PDBsum entry: 1b0n

Transcription regulator

PDB id: 1b0n

Contents

Protein chains

103 a.a. *

31 a.a. *

Metals

_ZN ×5

Waters ×117

* Residue conservation analysis

PDB id:

1b0n

Name:

Transcription regulator

Title:

Sinr protein/sini protein complex

Structure:

Protein (sinr protein). Chain: a. Engineered: yes. Protein (sini protein). Chain: b. Engineered: yes

Source:

Bacillus subtilis. Organism_taxid: 1423. Cellular_location: cytoplasm. Gene: sinr, sini. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Tetramer (from PQS)

Resolution:

1.90Å R-factor: 0.199 R-free: 0.245

Authors:

R.J.Lewis,J.A.Brannigan,W.A.Offen,I.Smith,A.J.Wilkinson

Key ref:

R.J.Lewis et al. (1998). An evolutionary link between sporulation and prophage induction in the structure of a repressor:anti-repressor complex. J Mol Biol, 283, 907-912. PubMed id: 9799632 DOI: 10.1006/jmbi.1998.2163

Date:

11-Nov-98 Release date: 13-Jan-99

Protein chain

P06533  (SINR_BACSU) -  HTH-type transcriptional regulator sinR

Seq: 111 a.a.

Struc: 103 a.a.

Protein chain

P23308  (SINI_BACSU) -  Protein sinI

Seq: 57 a.a.

Struc: 31 a.a.

 Gene Ontology (GO) functional annotation 

• Biological process: sporulation resulting in formation of a cellular spore (3 terms)
• Biochemical function: DNA binding (3 terms)

DOI no: 10.1006/jmbi.1998.2163

J Mol Biol 283:907-912 (1998)

PubMed id: 9799632

An evolutionary link between sporulation and prophage induction in the structure of a repressor:anti-repressor complex.

R.J.Lewis, J.A.Brannigan, W.A.Offen, I.Smith, A.J.Wilkinson.

ABSTRACT

Spore formation is an extreme response of some bacteria to adversity. In Bacillus subtilis the proteins of the sin, sporulation inhibition, region form a component of an elaborate molecular circuitry that regulates the commitment to sporulation. SinR is a tetrameric repressor protein that binds to the promoters of genes essential for entry into sporulation and prevents their transcription. This repression is overcome through the activity of SinI, which disrupts the SinR tetramer through the formation of a SinI-SinR heterodimer. The interactions governing this curious quaternary transition are revealed in the crystal structure of the SinI-SinR complex. The most striking, and unexpected, finding is that the tertiary structure of the DNA-binding domain of SinR is identical with that of the corresponding domains of the repressor proteins, CI and Cro, of bacteriophage 434 that regulate lysis/lysogeny. This structural similarity greatly exceeds that between SinR and any bacterial protein or between the 434 repressor proteins and their homologues in the closely related bacteriophage lambda. The close evolutionary relationship implied by the structures of SinR and the 434 repressors provokes both comparison of their functions and a speculative consideration of the intriguing possibility of an evolutionary link between the two adaptive responses, sporulation and prophage induction.

Selected figure(s)

Figure 2.
Figure 2. Top, The multimerisation domain of SinI-SinR with SinI in blue and SinR in red. The side-chains of residues that contribute to the hydrophobic core are drawn in ball-and-stick. Middle, Overlay of residues 13-39 of SinI onto residues 76-102 of SinR by least-squares minimisation of differences in main-chain atomic positions. Bottom, Sequence alignment of residues 65-103 of SinR with residues 2-40 of SinI. The residues forming the hydrophobic core align exactly and are denoted by asterisks (*).

Figure 4.
Figure 4. A representation of the steps involved in sporulation in B. subtilis (left) and prophage induction in a lysogenic bacterium (right).

The above figures are reprinted by permission from Elsevier: J Mol Biol (1998, 283, 907-912) copyright 1998.

Figures were selected by an automated process.