Redox signal transduction: mutations shifting [2Fe-2S] centers of the SoxR sensor-regulator to the oxidized form.

SoxR is a [2Fe-2S] transcription factor triggered by oxidative stress and activated in vitro by one-electron oxidation or assembly of the iron-sulfur centers. To distinguish which mechanism operates in cells, we studied constitutively active SoxR (SoxRc) proteins. Three SoxRc proteins contained [2Fe-2S] centers required for in vitro transcription and, like wild-type SoxR, were inactivated by chemical reduction.

The redox state of the [2Fe-2S] clusters in SoxR protein regulates its activity as a transcription factor.

SoxR protein is a redox-responsive transcription factor that governs a regulon of oxidative stress and antibiotic resistance genes in Escherichia coli. Purified SoxR contains oxidized [2Fe-2S] clusters and stimulates in vitro transcription of its target gene soxS up to 100-fold. SoxR transcriptional activity, but not DNA binding, is completely dependent on the [2Fe-2S] clusters; apo-SoxR prepared in vitro binds the soxS promoter with unchanged affinity but does not have transcription activity.

Anesthetic efficacy of eutectic prilocaine-lidocaine cream in pediatric oncology patients undergoing lumbar puncture.

Objective: To evaluate the efficacy of eutectic mixture of local anesthetics 5% (Emla) in reducing pain associated with lumbar punctures in children.

Design: Prospective, double-blind, randomized, placebo-controlled trial.

Setting: University pediatric hospital.

Errors evolution and analysis in antineoplastic drug preparation during one year.

We analyzed the errors occurring in the preparation circuit of cytotoxic mixtures of the Centralized Cytotoxic Preparation Unit during one year. Analysis of their evolution meant the investigation of twenty parameters susceptible to error. Each parameter was considered one error opportunity.

Activation of SoxR-dependent transcription in vitro by noncatalytic or NifS-mediated assembly of [2Fe-2S] clusters into apo-SoxR.

SoxR is a transcriptional activator that senses superoxide and nitric oxide stress in Escherichia coli. The active protein isolated from E. coli contains a pair of [2Fe-2S] clusters per SoxR dimer.

A second Escherichia coli gene with similarity to gapA.

An open reading frame has been found downstream of the ald gene at 31 min in the Escherichia coli chromosome and has been designated gapC because of its high similarity with gapA (min 39, encoding glyceraldehyde-3-phosphate dehydrogenase), and with gapB (min 62, a gene with high similarity to gapA, encoding erythrose-4-phosphate dehydrogenase). The gapC gene (min 31) encodes a polypeptide of 204 amino acids, 126 residues shorter than glyceraldehyde-3-phosphate dehydrogenase. In this 204-codon open reading frame several amino acids important for catalysis are conserved.

Binuclear [2Fe-2S] clusters in the Escherichia coli SoxR protein and role of the metal centers in transcription.

SoxR protein of Escherichia coli is activated by superoxide-generating agents or nitric oxide as a powerful transcription activator of the soxS gene, whose product activates approximately 10 other promoters. SoxR contains non-heme iron essential for abortive initiation of transcription in vitro. Here we show that this metal dependence extends to full-length transcription in vitro.

Nickel availability to pea (Pisum sativum L.) plants limits hydrogenase activity of Rhizobium leguminosarum bv. viciae bacteroids by affecting the processing of the hydrogenase structural subunits.

Rhizobium leguminosarum bv. viciae UPM791 induces the synthesis of an [NiFe] hydrogenase in pea (Pisum sativum L.) bacteroids which oxidizes the H2 generated by the nitrogenase complex inside the root nodules.

An iron-sulfur center essential for transcriptional activation by the redox-sensing SoxR protein.

The soxRS oxidative stress regulon of Escherichia coli is triggered by superoxide (O2.-) generating agents or by nitric oxide through two consecutive steps of gene activation. SoxR protein has been proposed as the redox sensing gene activator that triggers this cascade of gene expression.

High similarity among the tomato yellow leaf curl virus isolates from the west Mediterranean basin: the nucleotide sequence of an infectious clone from Spain.

An isolate of tomato yellow leaf curl geminivirus, from the first epidemic outbreaks that occurred in Murcia, Spain (TYLCV-M) in 1992, was cloned and its nucleotide sequence was determined. The circular single stranded DNA consisted of 2777 nucleotides. The genome organization resembled that of other TYLCV sequenced so far; regulatory signal sequences for bidirectional transcription and for polyadenylation of the transcripts were localized in the sequence.

Negative autoregulation by the Escherichia coli SoxS protein: a dampening mechanism for the soxRS redox stress response.

