Structures of carbon catabolite protein A-(HPr-Ser46-P) bound to diverse catabolite response element sites reveal the basis for high-affinity binding to degenerate DNA operators.

In Gram-positive bacteria, carbon catabolite protein A (CcpA) is the master regulator of carbon catabolite control, which ensures optimal energy usage under diverse conditions. Unlike other LacI-GalR proteins, CcpA is activated for DNA binding by first forming a complex with the phosphoprotein HPr-Ser46-P. Bacillus subtilis CcpA functions as both a transcription repressor and activator and binds to more than 50 operators called catabolite response elements (cres).

Structure of the Trypanosoma brucei p22 protein, a cytochrome oxidase subunit II-specific RNA-editing accessory factor.

Kinetoplastid RNA (k-RNA) editing is a complex process in the mitochondria of kinetoplastid protozoa, including Trypanosoma brucei, that involves the guide RNA-directed insertion and deletion of uridines from precursor-mRNAs to produce mature, translatable mRNAs. k-RNA editing is performed by multiprotein complexes called editosomes. Additional non-editosome components termed k-RNA-editing accessory factors affect the extent of editing of specific RNAs or classes of RNAs.

CcpA mutants with differential activities in Bacillus subtilis.

CcpA is the master regulator for carbon catabolite regulation in Bacillus subtilis and regulates more than 300 genes by repression or activation. To revealthe effects of different functional domains of CcpA on various regulatory modes, we compared the activities of CcpA point mutants in activation (alsS, ackA) and repression (xynP, gntR). CcpA variants mutated at residues in the HPrSerP-binding region without allosteric functions are inactive.

Interference of components of the phosphoenolpyruvate phosphotransferase system with the central virulence gene regulator PrfA of Listeria monocytogenes.

Analysis of Listeria monocytogenes ptsH, hprK, and ccpA mutants defective in carbon catabolite repression (CCR) control revealed significant alterations in the expression of PrfA-dependent genes. The hprK mutant showed high up-regulation of PrfA-dependent virulence genes upon growth in glucose-containing medium whereas expression of these genes was even slightly down-regulated in the ccpA mutant compared to the wild-type strain. The ptsH mutant could only grow in a rich culture medium, and here the PrfA-dependent genes were up-regulated as in the hprK mutant.

Species-specific differences in the activity of PrfA, the key regulator of listerial virulence genes.

PrfA, the master regulator of LIPI-1, is indispensable for the pathogenesis of the human pathogen Listeria monocytogenes and the animal pathogen Listeria ivanovii. PrfA is also present in the apathogenic species Listeria seeligeri, and in this study, we elucidate the differences between PrfA proteins from the pathogenic and apathogenic species of the genus Listeria. PrfA proteins of L.

Regulated expression of HPrK/P does not affect carbon catabolite repression of the xyn operon and of rocG in Bacillus subtilis.

HPr kinase/phosphorylase (HPrK/P), a central metabolic regulator in many Gram-positive bacteria, reversibly phosphorylates HPr and Crh, thus controlling their activities as effectors of CcpA predominantly in carbon catabolite repression (CCR). We have placed the constitutively expressed hprK in its native chromosomal locus under anhydrotetracycline-dependent transcriptional control to establish the correlation between HPrK/P amounts and the efficiency of CCR in Bacillus subtilis. This resulted in about eightfold repression of HPrK/P expression but had no effect on CCR as monitored by xynP'-lacZ reporter gene expression and by analysis of RocG protein amounts.