2Y2Z

ligand-free form of TetR-like repressor SimR

Summary for 2Y2Z

• Entry DOI: 10.2210/pdb2y2z/pdb
• Related: 2Y30 2Y31
• Descriptor: PUTATIVE REPRESSOR SIMREG2 (2 entities in total)
• Functional Keywords: transcription, simocyclinone regulator, tetr-family
• Biological source: STREPTOMYCES ANTIBIOTICUS
• Total number of polymer chains: 1
• Total formula weight: 30240.22

Authors

Le, T.B.K.,Stevenson, C.E.M.,Fiedler, H.-P.,Maxwell, A.,Lawson, D.M.,Buttner, M.J. (deposition date: 2010-12-17, release date: 2011-03-09, Last modification date: 2024-05-08)

Primary citation

Le, T.B.K.,Stevenson, C.E.M.,Fiedler, H.-P.,Maxwell, A.,Lawson, D.M.,Buttner, M.J.
Structures of the Tetr-Like Simocyclinone Efflux Pump Repressor, Simr, and the Mechanism of Ligand-Mediated Derepression.
J.Mol.Biol., 408:40-, 2011

PubMed Abstract: Simocyclinone D8 (SD8), a potent DNA gyrase inhibitor made by Streptomyces antibioticus, is exported from the producing organism by the SimX efflux pump. The expression of simX is under the control of SimR, a member of the TetR family of transcriptional regulators. SimR represses simX transcription by binding to operators in the intergenic region between simR and simX. Previously, we have shown that the mature antibiotic SD8 or its biosynthetic intermediate, simocyclinone C4, can dissociate SimR from its operators, leading to derepression of simX and export of SD8 from the cell. This provides a mechanism that couples the biosynthesis of the antibiotic to its export. Here, we report the crystal structures of SimR alone and in complex with either SD8 or simocyclinone C4. The ligand-binding pocket is unusual compared to those of other characterized TetR-family transcriptional regulators: the structures show an extensive ligand-binding pocket spanning both monomers in the functional dimeric unit, with the aminocoumarin moiety of SD8 buried in the protein core, while the angucyclic polyketide moiety is partially exposed to bulk solvent. Through comparisons of the structures, we postulate a derepression mechanism for SimR that invokes rigid-body motions of the subunits relative to one another, coupled with a putative locking mechanism to restrict further conformational change.

PubMed: 21354180
DOI: 10.1016/J.JMB.2011.02.035

Experimental method

X-RAY DIFFRACTION (1.95 Å)