PDBsum entry 1sw6

Transcription regulation

PDB id: 1sw6

Contents

Protein chains

254 a.a. *

Waters ×215

* Residue conservation analysis

PDB id:

1sw6

Name:

Transcription regulation

Title:

S. Cerevisiae swi6 ankyrin-repeat fragment

Structure:

Regulatory protein swi6. Chain: a, b. Fragment: ankyrin-repeat domain. Engineered: yes

Source:

Saccharomyces cerevisiae. Baker's yeast. Organism_taxid: 4932. Gene: swi6. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

2.10Å R-factor: 0.222 R-free: 0.251

Authors:

R.Foord,I.A.Taylor,S.G.Sedgwick,S.J.Smerdon

Key ref:

R.Foord et al. (1999). X-ray structural analysis of the yeast cell cycle regulator Swi6 reveals variations of the ankyrin fold and has implications for Swi6 function. Nat Struct Biol, 6, 157-165. PubMed id: 10048928 DOI: 10.1038/5845

Date:

28-Sep-98 Release date: 15-Sep-99

Protein chains

P09959  (SWI6_YEAST) -  Regulatory protein SWI6 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 803 a.a.

Struc: 254 a.a.

DOI no: 10.1038/5845

Nat Struct Biol 6:157-165 (1999)

PubMed id: 10048928

X-ray structural analysis of the yeast cell cycle regulator Swi6 reveals variations of the ankyrin fold and has implications for Swi6 function.

R.Foord, I.A.Taylor, S.G.Sedgwick, S.J.Smerdon.

ABSTRACT

Swi6 is a 92,000 Mr protein common to two distinct transcriptional activation complexes (SBF and MBF) that coordinate gene expression at the G1-S boundary of the yeast cell cycle. The X-ray structure of a central 36,000 Mr fragment has been determined and refined at 2.1 A resolution. The structure reveals a basic framework of five ankyrin repeat modules that is elaborated through a series of helical insertions distinguishing it from structures of other ankyrin repeat proteins. A second domain contains an approximately 30-residue region of extended structure that interacts with the ankyrin repeat core over a substantial proportion of its surface. Conservation of residues buried by these interactions indicates that all members of the Swi6/Cdc10 family share a similar architecture. Several temperature-sensitive mutations within Swi6 and Cdc10 appear to disrupt these interdomain contacts rather than destabilize the ankyrin repeat core. The unusual domain arrangement may be crucial for the modulation of interactions with other co-regulatory molecules such as cyclin-CDK complexes, and has implications for the quaternary interactions within the multisubunit SBF and MBF transcription complexes.

Selected figure(s)

Figure 1.
Figure 1. a, Schematic representation of the protein components and DNA−binding specificity of the SBF and MBF complexes. b, Regions of sequence homology within the Swi6/Cdc10 family. The leucine heptad repeat, present only in Swi6 and Cdc10, is indicated, together with the boundaries of the Swi6 fragment (Swi6−36kD) used in this study.

Figure 5.
Figure 5. a, Contacts between the AAD and the upper surface of the ANK core. The AAD is shown as a coil with side chains attached. The molecular surface of the ANK is colored white, and the surface associated with atoms within van der Waals contact of the AAD is colored red. b, Residues within the first ANK repeat of Swi6 (left) generate an extensive hydrophobic surface (red) that is partially occluded through interactions with the AAD (shown as blue coil). Mapping sequence substitutions in Swi4 (right) and Mbp1 (not shown) onto the Swi6 backbone structure shows that this surface is conserved and suggests that a similar AAD−like structure is likely to be present in these and the other Swi6−related proteins. The surface associated with the conserved Swi6 Trp 344 is colored blue. Parts (a) and (b) produced using GRASP^61. c, Homology within the region immediately N−terminal to the ANK core of Swi6/Cdc10−related proteins. The homologous cluster of nonpolar residues and the N−terminal segment of the first ANK repeat are boxed. Figs 4 and 5c produced using ALSCRIPT^62.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (1999, 6, 157-165) copyright 1999.

Figures were selected by an automated process.