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

Item Type:Article
Title:Stability and DNA-binding properties of the omega regulator protein from the broad-host range Streptococcus pyogenes plasmid pSM19035
Creators Name:Misselwitz, R. and de la Hoz, A.B. and Ayora, S. and Welfle, K. and Behlke, J. and Murayama, K. and Saenger, W. and Alonso, J.C. and Welfle, H.
Abstract:At the transcriptional level, the pSM19035-encoded {omega} 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 {omega} protein and a variant with a C-terminal hexa-histidine tag ({omega}-H6) were characterized. The {omega} protein is mainly {alpha}-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 {omega}-H6 protein has a modified conformation with lower {alpha}-helix content (29%), lower thermal stability, and strongly reduced affinity to PcopS-DNA.
Keywords:Circular Dichroism, Fluorescence, Plasmid Copy Number Control, Protein Stability, Protein-DNA Interaction, Thermal Unfolding, Transcriptional Repressor, Urea Unfolding
Source:FEBS Letters
ISSN:0014-5793
Publisher:Elsevier (The Netherlands)
Volume:505
Number:3
Page Range:436-440
Date:1 January 2001
PubMed:View item in PubMed

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