Overproduction of a Dominant Mutant of the Conserved Era GTPase Inhibits Cell Division in Escherichia coli.

Cell growth and division are coordinated, ensuring homeostasis under any given growth condition, with division occurring as cell mass doubles. The signals and controlling circuit(s) between growth and division are not well understood; however, it is known in that the essential GTPase Era, which is growth rate regulated, coordinates the two functions and may be a checkpoint regulator of both. We have isolated a mutant of Era that separates its effect on growth and division.

Similar modes of polypeptide recognition by export chaperones in flagellar biosynthesis and type III secretion.

Assembly of the bacterial flagellum and type III secretion in pathogenic bacteria require cytosolic export chaperones that interact with mobile components to facilitate their secretion. Although their amino acid sequences are not conserved, the structures of several type III secretion chaperones revealed striking similarities between their folds and modes of substrate recognition. Here, we report the first crystallographic structure of a flagellar export chaperone, Aquifex aeolicus FliS.

Structural basis for the substrate specificity of tobacco etch virus protease.

Because of its stringent sequence specificity, the 3C-type protease from tobacco etch virus (TEV) is frequently used to remove affinity tags from recombinant proteins. It is unclear, however, exactly how TEV protease recognizes its substrates with such high selectivity. The crystal structures of two TEV protease mutants, inactive C151A and autolysis-resistant S219D, have now been solved at 2.

The global regulator RNase III modulates translation repression by the transcription elongation factor N.

Efficient expression of most bacteriophage lambda early genes depends upon the formation of an antiterminating transcription complex to overcome transcription terminators in the early operons, p(L) and p(R). Formation of this complex requires the phage-encoded protein N, the first gene product expressed from the p(L) operon. The N leader RNA contains, in this order: the NUTL site, an RNase III-sensitive hairpin and the N ribosome-binding site.