Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ArsRS two-component system controls the pH-dependent transcription of several target genes involved in the acid resistance of Helicobacter pylori. In its phosphorylated form the response regulator ArsR activates transcription of the urease genes and it has been reported that ArsR approximately P binds to a 26 bp consensus motif which is present in the promoter regions of the ORFs hp1408, hp119 and hp1432 encoding proteins of unknown function. Here we show that the upstream region of ORF hp1408 exhibits considerable sequence variation in different isolates of H. pylori. By the construction of fusions of the P(1408) promoter from different H. pylori strains to the reporter gene gfp in the genetic background of H. pylori G27 we demonstrate that these sequence variations do not significantly affect acid-induced transcription. Furthermore, we show that a P(1408) core promoter comprising only the -10 promoter element and the 26 bp ArsR binding site overlapping the -35 region is sufficient for eliciting the normal acid response of ORF hp1408.
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PMID:Repeated sequence motifs in the Helicobacter pylori P1408 promoter do not affect its transcription. 1676 37

Cloning, sequencing and molecular characterisation of a cryptic plasmid, pUPTC237, from a urease-positive thermophilic Campylobacter (UPTC) isolate obtained from the natural environment in Northern Ireland is reported in this study. Based on the determined DNA sequence, the pUPTC237 DNA was identified as a circular molecule of 3828 bp with a G+C content of 29.5%. As with other plasmid DNAs from Gram-negative bacteria, pUPTC237 contained an A+T-rich region (A+T content: 95%), followed by multiple direct tandem repeat units of 22 bp, characteristic of a replication origin and iteron sequence. A possible open reading frame (ORF)-1 was located upstream of the A+T-rich region and the iteron sequence that encoded a 460 amino acid protein similar to the mobilisation (mob) protein and two putative promoter structure sequences at the -35 and -10 regions and a possible ribosome binding site occurred upstream of the start codon for the ORF-1. Moreover, three possible ORFs (a short ORF-2 encoding 26 amino acids, similar to repA; an ORF-3 encoding 341 amino acids, similar to repB; and an ORF-4 encoding 96 amino acids with unknown function) were also identified. There are also two putative promoter structures for these three ORFs at the -35 and -10 regions upstream of the possible ORF-2. A possible transcription termination region was identified downstream of ORF-4. Northern blot hybridisation analysis suggested that these four ORFs constitute an operon and generate a messenger RNA (mRNA) transcript.
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PMID:Cloning, sequencing and molecular characterisation of a cryptic plasmid from a urease-positive thermophilic Campylobacter (UPTC) isolate. 1763 41

Acid stress is the most obvious challenge Helicobacter pylori encounters in human stomach. The urease system is the basic process used to maintain periplasmic and cytoplasmic pH near neutrality when H. pylori is exposed to acidic condition. However, since the urea concentration in gastric juice is approximately 1 mM, considered possibly insufficient to ensure the survival of H. pylori, it is postulated that additional mechanisms of pH homeostasis may contribute to the acid adaptation in H. pylori. In order to identify the acid-related proteins other than the urease system we have compared the proteome profiles of H. pylori strain 26695 exposed to different levels of external pH (7.4, 6.0, 5.0, 4.0, 3.0, and 2.0) for 30 min in the absence of urea using 2-DE. Differentially expressed proteins were identified by MALDI-TOF-TOF-MS analysis, which turned out to be 36 different proteins. The functions of these proteins included ammonia production, molecular chaperones, energy metabolism, cell envelope, response regulator and some proteins with unknown function. SOM analysis indicated that H. pylori responds to acid stress through multi-mechanisms involving many proteins, which depend on the levels of acidity the cells encounter.
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PMID:The changes of proteomes components of Helicobacter pylori in response to acid stress without urea. 1860 4

The PVC superphylum is an amalgamation of species from the phyla Planctomycetes, Verrucomicrobia, and Chlamydiae, along with the Lentisphaerae, Poribacteria, and two other candidate divisions. The diverse species of this superphylum lack any significant marker that differentiates them from other bacteria. Recently, genome sequences for 37 species covering all of the main PVC groups of bacteria have become available. We have used these sequences to construct a phylogenetic tree based upon concatenated sequences for 16 proteins and identify molecular signatures in protein sequences that are specific for the species from these phyla or those providing molecular links among them. Of the useful molecular markers identified in the present work, six conserved signature indels (CSIs) in the proteins Cyt c oxidase, UvrD helicase, urease, and a helicase-domain containing protein are specific for the species from the Verrucomicrobia phylum; three other CSIs in an ABC transporter protein, cobyrinic acid ac-diamide synthase, and SpoVG protein are specific for the Planctomycetes species. Additionally, a 3 aa insert in the RpoB protein is uniquely present in all sequenced Chlamydiae, Verrucomicrobia, and Lentisphaerae species, providing evidence for the shared ancestry of the species from these three phyla. Lastly, we have also identified a conserved protein of unknown function that is exclusively found in all sequenced species from the phyla Chlamydiae, Verrucomicrobia, Lentisphaerae, and Planctomycetes suggesting a specific linkage among them. The absence of this protein in Poribacteria, which branches separately from other members of the PVC clade, indicates that it is not specifically related to the PVC clade of bacteria. The molecular markers described here in addition to clarifying the evolutionary relationships among the PVC clade of bacteria also provide novel tools for their identification and for genetic and biochemical studies on these organisms.
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PMID:Molecular Signatures for the PVC Clade (Planctomycetes, Verrucomicrobia, Chlamydiae, and Lentisphaerae) of Bacteria Provide Insights into Their Evolutionary Relationships. 2306 Aug 63

The phosphate-specific transport operon, pstSCAB-phoU, of Gram-negative bacteria is an essential part of the Pho regulon. Its key roles are to encode a high-affinity inorganic phosphate transport system and to prevent activation of PhoB in phosphate-rich environments. In general, mutations in pstSCAB-phoU lead to the constitutive expression of the Pho regulon. Previously, we constructed a pstCA deletion mutant of Citrobacter rodentium and found it to be attenuated for virulence in mice, its natural host. This attenuation was dependent on PhoB or PhoB-regulated gene(s) because a phoB mutation restored virulence for mice to the pstCA mutant. To investigate how downstream genes may contribute to the virulence of C. rodentium, we used microarray analysis to investigate global gene expression of C. rodentium strain ICC169 and its isogenic pstCA mutant when grown in phosphate-rich medium. Overall 323 genes of the pstCA mutant were differentially expressed by at least 1.5-fold compared to the wild-type C. rodentium. Of these 145 were up-regulated and 178 were down-regulated. Differentially expressed genes included some involved in phosphate homoeostasis, cellular metabolism and protein metabolism. A large number of genes involved in stress responses and of unknown function were also differentially expressed, as were some virulence-associated genes. Up-regulated virulence-associated genes in the pstCA mutant included that for DegP, a serine protease, which appeared to be directly regulated by PhoB. Down-regulated genes included those for the production of the urease, flagella, NleG8 (a type III-secreted protein) and the tad focus (which encodes type IVb pili in Yersinia enterocolitica). Infection studies using C57/BL6 mice showed that DegP and NleG8 play a role in bacterial virulence. Overall, our study provides evidence that Pho is a global regulator of gene expression in C. rodentium and indicates the presence of at least two previously unrecognized virulence determinants of C. rodentium, namely, DegP and NleG8.
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PMID:Genome-wide analysis of the Pho regulon in a pstCA mutant of Citrobacter rodentium. 2322 53


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