3b6a | pdb_00003b6a
Crystal structure of the Streptomyces coelicolor TetR family protein ActR in complex with actinorhodin
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| 3b6a, resolution 3.05Å | |||||||||||||
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| Sites: | AC1, AC2, AC3, AC4, AC5, AC6, AC7 and AC8 | ||||||||||||
| Ligands: | ZCT | ||||||||||||
| Gene: | actR (Streptomyces coelicolor) | ||||||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||||||
Overview
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)-aceti c 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.
About this Structure
3B6A is a Single protein structure of sequence from Streptomyces coelicolor. Full crystallographic information is available from OCA.
Reference
Crystal structures of the Streptomyces coelicolor TetR-like protein ActR alone and in complex with actinorhodin or the actinorhodin biosynthetic precursor (S)-DNPA., Willems AR, Tahlan K, Taguchi T, Zhang K, Lee ZZ, Ichinose K, Junop MS, Nodwell JR, J Mol Biol. 2008 Mar 7;376(5):1377-87. Epub 2008 Jan 4. PMID:18207163
Page seeded by OCA on Thu Mar 20 18:56:25 2008
