The role of Cra in regulating acetate excretion and osmotic tolerance in E. coli K-12 and E. coli B at high density growth.

Background: E. coli B (BL21), unlike E.coli K-12 (JM109) is insensitive to glucose concentration and, therefore, grows faster and produces less acetate than E.

Dimerization of the class A G protein-coupled neurotensin receptor NTS1 alters G protein interaction.

G protein-coupled receptors (GPCRs) have been found as monomers but also as dimers or higher-order oligomers in cells. The relevance of the monomeric or dimeric receptor state for G protein activation is currently under debate for class A rhodopsin-like GPCRs. Clarification of this issue requires the availability of well defined receptor preparations as monomers or dimers and an assessment of their ligand-binding and G protein-coupling properties.

Extracellular structure of polysialic acid explored by on cell solution NMR.

The capsular polysaccharide of the pathogens Neisseria meningitidis serogroup B and of Escherichia coli K1, alpha(2 --> 8) polysialic acid (PSA), is unusual, because when injected into adult humans, it generates little or no antibody. In contrast, people infected with these pathogens generate specific serum antibodies. A structural study on cells is used to address this anomaly by characterizing antigen structures in vivo.

Large-scale expression and purification of a G-protein-coupled receptor for structure determination -- an overview.

Structure determination of G-protein-coupled receptors and other applications, such as nuclear magnetic resonance studies, require milligram quantities of purified, functional receptor protein on a regular basis. We present an overview on expression and purification studies with a receptor for neurotensin. Functional expression in Escherichia coli and an automated two-column purification routine allow ongoing crystallization experiments and studies on receptor-bound ligands.

Automated large-scale purification of a G protein-coupled receptor for neurotensin.

Structure determination of integral membrane proteins requires milligram amounts of purified, functional protein on a regular basis. Here, we describe a protocol for the purification of a G protein-coupled neurotensin receptor fusion protein at the 3-mg or 10-mg level using immobilized metal affinity chromatography and a neurotensin column in a fully automated mode. Fermentation at a 200-l scale of Escherichia coli expressing functional receptors provides the material needed to feed into the purification routine.