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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Escherichia coli treA gene encodes an osmotically inducible periplasmic trehalase. A strain carrying a treA-lacZ transcriptional fusion was constructed. The beta-galactosidase activity produced in this strain growing exponentially in a medium of high osmotic pressure was 10-fold higher than that produced in a medium of low osmotic pressure, demonstrating that treA transcription is osmotically inducible. treA transcriptional induction depends neither on the presence of trehalase itself nor on the synthesis of cytoplasmic trehalose which occurs in response to osmotic stress in wild-type E. coli strains. The treA promoter was identified by S1 nuclease protection. Deletion analysis demonstrated that sequences sufficient for the osmotic induction lie downstream from nucleotide -40 with respect to the transcription start. Transcription initiation at treAp required the presence of a functional sigma 70 subunit of RNA polymerase. treA expression was increased in the presence of a mutation in osmZ, which was previously identified as leading to a partially constitutive expression of the osmotically inducible proU operon.
Mol Microbiol 1991 Mar
PMID:Osmotic induction of the periplasmic trehalase in Escherichia coli K12: characterization of the treA gene promoter. 171 Jul 60

Two soybean ribulose-1,5-bisphosphate carboxylase small subunit (SSU) genes, SRS1 and SRS4, are highly homologous over a region that includes 4 kb of 5' and 1 kb of 3' flanking sequences. The expression of these genes was compared using synthetic oligonucleotide probes. Analysis of a soybean leaf cDNA library indicates that SRS1 and SRS4 are the most highly expressed members of the soybean SSU gene family. Similar changes were observed in the RNA levels for these genes in response to white light, far-red light and darkness, although SRS1 was expressed at a four-fold higher level in total RNA than SRS4 under all conditions. However, nuclear run-on assays indicate that SRS1 is transcribed at a lower rate than SRS4, which suggests that SRS1 RNA is more stable. S1 nuclease analysis and oligonucleotide directed RNase H cleavage indicate that transcripts from both genes are polyadenylated within two principle regions separated by 35 nt. Sequence analysis of 16 independent cDNA clones identified seven different polyadenylation sites, and six of these sites lie within these two regions. Although SRS1 RNA was poorly recovered during poly(A)+ fractionation, RNase H cleavage experiments showed that transcripts from SRS1 and SRS4 had similar poly (A) tail lengths ranging from 0 to 220 nt. In addition, and despite differences in the untranslated leader sequences, SRS1 and SRS4 RNAs are assembled into polysomes with equal efficiencies. The overall similarity in expression patterns for these two genes further illustrates the coordinate evolution of individual members of a SSU gene family and is consistent with the proposal that gene conversion homogenizes both the coding and regulatory regions of these genes.
Plant Mol Biol 1990 Jun
PMID:Comparison of the expression of two highly homologous members of the soybean ribulose-1,5-bisphosphate carboxylase small subunit gene family. 171 10

osmC, an osmotically inducible gene of Escherichia coli, was physically mapped on the bacterial chromosome, cloned on multicopy plasmids, and its product, OsmC, was identified as a 14 kDa protein in maxicells. The DNA sequence of the gene and its upstream region were determined. The sequence of an osmC-phoA gene fusion confirmed the osmC reading frame. A deletion of osmC from the E. coli chromosome was constructed by gene replacement, demonstrating that it is not an essential gene. The osmCp promoter region was subcloned and a lac operon fusion transcribed under osmCp control was constructed. The expression of this operon fusion demonstrated that osmC regulation occurs at the transcriptional level. S1 nuclease protection experiments and deletion analysis identified two overlapping promoters with transcription start sites separated by ten nucleotides. All the sequences necessary for osmotic regulation of both promoters are located within a 137 base-pair DNA fragment extending from position -95 to +42 with respect to the putative osmC translation start. Two deletions were obtained that abolish the functioning of the upstream promoter. Yet, under our experimental conditions, the subsequent expression of the osmC-lacZ fusion was equivalent to that obtained from the tandem promoters. Mutations leading to constitutive expression of osmC were selected. Two independent mutations were obtained, both affected osmZ, the gene encoding the histone-like protein H1.
J Mol Biol 1991 Aug 20
PMID:Osmotic induction of gene osmC expression in Escherichia coli K12. 171 7

