http://hdl.handle.net/2328/8262 2013-05-21T19:24:23Z http://hdl.handle.net/2328/25947 Title: The staphylococcal QacR multidrug regulator binds a correctly spaced operator as a pair of dimers Authors: Grkovic, Steve; Brown, Melissa Hackett; Schumacher, Maria A; Brennan, Richard G; Skurray, Ronald Anthony Abstract: Expression of the Staphylococcus aureusplasmid-encoded QacA multidrug transporter is regulated by the divergently encoded QacR repressor protein. To circumvent the formation of disulfide-bonded degradation products, site-directed mutagenesis to replace the two cysteine residues in wild-type QacR was undertaken. Analysis of a resultant cysteineless QacR derivative indicated that it retained full DNA-binding activities in vivo and in vitro and continued to be fully proficient for the mediation of induction ofqacA expression in response to a range of structurally dissimilar multidrug transporter substrates. The cysteineless QacR protein was used in cross-linking and dynamic light-scattering experiments to show that its native form was a dimer, whereas gel filtration indicated that four QacR molecules bound per DNA operator site. The addition of inducing compounds led to the dissociation of the four operator-bound QacR molecules from the DNA as dimers. Binding of QacR dimers to DNA was found to be dependent on the correct spacing of the operator half-sites. A revised model proposed for the regulation ofqacA expression by QacR features the unusual characteristic of one dimer of the regulatory protein binding to each operator half-site by a process that does not appear to require the prior self-assembly of QacR into tetramers. 2001-01-01T00:00:00Z http://hdl.handle.net/2328/10775 Title: A review of brain studies of possums and gliders Authors: Sanderson, Kenneth James 2004-01-01T00:00:00Z http://hdl.handle.net/2328/9900 Title: Codon-optimized Reading Frames Facilitate High-Level Expression of the HIV-1 Minor Proteins Authors: Anson, Donald; Dunning, K R 2005-01-01T00:00:00Z http://hdl.handle.net/2328/9899 Title: Magnetic and Fluorescence Encoded Polystyrene Microparticles for Cell Separation Authors: Voelcker, Nicolas Hans; Anglin, Emily Jessica; Thissen, Helmut Werner; MacArdle, Peter James; Fenech, Michael; Bailey, Sheree; Bradbury, Diana Mary 2008-01-01T00:00:00Z