PDBsum entry 4bl0

Cell cycle

PDB id: 4bl0

Contents

Protein chains

331 a.a.

44 a.a.

12 a.a.

45 a.a.

12 a.a.

Metals

_MG ×2

Waters ×356

PDB id:

4bl0

Name:

Cell cycle

Title:

Crystal structure of yeast bub3-bub1 bound to phospho-spc105

Structure:

Cell cycle arrest protein bub3. Chain: a, d. Engineered: yes. Checkpoint serine/threonine-protein kinase bub1. Chain: b, e. Fragment: extended bub3-binding motif (a.K.A glebs motif), residues 289-359. Engineered: yes. Spindle pole body component spc105.

Source:

Saccharomyces cerevisiae. Baker's yeast. Organism_taxid: 4932. Expressed in: escherichia coli. Expression_system_taxid: 511693. Expression_system_variant: plyss. Synthetic: yes. Organism_taxid: 4932

Resolution:

1.95Å R-factor: 0.180 R-free: 0.192

Authors:

I.Primorac,J.R.Weir,A.Musacchio

Key ref:

I.Primorac et al. (2013). Bub3 reads phosphorylated MELT repeats to promote spindle assembly checkpoint signaling. Elife, 2, e01030. PubMed id: 24066227 DOI: 10.7554/eLife.01030

Date:

30-Apr-13 Release date: 18-Sep-13

Protein chains

P26449  (BUB3_YEAST) -  Spindle assembly checkpoint protein BUB3 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 341 a.a.

Struc: 331 a.a.

Protein chain

P41695  (BUB1_YEAST) -  Spindle assembly checkpoint serine/threonine-protein kinase BUB1 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 1021 a.a.

Struc: 44 a.a.

Protein chain

P53148  (SP105_YEAST) -  Outer kinetochore KNL1 complex subunit SPC105 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 917 a.a.

Struc: 12 a.a.*

Protein chain

P41695  (BUB1_YEAST) -  Spindle assembly checkpoint serine/threonine-protein kinase BUB1 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 1021 a.a.

Struc: 45 a.a.

Protein chain

P53148  (SP105_YEAST) -  Outer kinetochore KNL1 complex subunit SPC105 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 917 a.a.

Struc: 12 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains B, E: E.C.2.7.11.1 - non-specific serine/threonine protein kinase.
• Reaction:
  1. L-seryl-[protein] + ATP = O-phospho-L-seryl-[protein] + ADP + H⁺
  2. L-threonyl-[protein] + ATP = O-phospho-L-threonyl-[protein] + ADP + H⁺

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.7554/eLife.01030

Elife 2:e01030 (2013)

PubMed id: 24066227

Bub3 reads phosphorylated MELT repeats to promote spindle assembly checkpoint signaling.

I.Primorac, J.R.Weir, E.Chiroli, F.Gross, I.Hoffmann, S.van Gerwen, A.Ciliberto, A.Musacchio.

ABSTRACT

Regulation of macromolecular interactions by phosphorylation is crucial in signaling networks. In the spindle assembly checkpoint (SAC), which enables errorless chromosome segregation, phosphorylation promotes recruitment of SAC proteins to tensionless kinetochores. The SAC kinase Mps1 phosphorylates multiple Met-Glu-Leu-Thr (MELT) motifs on the kinetochore subunit Spc105/Knl1. The phosphorylated MELT motifs (MELT(P)) then promote recruitment of downstream signaling components. How MELT(P) motifs are recognized is unclear. In this study, we report that Bub3, a 7-bladed β-propeller, is the MELT(P) reader. It contains an exceptionally well-conserved interface that docks the MELT(P) sequence on the side of the β-propeller in a previously unknown binding mode. Mutations targeting the Bub3 interface prevent kinetochore recruitment of the SAC kinase Bub1. Crucially, they also cause a checkpoint defect, showing that recognition of phosphorylated targets by Bub3 is required for checkpoint signaling. Our data provide the first detailed mechanistic insight into how phosphorylation promotes recruitment of checkpoint proteins to kinetochores. DOI:http://dx.doi.org/10.7554/eLife.01030.001.