The formation of estrogens from C19 steroids is catalyzed by a specific form of cytochrome P450, aromatase cytochrome P450 (P450AROM; the product of the CYP19 gene). Previous studies have demonstrated that aromatase activity in human adipose and ovarian granulosa cells is subject to complex multifactorial regulation and that changes in activity are correlated with changes in the levels of mRNA encoding P450AROM. We have previously isolated the human CYP19 gene. Two unique untranslated first exons (exons I.1 and I.2) have been identified in mRNA specific for P450AROM in human placenta. Although the proportion of transcripts encoding exon I.2 is very small, genomic clones encoding the sequences of both exons I.1 and I.2 have recently been isolated. The corpus luteum of human ovary differs in that promoters I.1 and I.2 are completely inactive. Sequence analysis of the DNA immediately 5' of exon II (which contains the start site of translation) demonstrates the presence of a TATAA sequence beginning 149 basepairs 5' of the ATG initiation codon identified in placental exon II. Using a combination of primer extension and S1 nuclease protection analysis, it appears that the initiation site of ovarian P450AROM transcripts aligns 26 basepairs down-stream of the sequence TATAA. It appears, therefore, that the expression of P450AROM-specific mRNA in corpus luteum is regulated by an additional promoter (promoter II), which is located just 5' of exon II. Consistent with these observations, Northern analysis of poly(A)+ RNA isolated from placenta and corpus luteum demonstrates that the major promoter of placental P450AROM is promoter I.1, while the major promoter in the corpus luteum is promoter II.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Endocrinol 1991 Dec
PMID:Tissue-specific promoters regulate aromatase cytochrome P450 gene expression in human ovary and fetal tissues. 172 89

Site-directed mutations were introduced in the connecting loops and one of the two stem regions of the RNA pseudoknot in the tRNA-like structure of turnip yellow mosaic virus RNA. The kinetic parameters of valylation for each mutated RNA were determined in a cell-free extract from wheat germ. Structure mapping was performed on most mutants with enzymic probes, like RNase T1, nuclease S1 and cobra venom ribonuclease. An insertion of four A residues in the four-membered connecting loop L1 that crosses the deep groove of the pseudoknot reduces aminoacylation efficiency. Deletions up to three nucleotides do not affect aminoacylation or RNA pseudoknot formation. Deletion of the entire loop abolishes aminoacylation. Although elimination of the pseudoknot is presumed, this could not be demonstrated. Unlike the mutations in loop L1, all mutations in the three-membered connecting loop L2 that crosses the shallow groove of the RNA pseudoknot decrease the aminoacylation efficiency considerably. Nonetheless, the RNA pseudoknot is still present in most mutated RNAs. These results indicate that a number of mutations can be introduced in both loops without abolishing aminoacylation. Results obtained with the introduction of mismatches and A.U base-pairs in stem S1 of the pseudoknot, containing three G.C base-pairs in wild-type RNA, indicate that the pseudoknot is only marginally stable. Our estimation of the gain of free energy due to the pseudoknot formation is at most 2.0 kcal/mol. The pseudoknot structure can, however, be stabilized upon binding the valyl-tRNA synthetase.
J Mol Biol 1992 Jan 05
PMID:Mutational analysis of the pseudoknot in the tRNA-like structure of turnip yellow mosaic virus RNA. Aminoacylation efficiency and RNA pseudoknot stability. 173 Oct 70

Human hepatitis delta virus (HDV) RNA has been shown to contain a self-catalyzed cleavage activity. The sequence requirement for its catalytic activity appears to be different from that of other known ribozymes. In this paper, we define the minimum contiguous sequence and secondary structure of the HDV genomic RNA required for the catalytic activity. By using nested-set deletion mutants, we have determined that the essential sequence for the catalytic activity is contained within no more than 85 nucleotides of HDV RNA. These results are in close agreement with the previous determinations and confirmed the relative insignificance of the sequence at the 5' side of the cleavage site. The smallest catalytic RNA, representing HDV genomic RNA nucleotide positions 683 to 770, was used as the basis for studying the secondary structure requirements for catalytic activity. Analysis of the RNA structure, using RNase V1, nuclease S1 and diethylpyrocarbonate treatments showed that this RNA contains at least two stem-and-loop structures. Other larger HDV RNA subfragments containing the catalytic activity also have a very similar secondary structure. By performing site-specific mutagenesis studies, it was shown that one of the stem-and-loop structures could be deleted to half of its original size without affecting the catalytic activity. In addition, the other stem-and-loop contained a six base-pair helix, and the structure, rather than the sequence, of this helix was required for the catalytic activity. However, the structure of a portion of the stem-and-loop remains uncertain. We also report that this RNA can be divided into two separate molecules, which alone did not have cleavage activity but, when mixed, one of the RNAs could be cleaved in trans. This study thus reveals some features of the secondary structure of the HDV genomic RNA involved in self-catalyzed cleavage. A model of this RNA structure is presented.
J Mol Biol 1992 Jan 05
PMID:Sequence and structure of the catalytic RNA of hepatitis delta virus genomic RNA. 173 Oct 72

