3MQ0: Crystal Structure Of Agobacterium Tumefaciens Repressor Blcr

The Agrobacterium tumefaciens BlcR is a member of the emerging isocitrate lyase transcription regulators that negatively regulates metabolism of gamma-butyrolactone, and its repressing function is relieved by succinate semialdehyde (SSA). Our crystal structure showed that BlcR folded into the DNA- and SSA-binding domains and dimerized via the DNA-binding domains. Mutational analysis identified residues, including Phe(147), that are important for SSA association; BlcR(F147A) existed as tetramer. Two BlcR dimers bound to target DNA and in a cooperative manner, and the distance between the two BlcR-binding sequences in DNA was critical for BlcR-DNA association. Tetrameric BlcR(F147A) retained DNA binding activity, and importantly, this activity was not affected by the distance separating the BlcR-binding sequences in DNA. SSA did not dissociate tetrameric BlcR(F147A) or BlcR(F147A)-DNA. As well as in the SSA-binding site, Phe(147) is located in a structurally flexible loop that may be involved in BlcR oligomerization. We propose that SSA regulates BlcR DNA-binding function via oligomerization.
PDB ID: 3MQ0Download
MMDB ID: 89517
PDB Deposition Date: 2010/4/27
Updated in MMDB: 2012/09
Experimental Method:
x-ray diffraction
Resolution: 1.79  Å
Source Organism:
Similar Structures:
Biological Unit for 3MQ0: dimeric; determined by author and by software (PISA)
Molecular Components in 3MQ0
Label Count Molecule
Proteins (2 molecules)
Transcriptional Repressor of the Blcabc Operon
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB