Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0149958 (complex partial seizures)
 2,563 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously reported the nucleotide sequence of the first six genes of the Streptococcus pneumoniae type 19F capsular polysaccharide biosynthesis locus (cps19f). In this study we used plasmid insertion/rescue and inverse polymerase chain reaction (PCR) to clone an additional 10 kb downstream region containing the remainder of the cps19f locus, which was then subjected to sequence analysis. The cps19f locus is located in the S. pneumoniae chromosome between dexB and aliA, and consists of 15 open reading frames (ORFs), designated cps19fA to cps19fO, that appear to be arranged as a single transcriptional unit. Insertion-duplication mutants in seven out of the nine new ORFs have been constructed in a smooth type 19F strain, all of which resulted in a rough (nonencapsulated) phenotype, confirming that the operon is essential for capsule production. Comparison with sequence databases has allowed us to propose functions for 12 of the cps19f gene products, and a biosynthetic pathway for type 19F capsular polysaccharide. T7 expression studies confirmed that cps19fH, cps19fK, cps19fL, cps19fM and cps19fN directed the production of polypeptides of the expected size in Escherichia coli. The function of the cps19fK product was confirmed by its ability to complement a mutation in nfrC (rffE) in E. coli, as judged by restoration of sensitivity to bacteriophage N4. Interestingly, the last four genes of the locus (cps19fL-O) exhibit very strong homology (up to 70% amino acid identity) to a portion of the Shigella flexneri rfb gene cluster encoding biosynthesis of dTDP-rhamnose. When expressed in E. coli, cps19fL-O were capable of complementing a mutation deleting the respective Shigella flexneri homologues. Southern hybridization analysis indicated that cps19fA and cps19fB were the only cps genes found in all 16 S. pneumoniae serotypes/groups tested. The region from cps19fG to cps19fK was found only in members of serogroup 19, and, within this, cps19fl was unique to type 19F.
Mol Microbiol 1997 Feb
PMID:Characterization of the locus encoding the Streptococcus pneumoniae type 19F capsular polysaccharide biosynthetic pathway. 915 46

The RcsA and RcsB proteins of Erwinia amylovora and Escherichia coli were expressed in E. coli and purified. Their DNA-binding activity was examined using a 1-kb DNA region containing the putative promoter of the ams operon of Ew. amylovora, which is responsible for the biosynthesis of the exopolysaccharide amylovoran. Mobility shift assays indicated specific binding of RcsA and RcsB to a region of 78 bp spanning nucleotide positions -578 to -501 relative to the translational start of the first open reading frame of the operon. This region includes stretches of homology to E. coli sigma 70 promoter consensus sequences and to the E. coli cps promoter region. Binding of the Rcs proteins was not found at a JUMPstart consensus, typical for various promoters of polysaccharide gene clusters. DNA-binding activity was not detected for RcsA alone and only high concentrations of RcsB were able to interact with the ams promoter in our assay. The two proteins bind cooperatively at the indicated region of the ams promoter and further evidence is provided showing that the DNA-protein complex formed involves a heterodimer of RcsA and RcsB. The specific activity of RcsA, but not of RcsB, was enhanced when the protein was expressed in E. coli at 28 degrees C, relative to expression at 37 degrees C. In addition, DNA-protein complex formation is affected by temperature. The E. coli RcsA/RcsB proteins bind to the same region of the ams promoter and are able to interact with the Rcs proteins from Ew. amylovora.
Mol Gen Genet 1997 Sep
PMID:Interaction of the regulator proteins RcsA and RcsB with the promoter of the operon for amylovoran biosynthesis in Erwinia amylovora. 934 81

The membrane-anchored DjIA protein represents the third member of the DnaJ 'J-domain' family of Escherichia coli that includes DnaJ and CbpA. DjIA possesses a J-domain at its extreme C-terminus but shares no additional homology with DnaJ. Our genetic analysis suggests that DjIA acts in concert with the RcsB/C two-component signal transduction system to augment induction of the cps (capsular polysaccharide) operon and synthesis of colanic acid mucoid capsule. The DjIA J-domain is essential for the observed stimulation of this pathway as deletion, or introduction of the mutation H233Q, within the highly conserved HPD tripeptide abolished all inducing activity. Deletion of the transmembrane anchor sequence also abolished all inducing activity. djIA is not an essential gene under all conditions tested, nor is it essential for mucoid capsule biosynthesis; however, strong overexpression leads to rapid loss of cell viability suggesting that the gene is normally tightly regulated. Northern analysis revealed that djIA message was extremely unstable but could be induced or stabilized in response to cold shock. The activation of the cps operon by DjIA is dependent upon both DnaK(Hsp70) and GrpE, and therefore we propose a role for DjIA, together with this chaperone machine, as a novel regulator of a two-component histidine kinase signal transduction pathway.
Mol Microbiol 1997 Sep
PMID:Positive control of the two-component RcsC/B signal transduction network by DjlA: a member of the DnaJ family of molecular chaperones in Escherichia coli. 936 17

