Open AccessOligomeric structure of the repressor of the bacteriophage Mu early operon
Author(s) -
Alazard Robert,
Ebel Christine,
VenienBryan Catherine,
Mourey Lionel,
Samama Jean Pierre,
Chandler Michael
Publication year - 1998
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1998.2520408.x
Subject(s) - random hexamer , repressor , protein quaternary structure , operon , bacteriophage , chemistry , lytic cycle , lysogenic cycle , gal operon , operator (biology) , biology , crystallography , stereochemistry , biochemistry , genetics , protein subunit , escherichia coli , gene , gene expression , virus
The regulation of the lytic and lysogenic development in the life cycle of bacteriophage Mu is regulated in part by its repressor, c, which binds to three operator sites, O1, O2 and O3, overlapping two divergent promoters. The oligomeric structure of this repressor protein was investigated by hydrodynamic and biochemical methods. Size‐exclusion chromatography, analytical ultracentrifugation, dynamic light scattering, crosslinking and direct electron microscopy observations suggest that c exists primarily as a hexamer with a molecular mass of 120−140 kDa at low concentrations, i.e. in the 10‐μM range. This molecule undergoes a self‐assembly process leading to dodecamers and higher order species as the concentration is further increased in a manner depending on the nature of the solvent. Our results also suggest that these species have an elongated structure, and a possible arrangement of the subunits within the hexamer is proposed. The implication of this unusual quaternary structure for a repressor in its interaction with the operator sites O1 and O2 remains to be elucidated.