We report here on the genomic organization and expression of a nuclear gene coding for a plastid ribosomal protein. The gene encodes the plastid-specific ribosomal protein S22 (formerly named CS-S5). Southern blot analysis suggests that the gene is present in one copy in the spinach genome. The gene consists of 5 exons of sizes ranging from 108 to 273 bp and of 4 introns of 1410, 92, 386 and 82 bp. The exon-intron splice junctions and intron branch sites fit well the consensus sequences for plant introns. The major transcription start site has been determined 29 bp upstream of the AUG initiation codon by primer extension and S1 nuclease mapping. No canonical TATA box is found but some other possible promoter motifs are observed. Transcripts are detected in leaves, etiolated leaves, roots and seeds suggesting that the rps22 gene is expressed constitutively. During germination a marked increase in the relative steady-state level of the mRNA can be seen as soon as 24 h after imbibition of the seeds.
Plant Mol Biol 1992 Jan
PMID:Organization and expression of the nuclear gene coding for the plastid-specific S22 ribosomal protein from spinach. 173 92

We have characterized a series of rat genomic clones that code for the FSH receptor (FSHR) gene and approximately 14.8 kilobases of DNA up-stream of the transcriptional start sites. Southern blot analysis indicated that there was only a single gene for the FSHR. Primer extension and S1 nuclease experiments revealed the presence of two major transcriptional start sites at positions -80 and -98 relative to the translational start site. Transient expression studies of a fusion gene containing 830 basepairs of DNA 5' to the translational start site linked to the reporter gene chloramphenicol acyltransferase have shown that this portion of the gene is capable of acting as a transcriptional promoter in rat Sertoli cells. The FSHR gene contained 10 exons and nine introns. The first nine exons encoded the extensive amino-terminal domain of the receptor, while the last exon encoded the transmembrane-spanning and cytoplasmic domains. A repeated motif similar to that observed in the leucine-rich glycoprotein family was delineated within exons 2-9. Comparison of the FSHR gene to the LH receptor gene revealed a number of striking similarities which clearly indicate that these receptors evolved through gene duplication. The ancestral gene for these receptors presumably arose from a series of tandem duplications of the leucine-rich motif, which when combined with the common ancestral gene of the G-protein-coupled receptor family led to the current gene structure of the glycoprotein hormone receptors.
Mol Endocrinol 1992 Jan
PMID:Structural organization of the follicle-stimulating hormone receptor gene. 173 73

The termination of transcription in the dnaA gene of E. coli was analyzed using transcriptional fusions to the galactokinase gene, S1 nuclease mapping and quantification of translation products by Western blots. The majority of transcripts originating from dnaA promoters terminated at several positions within a 200 bp region inside the dnaA reading frame.
Mol Gen Genet 1991 Dec
PMID:Transcription termination in the dnaA gene. 176 43

Antigenic variation in the parasitic protozoan Giardia lamblia was studied by characterizing the expression and genomic organization of a variant-specific surface protein (VSP) gene. Transcripts from this gene, vsp1267, were abundant in the cloned variant WB/1267, but undetectable in the parental clone from which WB/1267 was derived or in variant progeny of WB/1267. Two identical copies of vsp1267 exist in the WB/1267 genome, separated by 3 kb and arranged as convergent transcription units. Primer extension sequencing and S1 nuclease protection analysis suggested that the 5' untranslated region (UTR) of VSP1267 mRNA consists of a single nucleotide (nt). Primer extension sequencing mapped the site of VSP1267 transcript polyadenylation 25 nt beyond the termination codon. vsp1267 contained no introns and predicted a cysteine-rich polypeptide with features common to other VSPs. Comparison of vsp1267 with another VSP gene sequence revealed striking conservation, both at the nucleotide and amino acid levels, and the 3' ends of the genes. An oligonucleotide derived from this region detected size-variant VSP transcripts in 4 of 5 G. lamblia clones analyzed, suggesting the general utility of this probe in studying VSP genes and their expression.
Mol Biochem Parasitol 1991 Dec
PMID:Carboxy-terminal sequence conservation among variant-specific surface proteins of Giardia lamblia. 177 65


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