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

FEBS Letters

Welfle, Karin¹  Behlke, Joachim¹  Murayama, Kazutaka²  de la Hoz, Ana B.³  Misselwitz, Rolf¹  Welfle, Heinz¹  Ayora, Silvia³  Saenger, Wolfram²  Alonso, Juan C.³ 

[1] Max-Delbrück-Centrum für Molekulare Medizin, D-13092 Berlin, Germany;Institut für Kristallographie, Freie Universität Berlin, D-14195 Berlin, Germany;Departamento de Biotecnologı́a Microbiana, Centro Nacional de Biotecnologı́a, C.S.I.C., E-28049 Madrid, Spain

关键词: Plasmid copy number control;    Transcriptional repressor;    Protein–DNA interaction;    Protein stability;    Circular dichroism;    Fluorescence;    Thermal unfolding;    Urea unfolding;   

DOI  :  10.1016/S0014-5793(01)02865-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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, T _m, 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.

【 授权许可】

Unknown