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Abstract:
Cyclic di-GMP (c-di-GMP) is a second messenger that modulates multiple
responses to environmental and cellular signals in bacteria. Here we
identify CdbA, a DNA-binding protein of the ribbon-helix-helix family
that binds c-di-GMP in Myxococcus xanthus. CdbA is essential for
viability, and its depletion causes defects in chromosome organization
and segregation leading to a block in cell division. The protein binds
to the M. xanthus genome at multiple sites, with moderate sequence
specificity; however, its depletion causes only modest changes in
transcription. The interactions of CdbA with c-di-GMP and DNA appear to
be mutually exclusive and residue substitutions in CdbA regions
important for c-di-GMP binding abolish binding to both c-di-GMP and DNA,
rendering these protein variants non-functional in vivo. We propose that
CdbA acts as a nucleoid-associated protein that contributes to
chromosome organization and is modulated by c-di-GMP, thus revealing a
link between c-di-GMP signaling and chromosome biology. The second
messenger c-di-GMP modulates multiple responses to environmental and
cellular signals in bacteria. Here, Skotnicka et al. identify a protein
that binds c-di-GMP and contributes to chromosome organization and
segregation in Myxococcus xanthus, with DNA-binding activity regulated
by c-di-GMP.