DjIA is a novel DnaJ-like protein localized to the inner membrane of Escherichia coli through the single transmembrane domain (TMD) found at the N-terminus. The overproduction of DjIA activates expression of the cps operon, controlling synthesis and export of the extracellular polysaccharide colanic acid via the Rcs/B two-component signal transduction pathway. We now show that both the TMD and the J-region are essential for the induction of cps expression observed with the overproduction of DjIA. Furthermore, we describe the isolation and characterization of different point mutations in the TMD that completely or partially block the induction of cps expression associated with overproduction of DjIA. These mutations were shown not to affect the localization, stability or topology of the mutant DjIA proteins. We propose that these mutations are affecting specific interactions between the TMD of DjIA and its substrate protein(s), for example RcsC, the membrane sensor kinase partner of the Rcs/B signal transduction pathway.
Mol Microbiol 1997 Sep
PMID:Point mutations in the transmembrane domain of DjlA, a membrane-linked DnaJ-like protein, abolish its function in promoting colanic acid production via the Rcs signal transduction pathway. 936 18

Escherichia coli group I capsular K antigens are found in two forms on the cell surface. The K(LPS) form is linked to lipopolysaccharide lipid A core, whereas the high-molecular-weight capsular form is assembled independently of lipid A core. Subgroup IB K antigens are generally co-expressed with either the O8 or O9 antigen and, under the appropriate conditions, with the exopolysaccharide, colanic acid. To examine the relationships between the genetic loci and the synthetic pathways for these various cell-surface polymers, the gene cluster responsible for expression of a prototype group IB K antigen (serotype K40) was cloned and the flanking chromosomal regions characterized. Analysis of the six orfs within the cluster indicates features typical of Wzy (Rfc)-dependent O antigens. Synthesis of group IB K antigens is initiated by WecA (Rfe), a UDP-GlcNAc::undecaprenylphosphate GlcNAc-1-phosphate transferase, and the chain length of K40LPS is determined by the wzz gene product. The his-region of the E. coli O8:K40 prototype is almost exclusively devoted to the expression of three different surface polysaccharides. The rfbK40 cluster is located adjacent to the cps (colanic acid synthesis) and rfbO8 (O8 antigen synthesis) loci in the gene order: his-rfbO8/O9-wzz-ugd-gnd-rfbK40-galF-cps. Thus, rfbK40 is in the location occupied by other Wzy-dependent rfb gene clusters, and rfbO8/O9 represents an additional locus.
Mol Microbiol 1997 Oct
PMID:Molecular and functional analysis of genes required for expression of group IB K antigens in Escherichia coli: characterization of the his-region containing gene clusters for multiple cell-surface polysaccharides. 938 97

Gamma-aminobutyric acid (GABA) plays a pivotal role in suppressing the origin and spread of seizure activity. Low occipital lobe GABA was associated with poor seizure control in patients with complex partial seizures. Vigabatrin irreversibly inhibits GABA-transaminase, raising brain and cerebrospinal fluid (CSF) GABA concentrations. The effect of vigabatrin on occipital lobe GABA concentrations was measured by in vivo nuclear magnetic-resonance spectroscopy. Using a single oral dose of vigabatrin, the rate of GABA synthesis in human brain was estimated at 17% of the Krebs cycle rate. As the daily dose of vigabatrin was increased to up to 3 g, the fractional elevation of brain GABA was similar to CSF increase. Doubling the daily dose from 3 to 6 g failed to increase brain GABA further. Increased GABA concentrations appear to reduce GABA synthesis in humans as it does in animals. With traditional antiepileptic drugs, remission of the seizure disorder was associated with normal GABA levels. With vigabatrin, elevated CSF and brain GABA was associated with improved seizure control. Vigabatrin enhances the vesicular and nonvesicular release of GABA. The release of GABA during seizures may be mediated in part by transporter reversal that may serve as an important protective mechanism. During a seizure, this mechanism may be critical in stopping the seizure or preventing its spread.
Mol Neurobiol 1998 Feb
PMID:Measuring human brain GABA in vivo: effects of GABA-transaminase inhibition with vigabatrin. 955 4

