yan A, Kay SA, Meyerowitz EM (2015) Control of plant stem cell function by conserved interacting transcriptional regulators. Nature 517: 377-380

Pierce NW, Lee JE, Liu X, Sweredoski MJ, Graham RLJ, Larimore EA, Rome M, Zheng N, Clurman BE, Hess S, Shan SO, Deshaies RJ (2013) Cand1 promotes assembly of new SCF complexes through dynamic exchange of F-box proteins. Cell 153: 206-15

Li W, Zhou Y, Liu X, Yu P, Cohen JD, Meyerowitz EM (2013) LEAFY controls auxin response pathways in floral primordium formation. Science Signaling 6: ra23 Liu X, Wu J, Clark G, Lim M, Arnold D, Gardner G, Roux SJ (2012) Role for apyrases in polar auxin transport in Arabidopsis. Plant Physiology 160:1985-95

De Rybel B, Audenaert D, Xuan W, Overvoorde P, Strader LC, Kepinski S, Hoye R, Brisbois R, Parizot B, Vanneste S, Liu X, Gilday A, Graham IA, Nguyen L, Jansen L, Njo MF, Inzé D, Bartel B, Beeckman T (2012) A role for the root cap in root branching revealed by the non-auxin probe naxillin. Nature Chemical Biology 8:798–805

Liu X*, Hegeman AD, Gardner G, Cohen JD (2012) Protocol: High-throughput and quantitative assays of auxin and auxin precursors from minute tissue samples. Plant Methods 8:31 (* Denotes corresponding author)

Liu X*, Barkawi LS, Gardner G, Cohen JD (2012) Transport of indole-3-butyric acid and indole-3-acetic acid in Arabidopsis thaliana hypocotyls using stable isotope labeling. Plant Physiology 158:1988-2000 (* Denotes corresponding author)

Liu X*, Cohen JD, Gardner G (2011) Low fluence red light increases the transport and biosynthesis of auxin. Plant Physiology 157:891-904 (* Denotes corresponding author)

Cheng NH, Liu JZ, Liu X, Wu Q, Thompson SM, Lin J, Chang J, Whitham SA, Park S, Cohen JD, Hirschi KD (2011) Arabidopsis monothiol glutaredoxin, AtGRXS17, is critical for temperature-dependent postembryonic growth and development via modulating auxin response. Journal of Biological Chemistry 286:20398-406

Phillips KA, Skirpan AL, Liu X, Christensen A, Slewinski TL, Hudson C, Barazesh S, Cohen JD, Malcomber S, McSteen P (2011) vanishing tassel 2 encodes a grass-specific tryptophan aminotransferase required for vegetative and reproductive development in maize. Plant Cell 23:550-66