Stability and DNA‐binding properties of the ω regulator protein from the broad‐host rangeStreptococcus pyogenesplasmid pSM19035
Open Access
- 21 September 2001
- journal article
- Published by Wiley in FEBS Letters
- Vol. 505 (3) , 436-440
- https://doi.org/10.1016/s0014-5793(01)02865-4
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 bindsPcopS‐DNA with high affinity. The ω‐H6protein has a modified conformation with lower α‐helix content (29%), lower thermal stability, and strongly reduced affinity toPcopS‐DNA.Keywords
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