title: Conformational change upon ligand binding and dynamics of the PDZ domain from leukemia-associated Rho guanine nucleotide exchange factor.
abstract: Leukemia-associated Rho guanine nucleotide exchange factor (LARG) is a RhoA-specific guanine nucleotide exchange factor (GEF) that can activate RhoA. The PDZ (PSD-95/Disc-large/ZO-1 homology) domain of LARG interacts with membrane receptors, which can relay extracellular signals to RhoA signal transduction pathways. Until now there is no structural and dynamic information about these interactions. Here we report the NMR structures of the LARG PDZ in the apo form and in complex with the plexin-B1 C-terminal octapeptide. Unobservable resonances of the residues in betaB/betaC and betaE/alphaB loops in apo state were observed in the complex state. A distinct region of the binding groove in the LARG PDZ was found to undergo conformational change compared with other PDZs. Analysis of the (15)N relaxation data using reduced spectral density mapping shows that the apo LARG PDZ (especially its ligand-binding groove) is flexible and exhibits internal motions on both picosecond to nanosecond and microsecond to millisecond timescales. Mutagenesis and thermodynamic studies indicate that the conformation of the betaB/betaC and betaE/alphaB loops affects the PDZ-peptide interaction. It is suggested that the conformational flexibility could facilitate the change of structures upon ligand binding.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
authors.forename: Jiangxin
authors.initials: J
authors.lastname: Liu
authors.forename: Jiahai
authors.initials: J
authors.lastname: Zhang
authors.forename: Yinshan
authors.initials: Y
authors.lastname: Yang
authors.forename: Hongda
authors.initials: H
authors.lastname: Huang
authors.forename: Weiqun
authors.initials: W
authors.lastname: Shen
authors.forename: Qi
authors.initials: Q
authors.lastname: Hu
authors.forename: Xingsheng
authors.initials: X
authors.lastname: Wang
authors.forename: Jihui
authors.initials: J
authors.lastname: Wu
authors.forename: Yunyu
authors.initials: Y
authors.lastname: Shi
mesh_terms: D000595:Amino Acid Sequence; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry* / Q000378:metabolism*; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D064067:Rho Guanine Nucleotide Exchange Factors; D017386:Sequence Homology, Amino Acid
chemical_list: C577222:ARHGEF12 protein, human; D020662:Guanine Nucleotide Exchange Factors; D008024:Ligands; D064067:Rho Guanine Nucleotide Exchange Factors