PDBsum entry 2qk2

Protein binding

PDB id: 2qk2

Contents

Protein chain

241 a.a. *

Waters ×161

* Residue conservation analysis

PDB id:

2qk2

Name:

Protein binding

Title:

Structural basis of microtubule plus end tracking by xmap215, clip-170 and eb1

Structure:

Lp04448p. Chain: a. Fragment: tog domain 2. Engineered: yes

Source:

Drosophila melanogaster. Fruit fly. Organism_taxid: 7227. Gene: msps. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.10Å R-factor: 0.202 R-free: 0.217

Authors:

K.C.Slep,R.D.Vale

Key ref:

K.C.Slep and R.D.Vale (2007). Structural Basis of Microtubule Plus End Tracking by XMAP215, CLIP-170, and EB1. Mol Cell, 27, 976-991. PubMed id: 17889670 DOI: 10.1016/j.molcel.2007.07.023

Date:

10-Jul-07 Release date: 02-Oct-07

Protein chain

Q9VEZ3  (MSPS_DROME) -  Protein mini spindles from Drosophila melanogaster

Seq: 2042 a.a.

Struc: 241 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

DOI no: 10.1016/j.molcel.2007.07.023

Mol Cell 27:976-991 (2007)

PubMed id: 17889670

Structural Basis of Microtubule Plus End Tracking by XMAP215, CLIP-170, and EB1.

K.C.Slep, R.D.Vale.

ABSTRACT

Microtubule plus end binding proteins (+TIPs) localize to the dynamic plus ends of microtubules, where they stimulate microtubule growth and recruit signaling molecules. Three main +TIP classes have been identified (XMAP215, EB1, and CLIP-170), but whether they act upon microtubule plus ends through a similar mechanism has not been resolved. Here, we report crystal structures of the tubulin binding domains of XMAP215 (yeast Stu2p and Drosophila Msps), EB1 (yeast Bim1p and human EB1), and CLIP-170 (human), which reveal diverse tubulin binding interfaces. Functional studies, however, reveal a common property that native or artificial dimerization of tubulin binding domains (including chemically induced heterodimers of EB1 and CLIP-170) induces tubulin nucleation/assembly in vitro and, in most cases, plus end tracking in living cells. We propose that +TIPs, although diverse in structure, share a common property of multimerizing tubulin, thus acting as polymerization chaperones that aid in subunit addition to the microtubule plus end.

Selected figure(s)

Figure 3.
Figure 3. Structure of the Second TOG Domains from Mini Spindles and Stu2p
Ribbon diagram of the TOG2 domain from Msps (A) and Stu2p (B) with the six HEAT-like repeats represented in shades of similar color and labeled A–F. The conserved and nonconserved regions (faces A and B, respectively) are indicated. (C) Least-squares fit of Msps (color) and Stu2p (gray) with TOG2 domains shown in cylindrical helix representation. (D) Individual TOG2 HEAT-like repeats are shown for Msps and Stu2p in ribbons format in similar orientations after global least-squares fit of each TOG2 domain. The definitive α helix kink that defines HEAT repeats is evident in the α2 helices of Msps HEAT-like repeats C and D and Stu2p HEAT-like repeats C and F. (E) 90° rotations of the Msps TOG2 domain about its long axis shown at left in ribbons for orientation and at right in CPK representation for conservation mapping. TOG2 residues with 80% identity across species are represented in green, 80% conservation in yellow (see Figure S2). (E) 2F[o] − F[c] electron density map at 1.7 Å resolution of the Stu2p TOG2 structure contoured at 1.0 σ showing the surface exposed and highly conserved KEKK loop of HEAT-like repeat C. (G) 2F[o] − F[c] electron density map at 2.1 Å resolution of the Msps TOG2 structure contoured at 1.0 σ showing the surface exposed W292 residue and the buried R295-D331 salt bridge. Inset (upper left) indicates the relative orientation of the TOG domain (F and G). (H) Gel filtration tubulin binding assays for wild-type (WT) and mutant Msps TOG1-2. Single or double mutations of the conserved TOG domain tryptophan (TOG1: W21E, TOG2: W292E) are indicated above the chromatogram. Tubulin alone, black; Msps TOG1-2 WT alone, red. The plot indicates absorption at 280 nm on the y axis (mAU) and elution volume in ml along the x axis.

Figure 4.
Figure 4. Structure of the Calponin Homology Domains of EB1 and Bim1p
Ribbon diagram of the N-terminal CH domain from EB1 (A) and Bim1p (B) centered on the highly conserved α6 helix. (C) Least-squares fit of EB1 (color) and Bim1p (gray) CH domains with cylindrical helix representation showing the overall structural conservation between these two members. (D) 2F[o] − F[c] electron density map at 1.25 Å resolution of the EB1 CH domain structure contoured at 1.0 σ showing the highly conserved aromatic core. (E) Ninety degrees rotation of the EB1 CH domain about the y axis shown above in ribbon format for orientation and below in CPK representation for conservation mapping and to summarize mutagenesis results. Center: CH domain residues with 80% identity across species are represented in green, 80% conservation in yellow (D and E) (see Figure S3). Bottom row: results of CH domain mutagenesis on the ability of EB1[1–187]-LZ to plus end track are mapped. Ablation of microtubule association, brick red (three cluster mutants indicated: [S16A, R17E, H18E, D19R], [K59E, K60E], and [K66E, L67D]). No effect on microtubule plus end tracking, slate.

The above figures are reprinted from an Open Access publication published by Cell Press: Mol Cell (2007, 27, 976-991) copyright 2007.

Figures were selected by an automated process.