Crystal structure of Mycobacterium tuberculosis CRP-FNR family transcription factor Cmr (Rv1675c)

Experimental Data Snapshot

  • Resolution: 1.85 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.174 
  • R-Value Observed: 0.176 

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Novel structural features drive DNA binding properties of Cmr, a CRP family protein in TB complex mycobacteria.

Ranganathan, S.Cheung, J.Cassidy, M.Ginter, C.Pata, J.D.McDonough, K.A.

(2018) Nucleic Acids Res 46: 403-420

  • DOI: https://doi.org/10.1093/nar/gkx1148
  • Primary Citation of Related Structures:  
    5W5A, 5W5B

  • PubMed Abstract: 

    Mycobacterium tuberculosis (Mtb) encodes two CRP/FNR family transcription factors (TF) that contribute to virulence, Cmr (Rv1675c) and CRPMt (Rv3676). Prior studies identified distinct chromosomal binding profiles for each TF despite their recognizing overlapping DNA motifs. The present study shows that Cmr binding specificity is determined by discriminator nucleotides at motif positions 4 and 13. X-ray crystallography and targeted mutational analyses identified an arginine-rich loop that expands Cmr's DNA interactions beyond the classical helix-turn-helix contacts common to all CRP/FNR family members and facilitates binding to imperfect DNA sequences. Cmr binding to DNA results in a pronounced asymmetric bending of the DNA and its high level of cooperativity is consistent with DNA-facilitated dimerization. A unique N-terminal extension inserts between the DNA binding and dimerization domains, partially occluding the site where the canonical cAMP binding pocket is found. However, an unstructured region of this N-terminus may help modulate Cmr activity in response to cellular signals. Cmr's multiple levels of DNA interaction likely enhance its ability to integrate diverse gene regulatory signals, while its novel structural features establish Cmr as an atypical CRP/FNR family member.

  • Organizational Affiliation

    Department of Biomedical Sciences, School of Public Health, University at Albany, SUNY, Albany, NY 12201, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
HTH-type transcriptional regulator Cmr
A, B
247Mycobacterium tuberculosis H37RvMutation(s): 0 
Gene Names: cmrMT1714
Find proteins for P9WMH5 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv))
Explore P9WMH5 
Go to UniProtKB:  P9WMH5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP9WMH5
Sequence Annotations
  • Reference Sequence
Small Molecules
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on MSE
A, B
Experimental Data & Validation

Experimental Data

  • Resolution: 1.85 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.174 
  • R-Value Observed: 0.176 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 51.615α = 90
b = 92.244β = 90
c = 102.758γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
HKL-2000data scaling
PDB_EXTRACTdata extraction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2017-12-13
    Type: Initial release
  • Version 1.1: 2018-01-24
    Changes: Database references
  • Version 1.2: 2019-01-09
    Changes: Data collection, Source and taxonomy