PDBsum entry 2ic2

Protein binding

PDB id: 2ic2

Contents

Protein chains

104 a.a. *

114 a.a. *

Ligands

SO4 ×7

Waters ×208

* Residue conservation analysis

PDB id:

2ic2

Name:

Protein binding

Title:

Crystal structure of the first fniii domain of ihog

Structure:

Cg9211-pa. Chain: a, b. Fragment: first fniii domain. Synonym: gh03927p. Engineered: yes

Source:

Drosophila melanogaster. Fruit fly. Organism_taxid: 7227. Gene: ihog, cg9211. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.30Å R-factor: 0.215 R-free: 0.234

Authors:

J.S.Mclellan,D.J.Leahy

Key ref:

J.S.McLellan et al. (2006). Structure of a heparin-dependent complex of Hedgehog and Ihog. Proc Natl Acad Sci U S A, 103, 17208-17213. PubMed id: 17077139 DOI: 10.1073/pnas.0606738103

Date:

12-Sep-06 Release date: 24-Oct-06

Protein chain

Q9VM64  (IHOG_DROME) -  Interference hedgehog from Drosophila melanogaster

Seq: 886 a.a.

Struc: 104 a.a.*

Protein chain

Q9VM64  (IHOG_DROME) -  Interference hedgehog from Drosophila melanogaster

Seq: 886 a.a.

Struc: 114 a.a.*

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

DOI no: 10.1073/pnas.0606738103

Proc Natl Acad Sci U S A 103:17208-17213 (2006)

PubMed id: 17077139

Structure of a heparin-dependent complex of Hedgehog and Ihog.

J.S.McLellan, S.Yao, X.Zheng, B.V.Geisbrecht, R.Ghirlando, P.A.Beachy, D.J.Leahy.

ABSTRACT

Hedgehog (Hh) signaling molecules mediate key tissue-patterning events during animal development, and inappropriate activation of Hh signaling in adults has been associated with human cancers. Recently, a conserved family of type I integral membrane proteins required for normal response to the Hh signal was discovered. One member of this family, Ihog (interference hedgehog), functions upstream or at the level of Patched (Ptc), but how Ihog participates in Hh signaling remains unclear. Here, we show that heparin binding induces Ihog dimerization and is required to mediate high-affinity interactions between Ihog and Hh. We also present crystal structures of a Hh-binding fragment of Ihog, both alone and complexed with Hh. Heparin is not well ordered in these structures, but a basic cleft in the first FNIII domain of Ihog (IhogFn1) is shown by mutagenesis to mediate heparin binding. These results establish that Hh directly binds Ihog and provide the first demonstration of a specific role for heparin in Hh responsiveness.

Selected figure(s)

Figure 1.
Fig. 1. IhogFn1–2 adopts a horseshoe-like structure. (A) Ribbon diagram of IhogFn1–2. IhogFn1 is colored green, and IhogFn2 is colored light blue. A disordered loop is indicated by the dashed line. (B) An electrostatic potential surface of IhogFn1–2, shown in the same orientation as in A. The scale is calibrated to –12 kT/e and +12 kT/e for red and blue, respectively. Three sulfate ions are shown as orange and red sticks. All structure images were generated with PyMOL (http://pymol.sourceforge.net).

Figure 3.
Fig. 3. HhN binds to a cleft on IhogFn1. (A) Semitransparent molecular surface of the HhN/IhogFn1–2 complex superimposed on a ribbon diagram of the molecules. HhN is colored yellow, IhogFn1 is green, and IhogFn2 is light blue. The four residues that when mutated lead to loss of heparin binding are colored dark blue. (B) Electrostatic potential surface of the HhN/IhogFn1–2 complex, shown in the same orientation as in A. The black dotted line marks the boundary between HhN and IhogFn1–2. The four residues that when mutated lead to loss of heparin binding are outlined with white dashes. The color scale is calibrated to –12 kT/e and +12 kT/e for red and blue, respectively. (C) HhN/IhogFn1–2 interface. The four Hh residues mutated in the HhN/Ihog-interface 1 mutant are represented as balls and sticks, as are nearby IhogFn1–2 residues. Bridging waters are represented by red spheres and hydrogen bonds are shown as dashed lines. (D) Effects of HhN-interface mutations on HhN binding to Ihog-expressing Drosophila cultured cells.

Figures were selected by an automated process.