PDBsum entry 1mc7

Signaling protein

PDB id

1mc7

Contents

			Protein chain

					95 a.a. *

* Residue conservation analysis

References listed in PDB file

Key reference

Title

Direct binding of the pdz domain of dishevelled to a conserved internal sequence in the c-Terminal region of frizzled.

Authors

H.C.Wong, A.Bourdelas, A.Krauss, H.J.Lee, Y.Shao, D.Wu, M.Mlodzik, D.L.Shi, J.Zheng.

Ref.

Mol Cell, 2003, 12, 1251-1260. [DOI no: 10.1016/S1097-2765(03)00427-1]

PubMed id

14636582

Abstract

The cytoplasmic protein Dishevelled (Dvl) and the associated membrane-bound receptor Frizzled (Fz) are essential in canonical and noncanonical Wnt signaling pathways. However, the molecular mechanisms underlying this signaling are not well understood. By using NMR spectroscopy, we determined that an internal sequence of Fz binds to the conventional peptide binding site in the PDZ domain of Dvl; this type of site typically binds to C-terminal binding motifs. The C-terminal region of the Dvl inhibitor Dapper (Dpr) and Frodo bound to the same site. In Xenopus, Dvl binding peptides of Fz and Dpr/Frodo inhibited canonical Wnt signaling and blocked Wnt-induced secondary axis formation in a dose-dependent manner, but did not block noncanonical Wnt signaling mediated by the DEP domain. Together, our results identify a missing molecular connection within the Wnt pathway. Differences in the binding affinity of the Dvl PDZ domain and its binding partners may be important in regulating signal transduction by Dvl.



	Figure 2. Figure 2. Interaction between the mDvl1 PDZ Domain and Fz7(A) ^15N-HSQC spectra of free Fz7 peptide and Fz7 peptide bound to the PDZ domain of mDvl1. The red contour lines represent spectra of the free form of the PDZ domain when no Fz7 peptide (GKTLQSWRRFYH) was present, the green lines (upper inset) represent spectra of partially bound forms of the PDZ domain when 0.86 mM Fz7 peptide was present, and the blue lines represent spectra of the fully bound forms of the PDZ domain when 10 mM Fz7 peptide was present. The concentration of the PDZ domain was 1.1 mM. The two insets show the enlarged regions where the chemical-shift perturbations were small (lower inset) and large (upper inset). In the upper inset, the signals from the same residue but in different spectra were placed in smaller boxes.(B) The figure shows the worm representation of the backbone structure of the mDvl1 PDZ domain. The thickness of the worm is proportional to the weighted sum (in Hz) of the ^1H and ^15N shifts upon binding by the Fz7 peptide (see A), and the increasing chemical-shift perturbation is shown (blue, low; red, high).(C) Ribbon diagram of the PDZ domain structure. The binding site of the Fz7 peptide identified from the chemical-shift perturbation studies is indicated.		Figure 3. Figure 3. Fz7 and Dpr/Frodo Peptides and Their Binding to the PDZ Domain In Vitro(A) Biotinylated Fz7 or Dpr/Frodo peptide was coupled to the UltraLink Immobilized Monomeric Avidin, and the avidin-coupled peptides were then incubated with purified PDZ domain. After extensive washing, peptide-interacting proteins were resolved and visualized by SDS-PAGE. Besides those bound to the PDZ domain, some proteins that became detached from the avidin-immobilized beads were also observed. Lane 1, marker. Lane 2, PDZ domain. Lane 3, The PDZ domain and the avidin-agarose beads. Lane 4, The PDZ domain and beads coupled to the Fz7 peptide. Lane 5, the PDZ domain and beads coupled to the Dpr/Frodo peptide. Lane 6: the PDZ domain bound to the Fz7 peptide-coupled beads after elution by the Dpr/Frodo peptide. The experimental condition was similar to that used for the mixture depicted in lane 4, except that before SDS-PAGE, the beads were washed with a buffer that contained Dpr/Frodo peptide.

PROCHECK

	Headers