Stability and DNA-binding properties of the ω regulator protein from the broad-host range Streptococcus pyogenes plasmid pSM19035

Rolf Misselwitz, Ana B. De La Hoz, Silvia Ayora, Karin Welfle, Joachim Behlke, Kazutaka Murayama, Wolfram Saenger, Juan C. Alonso, Heinz Welfle

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

At the transcriptional level, the pSM19035-encoded ω protein coordinates the expression of proteins required for control of copy number and maintenance of plasmids. Using circular dichroism, fluorescence spectroscopy, ultracentrifugation and an electrophoretic mobility shift assay, the wild-type ω protein and a variant with a C-terminal hexa-histidine tag (ω-H6) were characterized. The ω protein is mainly α-helical (42%), occurs as homodimer in solution, unfolds thermally with half transition temperatures, Tm, between ∼43 and ∼78°C depending on the ionic strength of the buffer, and binds PcopS-DNA with high affinity. The ω-H6 protein has a modified conformation with lower α-helix content (29%), lower thermal stability, and strongly reduced affinity to PcopS-DNA.

Original languageEnglish
Pages (from-to)436-440
Number of pages5
JournalFEBS Letters
Volume505
Issue number3
DOIs
Publication statusPublished - 2001 Sep 21
Externally publishedYes

Keywords

  • Circular dichroism
  • Fluorescence
  • Plasmid copy number control
  • Protein stability
  • Protein-DNA interaction
  • Thermal unfolding
  • Transcriptional repressor
  • Urea unfolding

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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