In the absence of arabinose and interactions with other proteins, AraC, the activator-repressor that regulates the araBAD operon in Escherichia coli, was found to prefer participating in DNA looping interactions between the two well-separated DNA half-sites, araI1 and araO2 at their normal separation of 211 base-pairs rather than binding to these same two half-sites when they are adjacent to on...

The Bacillus subtilis araC locus, mapped at about 294 degrees on the genetic map, was defined by mutations conferring an Ara- phenotype to strains bearing the metabolic araA, araB, and araD wild-type alleles (located at about 256 degrees on the genetic map) and by mutants showing constitutive expression of the three genes. In previous work, it has been postulated that the gene in which these mu...

The comparative approach to the recognition of transcription regulatory sites is based on the assumption that as long as a regulator is conserved in several genomes, one can expect that sets of co-regulated genes (regulons) and regulatory sites for the regulator in these genomes are conserved as well. We used this approach to analyze the ribose (RbsR), arabinose (AraC), and xylose (XylR) regulo...

AraC Negative Regulators (ANR) suppress virulence genes by directly down-regulating AraC/XylS members in Gram-negative bacteria. In this study, we sought to investigate the distribution and molecular mechanisms of regulatory function for ANRs among different bacterial pathogens. We identified more than 200 ANRs distributed in diverse clinically important gram negative pathogens, including Vibri...

present data showing that the regulator of the A-factor cascade in Streptomyces griseus , AdpA, possesses related family members, and they determine both the sites to which AdpA binds and a consensus DNA-binding sequence. Sequence homologues and consensus DNA binding sites of regulatory proteins were first reported more than 20 years ago, so why is this new work notewor-thy? The answer is that ...

PURPOSE To improve survival and reduce toxicity in primary CNS lymphoma (PCNSL) treatment, we conducted a multicenter phase II study with early high-dose chemotherapy (HDT) and autologous stem-cell transplantation (ASCT) followed by hyperfractionated whole-brain radiotherapy (WBRT) for newly diagnosed PCNSL patients younger than 65 years of age. PATIENTS AND METHODS Chemotherapy included thre...

Frameshift mutations in a restricted portion of the arabinose operon regulatory gene araC from Escherichia coli give rise to active AraC protein, likely from the in vivo synthesis of two incomplete fragments that are active together. Synthesis of corresponding fragments, each separately inactive, from two plasmids within cells also resulted in complementation.

The arabinose-binding pockets of wild type AraC dimerization domains crystallized in the absence of arabinose are occupied with the side chains of Y31 from neighboring domains. This interaction leads to aggregation at high solution concentrations and prevents determination of the structure of truely apo AraC. In this work we found that the aggregation does not significantly occur at physiologic...

Intact AraC protein is poorly soluble and difficult to purify, whereas its dimerization domain is the opposite. Unexpectedly, the DNA binding domain of AraC proved also to be soluble in cells when overproduced and is easily purified to homogeneity. The DNA binding affinity of the DNA binding domain for its binding site could not be measured by electrophoretic mobility shift because of its rapid...

Arabinofuranosyl cytidine (AraC) is an analog of deoxycytidine used as anticancer drug for leukemic patients. The effective dose always produces severe complications. present study investigated the modulation autophagy and its impact on cytotoxicity AraC toward murine myelogenous leukemia cells (M-NFS-60). Autophagy was inhibited by NH4Cl or Bafilomycin A1 enhanced amino acid starvation, glucos...