Abstract
The pentapeptide-repeat protein EfsQnr from Enterococcus faecalis protects DNA gyrase from inhibition by fluoroquinolones. EfsQnr was cloned and purified to homogeneity, but failed to produce diffraction-quality crystals in initial crystallization screens. Treatment of EfsQnr with glutaraldehyde and the strong reducing agent borane-dimethylamine resulted in a derivatized protein which produced crystals that diffracted to 1.6 Å resolution; their structure was subsequently determined by single-wavelength anomalous dispersion. Analysis of the derivatized protein using Fourier transform ion cyclotron resonance mass spectrometry indicated a mass increase of 68 Da per free amino group. Electron-density maps about a limited number of structurally ordered lysines indicated that the modification was a cyclic pentylation of free amines, producing piperidine groups.
Original language | English (US) |
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Pages (from-to) | 462-469 |
Number of pages | 8 |
Journal | Acta Crystallographica Section D: Biological Crystallography |
Volume | 65 |
Issue number | 5 |
DOIs | |
State | Published - Apr 18 2009 |
Keywords
- Chemical modification
- Glutaraldehyde
- Pentapeptide-repeat proteins
- Reductive cyclic pentylation
ASJC Scopus subject areas
- Structural Biology