title: Stability and DNA-binding properties of the omega regulator protein from the broad-host range Streptococcus pyogenes plasmid pSM19035.
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-H(6)) were characterized. The omega protein is mainly alpha-helical (42%), occurs as homodimer in solution, unfolds thermally with half transition temperatures, T(m), between approximately 43 and approximately 78 degrees C depending on the ionic strength of the buffer, and binds PcopS-DNA with high affinity. The omega-H(6) protein has a modified conformation with lower alpha-helix content (29%), lower thermal stability, and strongly reduced affinity to PcopS-DNA.
authors.affiliation: Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Misselwitz
authors.forename: A B
authors.initials: AB
authors.lastname: de la Hoz
authors.forename: S
authors.initials: S
authors.lastname: Ayora
authors.forename: K
authors.initials: K
authors.lastname: Welfle
authors.forename: J
authors.initials: J
authors.lastname: Behlke
authors.forename: K
authors.initials: K
authors.lastname: Murayama
authors.forename: W
authors.initials: W
authors.lastname: Saenger
authors.forename: J C
authors.initials: JC
authors.lastname: Alonso
authors.forename: H
authors.initials: H
authors.lastname: Welfle
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002942:Circular Dichroism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019281:Dimerization; D010957:Plasmids; D011489:Protein Denaturation; D013050:Spectrometry, Fluorescence; D013297:Streptococcus pyogenes / Q000235:genetics*; D013816:Thermodynamics; D014461:Ultracentrifugation
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins