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Determination of the Optimal Chromosomal Location(s) for a DNA Element in Escherichia coli Using a Novel Transposon-mediated Approach
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Domain architecture of a high mobility group A-type bacterial transcriptional factor

S Padmanabhan1, M Elías-Arnanz, E Carpio

  • 1Departamento de Genética y Microbiologia and Area de Inmunologia, Universidad de Murcia, 30071 Murcia, Spain. padhu@um.es

The Journal of Biological Chemistry
|September 5, 2001
PubMed

Insights

Myxococcus xanthus CarD protein, similar to eukaryotic HMGA proteins, binds AT-rich DNA. Phosphorylation reduces its DNA binding, impacting transcriptional regulation.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Myxococcus xanthus CarD is a transcriptional factor involved in key developmental processes.
  • CarD is unique in prokaryotes for possessing AT-hook and acidic regions, similar to eukaryotic HMGA proteins.
  • Eukaryotic HMGA proteins are architectural factors influencing DNA and chromatin structure.

Purpose of the Study:

  • To investigate the structural and functional characteristics of Myxococcus xanthus CarD.
  • To compare the DNA-binding properties of CarD with eukaryotic HMGA proteins.
  • To explore the role of post-translational modification (phosphorylation) on CarD function.

Main Methods:

  • Structural analysis of CarD domains (N-terminal and C-terminal).
  • DNA-binding assays to assess CarD's affinity for AT-rich sequences.
  • In vitro phosphorylation studies using casein kinase II.

Main Results:

  • CarD exists predominantly as a dimer with two distinct domains: a structured N-terminal domain and an unstructured C-terminal domain containing AT-hook and acidic regions.
  • CarD specifically binds to the minor groove of AT-rich DNA, similar to HMGA proteins.
  • Phosphorylation of the acidic region by casein kinase II significantly reduces CarD's DNA binding affinity.
  • The acidic region contributes to both DNA binding modulation and structural stability.

Conclusions:

  • CarD exhibits structural and functional similarities to eukaryotic HMGA proteins, suggesting conserved DNA-binding mechanisms.
  • The plasticity of CarD's domain organization likely contributes to its role as a general transcriptional factor in Myxococcus xanthus.
  • Regulation of CarD DNA binding via phosphorylation offers a mechanism for controlling gene expression during development.

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