Open AccessModerately thermostable phage Φ11 Cro repressor has novel DNA-binding capacity and physicochemical properties
Author(s) -
Malabika Das,
Tridib Ganguly,
Amitava Bandhu,
Rajkrishna Mondal,
Palas K. Chanda,
Biswanath Jana,
Subrata Sau
Publication year - 2009
Publication title -
bmb reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.511
H-Index - 77
eISSN - 1976-670X
pISSN - 1976-6696
DOI - 10.5483/bmbrep.2009.42.3.160
Subject(s) - repressor , gene , dna , lambda phage , chemistry , microbiology and biotechnology , biology , crystallography , genetics , bacteriophage , escherichia coli , gene expression
The temperate Staphylococcus aureus phage Phi11 harbors cI and cro repressor genes similar to those of lambdoid phages. Using extremely pure Phi11 Cro (the product of the Phi11 cro gene) we demonstrated that this protein possesses a single domain structure, forms dimers in solution at micromolar concentrations and maintains a largely alpha-helical structure even at 45 degrees C. Phi11 Cro was sensitive to thermolysin at temperatures ranging from 55-75 degrees C and began to aggregate at ~63 degrees C, suggesting that the protein is moderately thermostable. Of the three homologous 15-bp operators (O1, O2, and O3) in the Phi11 cI-cro intergenic region, Phi11 Cro only binds efficiently to O3, which is located upstream of the cI gene. Our comparative analyses indicate that the DNA binding capacity, secondary structure and dimerization efficiency of thermostable Phi11 Cro are distinct from those of P22 Cro and lambda Cro, the best characterized representatives of the two structurally different Cro families.