Crystal Structure of Apo ActR from Streptomyces coelicolor.

Experimental Data Snapshot

  • Resolution: 2.05 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.195 
  • R-Value Observed: 0.198 

wwPDB Validation   3D Report Full Report

This is version 1.2 of the entry. See complete history


Crystal structures of the Streptomyces coelicolor TetR-like protein ActR alone and in complex with actinorhodin or the actinorhodin biosynthetic precursor (S)-DNPA.

Willems, A.R.Tahlan, K.Taguchi, T.Zhang, K.Lee, Z.Z.Ichinose, K.Junop, M.S.Nodwell, J.R.

(2008) J Mol Biol 376: 1377-1387

  • DOI: https://doi.org/10.1016/j.jmb.2007.12.061
  • Primary Citation of Related Structures:  
    2OPT, 3B6A, 3B6C

  • PubMed Abstract: 

    Actinorhodin, an antibiotic produced by Streptomyces coelicolor, is exported from the cell by the ActA efflux pump. actA is divergently transcribed from actR, which encodes a TetR-like transcriptional repressor. We showed previously that ActR represses transcription by binding to an operator from the actA/actR intergenic region. Importantly, actinorhodin itself or various actinorhodin biosynthetic intermediates can cause ActR to dissociate from its operator, leading to derepression. This suggests that ActR may mediate timely self-resistance to an endogenously produced antibiotic by responding to one of its biosynthetic precursors. Here, we report the structural basis for this precursor-mediated derepression with crystal structures of homodimeric ActR by itself and in complex with either actinorhodin or the actinorhodin biosynthetic intermediate (S)-DNPA [4-dihydro-9-hydroxy-1-methyl-10-oxo-3-H-naphtho-[2,3-c]-pyran-3-(S)-acetic acid]. The ligand-binding tunnel in each ActR monomer has a striking hydrophilic/hydrophobic/hydrophilic arrangement of surface residues that accommodate either one hexacyclic actinorhodin molecule or two back-to-back tricyclic (S)-DNPA molecules. Moreover, our work also reveals the strongest structural evidence to date that TetR-mediated antibiotic resistance may have been acquired from an antibiotic-producer organism.

  • Organizational Affiliation

    Department of Biochemistry and Biomedical Sciences, McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ActII protein
A, B
234Streptomyces coelicolorMutation(s): 0 
Gene Names: actII
Find proteins for Q53901 (Streptomyces coelicolor)
Explore Q53901 
Go to UniProtKB:  Q53901
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ53901
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.05 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.195 
  • R-Value Observed: 0.198 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 55.648α = 90
b = 79.957β = 90
c = 104.027γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-02-05
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.2: 2023-12-27
    Changes: Data collection, Database references