RUB »Microbial Biology » Research

1. RNA thermometers

Structured RNA regions influence every step in the gene expression program. Many bacterial heat shock and virulence genes are regulated by RNA thermometers (RNATs), which are molecular zippers that control translation initiation. They adopt a structure that blocks the ribosome binding site at low temperatures. A temperature upshift to 37°C (virulence genes) or higher (heat shock genes) destabilizes the structure and permits translation.

 

2. Regulated proteolysis

(SFB642: GTP- and ATP dependent membrane processes)

The FtsH protease of E. coli controls important cellular processes like the heat shock response and lipopolysaccharide (LPS) biosynthesis by controlled proteolysis of the responsible key factors. Induction of the heat shock response requires the alternative sigma factor RpoH (Sigma32). Degradation of RpoH under non-stress conditions requires FtsH and the DnaKJ chaperone system. Little is known about proteolysis of LpxC, the key enzyme in LPS biosynthesis. We study how the FtsH protease recognizes its substrate and attempt to identify the turnover elements in RpoH and LpxC by genetic and biochemical approaches.

 

3. Bacterial membrane biosynthesis

Every living cell is enveloped by at least one membrane, which provides the first line of defense against toxic compounds and harmful conditions. We are interested in the biosynthesis of phosphatidylcholine (PC), an unusual phospholipid in bacteria that plays an important role in stress resistance and host-microbe interactions. We biochemically characterize the enzymes of three different PC biosynthesis pathways that operate either at the phospholipid head group or at the fatty acid site chains.

 

4. Metal-responsive gene regulation in bacteria

Metals are essential for the catalytic activity of very many enzymes, but are toxic in free form. Hence, bacteria tightly control expression of their metalloenzymes and metal-specific uptake systems.
Since long, our group is interested in molybdenum (Mo)-responsive gene regulation in the photosynthetic bacterium Rhodobacter capsulatus, which is capable of synthesizing a Mo-dependent and a Mo-free nitrogenase, which enable this strain to grow on expense of dinitrogen from air as the sole source of nitrogen. In particular, we are interested in the molecular mechanisms controlling these nitrogenases and a high-affinity Mo transporter.