New pleiotropic effects of eliminating a rare tRNA from Streptomyces coelicolor, revealed by combined proteomic and transcriptomic analysis of liquid cultures.

Background: In Streptomyces coelicolor, bldA encodes the only tRNA for a rare leucine codon, UUA. This tRNA is unnecessary for growth, but is required for some aspects of secondary metabolism and morphological development. We describe a transcriptomic and proteomic analysis of the effects of deleting bldA on cellular processes during submerged culture: conditions relevant to the industrial production of antibiotics.

A bacterial hormone (the SCB1) directly controls the expression of a pathway-specific regulatory gene in the cryptic type I polyketide biosynthetic gene cluster of Streptomyces coelicolor.

Gamma-butyrolactone signalling molecules are produced by many Streptomyces species, and several have been shown to regulate antibiotic production. In Streptomyces coelicolor A3(2) at least one gamma-butyrolactone (SCB1) has been shown to stimulate antibiotic production, and genes encoding proteins that are involved in its synthesis (scbA) and binding (scbR) have been characterized. Expression of these genes is autoregulated by a complex mechanism involving the gamma-butyrolactone.

Efficacy and mode of action of hammerhead and hairpin ribozymes against various HIV-1 target sites.

Ribozymes have been proposed as gene therapy agents against HIV-1, although many fundamental questions about their mechanism of action remain unclear. Few studies have compared directly the potential of different modified ribozyme species against a particular target. Here we compare the relative abilities of hammerhead (HhU5) and hairpin (HpU5) ribozymes directed against a well-studied target RNA that has therapeutic potential, located in the untranslated 5' region (U5), to inhibit HIV-1 replication.

Negative feedback regulation of dnaK, clpB and lon expression by the DnaK chaperone machine in Streptomyces coelicolor, identified by transcriptome and in vivo DnaK-depletion analysis.

The dnaK operon of Streptomyces coelicolor encodes the DnaK chaperone machine and the negative autoregulator HspR, which confers repression of the operon by binding to several inverted repeat sequences in the promoter region, dnaKp. Previous in vitro studies demonstrated that DnaK forms a specific complex with HspR bound to its operator sequences in dnaKp, and a model was proposed in which DnaK functions as a corepressor of the dnaK operon (Bucca, G., Brassington, A.