The soxRS redox stress regulon of Escherichia coli is triggered in two stages, with the activated SoxR protein stimulating the soxS gene, whose product then triggers transcription of approximately 10 promoters. Genetic and biochemical experiments presented here show that SoxS protein also limits soxS transcription in vivo and binds the soxS promoter in vitro.

Sequencing and characterization of a gene cluster encoding the enzymes for L-rhamnose metabolism in Escherichia coli.

The sequencing of the EcoRI-HindIII fragment complementing mutations in the structural genes of the L-rhamnose regulon of Escherichia coli has permitted identification of the open reading frames corresponding to rhaB, rhaA, and rhaD. The deduced amino acid sequences gave a 425-amino-acid polypeptide corresponding to rhamnulose kinase for rhaB, a 400-amino-acid polypeptide corresponding to rhamnose isomerase for rhaA, and a 274-amino-acid polypeptide corresponding to rhamnulose-1-phosphate aldolase for rhaD. Transcriptional fusions of the three putative promoter regions to lacZ showed that only the rhaB leader region acted as a promoter, as indicated by the high beta-galactosidase activity induced by rhamnose, while no significant activity from the rhaA and rhaD constructions was detected.

Molecular analysis of a microaerobically induced operon required for hydrogenase synthesis in Rhizobium leguminosarum biovar viciae.

The nucleotide sequence (6138 bp) of a microaerobically inducible region (hupV/VI) from the Rhizobium leguminosarum bv. viciae hydrogenase gene cluster has been determined. Six genes, arranged as a single operon, were identified, and designated hypA, B, F, C, D and E based on the sequence similarities of all of them, except hypF, to genes from the hydrogenase pleiotropic operon (hyp) from Escherichia coli.

Nucleotide sequence and organization of an H2-uptake gene cluster from Rhizobium leguminosarum bv. viciae containing a rubredoxin-like gene and four additional open reading frames.

The nucleotide sequence of a 3.2 kb region following the hydrogenase structural operon (hupSLCDEF) in the H2-uptake gene cluster from Rhizobium leguminosarum by viciae strain 128C53 has been determined. Five closely linked genes encoding products of 16.

Two-stage control of an oxidative stress regulon: the Escherichia coli SoxR protein triggers redox-inducible expression of the soxS regulatory gene.

Escherichia coli responds to the redox stress imposed by superoxide-generating agents such as paraquat by activating the synthesis of as many as 80 polypeptides. Expression of a key group of these inducible proteins is controlled at the transcriptional level by the soxRS locus (the soxRS regulon). A two-stage control system was hypothesized for soxRS, in which an intracellular redox signal would trigger the SoxR protein as a transcriptional activator of the soxS gene and the resulting increased levels of SoxS protein would activate transcription of the various soxRS regulon genes (B.

Nucleotide sequence and characterization of four additional genes of the hydrogenase structural operon from Rhizobium leguminosarum bv. viciae.

The nucleotide sequence of a 2.5-kbp region following the hydrogenase structural genes (hupSL) in the H2 uptake gene cluster from Rhizobium leguminosarum bv. viciae UPM791 was determined.

Inactivation of propanediol oxidoreductase of Escherichia coli by metal-catalyzed oxidation.

1,2-Propanediol oxidoreductase, which reduces the L-lactaldehyde formed in the fermentation of L-fucose or L-rhamnose to L-1,2-propanediol in E. coli, was inactivated by a component of E. coli cell extracts in the presence of oxygen.

Molecular cloning and DNA sequencing of the Escherichia coli K-12 ald gene encoding aldehyde dehydrogenase.

The gene ald, encoding aldehyde dehydrogenase, has been cloned from a genomic library of Escherichia coli K-12 constructed with plasmid pBR322 by complementing an aldehyde dehydrogenase-deficient mutant. The ald region was sequenced, and a single open reading frame of 479 codons specifying the subunit of the aldehyde dehydrogenase enzyme complex was identified. Determination of the N-terminal amino acid sequence of the enzyme protein unambiguously established the identity and the start codon of the ald gene.

Bronchial migration of pulmonary arterial coil.

Transcatheter embolization was performed with stainless steel coils in a patient with bilateral pulmonary arterial aneurysms of unknown etiology. After a successful initial procedure, endobronchial migration of one of the coils was found which required surgical treatment. Indications of embolization and different types of materials are discussed.

Oxygen regulation of L-1,2-propanediol oxidoreductase activity in Escherichia coli.

Regardless of the respiratory conditions of the culture, Escherichia coli synthesizes an active propanediol oxidoreductase. Under anaerobic conditions, the enzyme remained fully active and accomplished its physiological role, while under aerobic conditions, it was inactivated in a process that did not depend on protein synthesis or on the presence of a carbon source.