The group 1 K30 antigen from Escherichia coli (O9a:K30) is present on the cell surface as both a capsular structure composed of high-molecular-weight K30 polysaccharide and as short K30 oligosaccharides linked to lipid A-core in a lipopolysaccharide molecule (K30LPS). To determine the molecular processes that are responsible for the two forms of K antigen, the 16 kb chromosomal cps region has been characterized. This region encodes 12 gene products required for the synthesis, polymerization and translocation of the K30 antigen. The gene products include four glycosyltransferases responsible for synthesis of the K30 repeat unit; a PST (1) exporter (Wzx), required to transfer lipid-linked K30 units across the plasma membrane to the periplasmic space; and a K30-antigen polymerase (Wzy). These gene products are typical of those seen in O-antigen biosynthesis gene clusters and they interact with the lipopolysaccharide translocation pathway to express K30LPS on the cell surface. The same gene products also provide the biosynthetic intermediates for the capsule assembly pathway, although they are not in themselves sufficient for synthesis of the K30 capsule. Three additional genes, wza, wzb and wzc, encode homologues to proteins that are encoded by gene clusters involved in expression of a variety of bacterial exopolysaccharides. Mutant analysis indicates that Wza and Wzc are required for wild-type surface expression of the capsular structure but are not essential for polymerization and play no role in the translocation of K30LPS. These surface expression components provide the key feature that distinguishes the assembly systems for O antigens and capsules.
Mol Microbiol 1999 Mar
PMID:Gene products required for surface expression of the capsular form of the group 1 K antigen in Escherichia coli (O9a:K30). 1020 Sep 54

Genes rcsC and rcsB form a two-component system in which rcsC encodes the sensor element and rcsB the regulator. In Escherichia coli, the system positively regulates the expression of the capsule operon, cps, and of the cell division gene ftsZ. We report the identification of the promoter and of the sequences required for rcsB-dependent stimulation of ftsZ expression. The promoter, ftsA1p, located in the ftsQ coding sequence, co-regulates ftsA and ftsZ. The sequences required for rcsB activity are immediately adjacent to this promoter.
Mol Microbiol 1999 Nov
PMID:Regulation of Escherichia coli cell division genes ftsA and ftsZ by the two-component system rcsC-rcsB. 1056 86

The opioid peptide dynorphin is thought to be implicated in specific types of seizures. In particular, complex partial seizures have been shown to cause release of dynorphin, activation of prodynorphin gene expression, and new peptide synthesis in the hippocampus. In this study, the kinetics of the seizure-induced changes in prodynorphin mRNA and ir-dynorphin A levels in the hippocampus have been compared with those induced in the temporal and frontal cortex, i.e., in other regions involved in the pathophysiology of complex partial seizures. Experiments have been run using kindling, one of the most valuable models of partial epilepsy. In the hippocampus (1) prodynorphin mRNA levels transiently increase (threefold) 1 h after kindled seizures, and return to baseline by 2 h, and (2) dynorphin A levels are slightly decreased at 1 h, but increase (twofold) at 2 h and return to baseline by 6 h. In the temporal and in the frontal cortex, a late (beginning at 2 h) and prolonged (up to 24 h) decrease in both prodynorphin mRNA and ir-dynorphin A levels have been observed. These data suggest that differential changes in dynorphin metabolism occur in different brain areas after seizures. The mechanisms and functional implications of this observation remain to be investigated.
J Mol Neurosci
PMID:Region-specific changes in prodynorphin mRNA and ir-dynorphin A levels after kindled seizures. 1069 Dec 94

The microPET R4 scanner is a dedicated positron emission tomograph (PET) for studies of rodents. A number of scanner parameters such as spatial resolution, sensitivity, scatter, and count rate performance were determined in this work, which showed that the microPET R4 is a suitable PET scanner for small animals like mice and rats. In the center of the field of view (FOV) a maximal sensitivity of 43.66 cps/kBq for a centered point source was calculated from a measurement with a germanium-68 line source within an energy widow of 250-750 keV. A spatial resolution of 1.85 mm full-width at half-maximum (FWHM) in the axial direction and 1.66 mm FWHM in the transaxial direction was measured in the center with a 1-mm-diameter sodium-22 point source. Within the inner 20 mm of the FOV the volumetric resolution is better than 15.6 micro l, corresponding to a linear resolution of less than 2.5 mm in all three dimensions. Images of a high-resolution phantom and from mice and rat studies illustrate the good performance of the scanner. A maximal noise equivalent count rate (NECR) was reached at 174 kcps for a mouse phantom and at 93 kcps for a rat phantom (energy window 250-750 keV). Scatter fractions were measured between 0.30 and 0.42 for an energy window of 250-750 keV and phantom diameters similar to mice and rats. A comparison with the microPET P4 model for primates illustrates the gain in sensitivity due to a smaller detector ring diameter but also the changes in NECR.
Eur J Nucl Med Mol Imaging 2003 May
PMID:Performance evaluation of the microPET R4 PET scanner for rodents. 1253 44


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