Growth by Insertion: The Family of Bacterial DDxP Proteins.

We have identified a variety of proteins in species of the Legionella, Aeromonas, Pseudomonas, Vibrio, Nitrosomonas, Nitrosospira, Variovorax, Halomonas, and Rhizobia genera, which feature repetitive modules of different length and composition, invariably ending at the COOH side with Asp-Asp-x-Pro (DDxP) motifs. DDxP proteins range in size from 900 to 6200 aa (amino acids), and contain 1 to 5 different module types, present in one or multiple copies. We hypothesize that DDxP proteins were modeled by the action of specific endonucleases inserting DNA segments into genes encoding DDxP motifs. Target site duplications (TSDs) formed upon repair of staggered ends generated by endonuclease cleavage would explain the DDxP motifs at repeat ends. TSDs acted eventually as targets for the insertion of more modules of the same or different types. Repeat clusters plausibly resulted from amplification of both repeat and flanking TSDs. The proposed growth shown by the insertion model is supported by the identification of homologous proteins lacking repeats in Pseudomonas and Rhizobium. The 85 DDxP repeats identified in this work vary in length, and can be sorted into short (136-215 aa) and long (243-304 aa) types. Conserved Asp-Gly-Asp-Gly-Asp motifs are located 11-19 aa from the terminal DDxP motifs in all repeats, and far upstream in most long repeats.

Relationship between serum mono-hydroxy-carbazepine concentrations and adverse effects in patients with epilepsy on high-dose oxcarbazepine therapy.

PURPOSE: To investigate the relationship between the serum concentration of the mono-hydroxy-derivative (MHD) of oxcarbazepine (OXC) and adverse effects (AEs) in epileptic patients on high-dose OXC therapy. PATIENTS AND METHODS: Forty-four consecutive patients, aged 18-65 years, with refractory epilepsy receiving OXC dosages > or = 1500 mg/day (range 1500-3300 mg/day) were assessed at an outpatient clinic. Serum MHD concentrations were determined by a specific HPLC assay in samples collected before the morning dose and 2 h after drug intake. An independent observer assessed AEs at each sampling time. RESULTS: AEs were reported in five patients at the first sampling time, and in 26 patients at the second sampling time. Nystagmus, sedation, blurred vision, and dizziness were the most frequent AEs. MHD concentrations (means +/- S.D.) associated with AEs were 29.6 +/- 5.58 compared with 21.7 +/- 5.0 mg/L when no AEs were detected (p = 0.0001). AEs were minimized in most patients by reducing OXC dose, increasing the number of daily administrations, or both. CONCLUSION: Patients with serum MHD concentrations > or = 30 mg/L are at greater risk of developing AEs. In many patients, AEs occur intermittently in relation to fluctuations in serum MHD. Monitoring MHD concentrations could help in the management of patients on high-dose OXC therapy.

A novel intragenic sequence enhances initiator-dependent transcription in human embryonic kidney 293 cells.

In a variety of Drosophila TATA-less promoters, transcription is directed by initiator (Inr) sequences, which are faithfully and efficiently recognized only when flanked 3' by the downstream promoter element (DPE). This motif, which is conserved at approximately 30 bp from the RNA start site, is viewed as a downstream counterpart to the TATA box, and is recognized by the general transcription factor (TF) IID. By transient expression assays in human embryonic kidney 293 cells, we show that DE1 (distal element 1), a DNA motif located at residues +23 to +29, sustains faithful Inr-dependent transcription as efficiently as the DPE. Transcription significantly increased when DE1 and DPE sequences were adjacently placed on the same template. Results emerging from in vivo RNA analyses matched electrophoretic mobility shift assay data. In agarose-electrophoretic mobility shift assays, retarded DNA-protein complexes resulting from the interaction of human holo-TFIID with either Inr(+)/DPE(+) or Inr(+)/DE1(+) promoters were formed at comparable levels, whereas binding of TFIID to both DE1 and DPE motifs was 2-fold increased. The strict requirement for spacing between the Inr and DPE was not observed for DE1, as locating the motif 4 bp away from the +1 site did not impair transcriptional enhancement. DE1 sequences may be common to many promoters and be overlooked because of their poor sequence homology.