The L-arabinose operon in Escherichia coli is a model system for the study of the control of gene expression. Maximal expression of the araBAD operon requires two positive control components: the araC protein-L-arabinose complex and the cyclic AMP receptor protein-cyclic AMP complex. Both araC protein and cyclic AMP receptor protein are required for the initiation of transcription of araBAD mRN...

AraC protein, the regulator of the l-arabinose operon in Escherichia coli has been postulated to function by a light switch mechanism. According to this mechanism, it should be possible to find mutations in the DNA-binding domain of AraC that result in weaker arm-DNA-binding domain interactions and which make the protein constitutive, that is, it no longer requires arabinose to activate transcr...

A total of 68 adult patients with B-cell acute lymphoblastic leukemia (B-ALL) were treated in three consecutive adult multicenter ALL studies. The diagnosis of B-ALL was confirmed by L3 morphology and/or by surface immunoglobulin (Slg) expression with > 25% blast cell infiltration in the bone marrow (BM). They were characterized by male predominance (78%) and a median age of 34 years (15 to 65 ...

The AraC-XylS database contains information about a family of positive transcriptional regulators broadly distributed in bacteria. This specific database focuses on protein sequences and on the biological and functional features of each of the proteins that belong to this family. Each entry provides information on the protein itself, the annotated protein sequence and, when the crystal is avail...

The prognosis of patients with central nervous system relapse of aggressive lymphoma is very poor with no therapy established so far. In a prospective multicenter phase II study, we evaluated a potentially curative chemotherapy-only regimen in these patients. Adult immunocompetent patients 65 years of age or under received induction chemotherapy with MTX/IFO/DEP (methotrexate 4 g/m(2) intraveno...

Editor's Note: These short, critical reviews of recent papers in the Journal, written exclusively by graduate students or postdoctoral fellows, are intended to summarize the important findings of the paper and provide additional insight and commentary. For more information on the format and purpose of the Journal Club, please see Review of Breton-Provencher et al. Processing olfactory informati...

Strains were constructed that contain mutational alterations affecting two distinct functional domains within the araC gene protein. The araCi (catabolite repression insensitivity) and araCh (catabolite repression hypersensitivity) mutations were used to alter the catabolite repression sensitivity domain, and mutation to D-fucose resistance was used to alter the inducer binding domain. araCh, D...

The previously isolated hemiplegic, induction-negative, repression-positive mutants, H80R and Y82C, were found to be defective in the binding of arabinose. Randomization of other residues close to arabinose in the three-dimensional structure of AraC or that make strong interactions with arabinose yielded induction-negative, repression-positive mutants. The induction and repression properties of...

GENERAL BACKGROUND Escherichia coli can grow on L-arabinose as a source of carbon and energy (Fig. 1) (Schleif, 1996). Not surprisingly, because the amounts of enzymes required to convert arabinose into a component of the pentose phosphate shunt are significant, the levels of the enzymes are regulated. In the absence of arabinose, the uninduced or basal level of expression of the proteins is ab...