PDBsum entry 1yfq

Signaling protein

PDB id: 1yfq

Contents

Protein chain

342 a.a. *

Ligands

ACT

Metals

_CA ×4

Waters ×561

* Residue conservation analysis

PDB id:

1yfq

Name:

Signaling protein

Title:

High resolution s. Cerevisiae bub3 mitotic checkpoint protein

Structure:

Cell cycle arrest protein bub3. Chain: a. Engineered: yes

Source:

Saccharomyces cerevisiae. Baker's yeast. Organism_taxid: 4932. Gene: bub3. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

1.10Å R-factor: 0.152 R-free: 0.186

Authors:

D.K.Wilson,D.Cerna,E.Chew

Key ref:

D.K.Wilson et al. (2005). The 1.1-angstrom structure of the spindle checkpoint protein Bub3p reveals functional regions. J Biol Chem, 280, 13944-13951. PubMed id: 15644329 DOI: 10.1074/jbc.M412919200

Date:

03-Jan-05 Release date: 11-Jan-05

Protein chain

P26449  (BUB3_YEAST) -  Cell cycle arrest protein BUB3 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 341 a.a.

Struc: 342 a.a.

DOI no: 10.1074/jbc.M412919200

J Biol Chem 280:13944-13951 (2005)

PubMed id: 15644329

The 1.1-angstrom structure of the spindle checkpoint protein Bub3p reveals functional regions.

D.K.Wilson, D.Cerna, E.Chew.

ABSTRACT

Bub3p is a protein that mediates the spindle checkpoint, a signaling pathway that ensures correct chromosome segregation in organisms ranging from yeast to mammals. It is known to function by co-localizing at least two other proteins, Mad3p and the protein kinase Bub1p, to the kinetochore of chromosomes that are not properly attached to mitotic spindles, ultimately resulting in cell cycle arrest. Prior sequence analysis suggested that Bub3p was composed of three or four WD repeats (also known as WD40 and beta-transducin repeats), short sequence motifs appearing in clusters of 4-16 found in many hundreds of eukaryotic proteins that fold into four-stranded blade-like sheets. We have determined the crystal structure of Bub3p from Saccharomyces cerevisiae at 1.1 angstrom and a crystallographic R-factor of 15.3%, revealing seven authentic repeats. In light of this, it appears that many of these repeats therefore remain hidden in sequences of other proteins. Analysis of random and site-directed mutants identifies the surface of Bub3p involved in checkpoint function through binding of Bub1p and Mad3p. Sequence alignments indicate that these surfaces are mostly conserved across Bub3 proteins from diverse species. A structural comparison with other proteins containing WD repeats suggests that these folds may bind partner proteins using similar surface areas on the top and sides of the propeller. The sequences composing these regions are the most divergent within the repeat across all WD repeat proteins and could potentially be modulated to provide specificity in partner protein binding without perturbation of the core structure.

Selected figure(s)

Figure 4.
FIG. 4. Conservation of protein binding surfaces in known structures of WD repeat proteins complexed with partner proteins. Functional surfaces of the WD repeat proteins G and p40 indicate regions involved in partner protein binding and are similar to the Bub3p surface shown in Fig. 2, A and B. All models have an orientation similar to Fig. 1. Interaction surfaces: A, G binding to G (35); B, phosducin binding to G (33); C, p16 binding to p40 (27); D, p20 binding to p40 (27) are shown in red. These figures were prepared using the program GRASP (45).

Figure 6.
FIG. 6. Sequence alignments of Bub3 from various species. scBUB3, S. cerevisiae; hsBUB3, human; mmBUB3, mouse; xlBUB3, X. laevis; dmBUB3, Drosophila. Secondary structural elements are identified based on the yeast structure. Residues that are conserved among Bub3 homologs and shown in Fig. 2, B and C are shaded gray. Locations of mutants failing to rescue the BUB3-null mutant in this study are indicated by arrows.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2005, 280, 13944-13951) copyright 2005.

Figures were selected by an automated process.