Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When E. coli protein synthesis was blocked by chloramphenicol (100 micrograms/ml) or by essential amino acid deprivation, the transcription rates of rplKAJL genes (the ones for L11, L4, L10 and L7/L12 ribosomal proteins) and adjacent rpoBC genes (genes for RNA polymerase beta- and beta'-polypeptides) have been non-coordinately changed. The level of the gene transcription rate was obtained from RNA--DNA hybridization assays with E. coli pulse-labelled RNA and pJC703 or pJC720 plasmid DNA. The transcription of ribosomal protein genes has been found to be uncoupled with translation and controlled by the allelic state of relA gene. Conversely, the effective transcription of proBC gene was relA independent and coupled with translation of the mRNA. Chloramphenicol-induced transcription polarity within rplKAJL-rpoBC chromosome region can be suppressed by 10 micrograms/ml rifampicin.
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PMID:[Non-coordinated transcription of RNA polymerase beta,beta'-polypeptide genes and adjacent ribosomal protein genes in Escherichia coli cells]. 701 82

The gene encoding the beta subunit of Bacillus subtilis RNA polymerase was isolated from a lambda gt11 expression library using an antibody probe. Gene identity was confirmed by the similarity of its predicted product to the Escherichia coli beta subunit and by mapping an alteration conferring rifampicin resistance within the conserved rif coding region. Including the rif region, four colinear blocks of sequence similarity were shared between the B. subtilis and E. coli beta subunits. In E. coli, these conserved blocks are separated by three regions that either were not conserved or were entirely absent from the B. subtilis protein. The B. subtilis beta gene was part of a cluster with the order rplL (encoding ribosomal protein L7/L12), orf23 (encoding a 22,513-dalton protein that is apparently essential for growth), rpoB (beta), and rpoC (beta'). This organization differs from the corresponding region in E. coli by the inclusion of orf23. Experiments using promoter probe vectors and site-directed mutagenesis located a major rpoB promoter overlapping the 3'-coding region of orf23, 250 nucleotides upstream from the beta initiation codon. Thus, the B. subtilis rpoB region differs from its E. coli counterpart in both genetic and transcriptional organization.
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PMID:Genetic and transcriptional organization of the region encoding the beta subunit of Bacillus subtilis RNA polymerase. 765 5

A conserved architectural feature of ribosomes is a protuberance (the stalk) in the large subunit, essential for ribosomal interactions with translational factors and GTP hydrolysis and generated by two dimers of L12, the only multicopy protein in ribosomes. In higher plants, the rpl12 gene for chloroplast L12 is located in the nucleus. We report here the cloning and sequencing of this nuclear gene from Arabidopsis thaliana, revealing the first gene family for a chloroplast ribosomal protein (RP). A single cluster/haploid genome of three rpl12 genes is located in the sequenced 9.1-kilobase region of the Arabidopsis genome. Two of the rpl12 genes encode identical mature proteins, and the third encodes a 25% divergent RP, although the chloroplast-targeting transit peptide in each is distinct. The rpl12 genes encoding identical RPs are closely linked at their 5' ends to identical cytosolic tRNA(Pro) genes with a < 250-base pair spacer. Reverse transcriptase polymerase chain reaction experiments with total RNA isolated from Arabidopsis (and characterization of several L12 cDNA clones) show that only the tRNA-linked rpl12 genes are expressed. We also show (by polymerase chain reaction experiments with isolated total DNA) that this tRNA(Pro)-rpl12 gene linkage is conserved in spinach (inferred to contain a single gene copy) indicating its importance. The previously described enhanced translation of spinach L12 mRNA from its two tandem AUG codons and the two functional rpl12 genes in Arabidopsis probably provide two mechanisms for generating the four copies of L12/chloroplast ribosome, qualitatively different from those attempted in eubacteria.
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PMID:Multicopy GTPase center protein L12 of Arabidopsis chloroplast ribosome is encoded by a clustered nuclear gene family with the expressed members closely linked to tRNA(Pro) genes. 812 49

A 6.5-kb DNA fragment containing the gene (rpoB) encoding the RNA polymerase (RNAP) beta subunit, from the mollicute Spiroplasma citri (Sc), was cloned and sequenced. The classical eubacterial organization, with the genes (rplK, A, J and L) encoding ribosomal proteins L11, L1, L10 and L12 located immediately upstream from rpoB, was not found in the Sc DNA. Instead, an open reading frame (hsdS) potentially encoding a component of a type I restriction and modification system was identified upstream from rpoB, and sequences showing similarities with insertion elements were found between hsdS and rpoB.
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PMID:The unique organization of the rpoB region of Spiroplasma citri: a restriction and modification system gene is adjacent to rpoB. 867 39

Western blots of two-dimensional electrophoretic maps of proteins from Chlamydia trachomatis were probed with sera from 17 seropositive patients with genital inflammatory disease. Immunoblot patterns (comprising 28 to 2 spots, average 14.8) were different for each patient; however, antibodies against a spot-cluster due to the chlamydia-specific antigen outer membrane protein-2 (OMP2) were observed in all sera. The next most frequent group of antibodies (15/17; 88%) recognized the hsp60 GroEL-like protein, described as immunopathogenic in chlamydial infections. Reactivity to the major surface-exposed and variable antigen major outer membrane protein (MOMP) was observed at a relatively lower frequency (13/17; 76%). The hsp70 DnaK-like protein was also frequently recognized (11/17; 64.7%) in this patient group. Besides the above confirmatory findings, the study detected several new immunoreactive proteins, with frequencies ranging from 11/17 to 1/17. Some were characterized also by N-terminal amino acid sequencing and homology searches. Amongst these were a novel outer membrane protein (OmpB) and, interestingly, five conserved bacterial proteins: four (23%) sera reacted with the RNA polymerase alpha-subunit, five (29%) recognized the ribosomal protein S1, eight (47%) the protein elongation factor EF-Tu, seven (41%) a putative stress-induced protease of the HtrA family, and seven sera (41%) the ribosomal protein L7/L12. Homologs of the last two proteins were shown to confer protective immunity in other bacterial infections. The data show that immunological sensitization processes commonly thought to play a role in chlamydial pathogenicity may be sustained not only by the hsp60 GroEl-like protein, but also by other conserved bacterial antigens, some of which may be also considered as potential vaccine candidates.
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PMID:Identification of immunoreactive proteins of Chlamydia trachomatis by Western blot analysis of a two-dimensional electrophoresis map with patient sera. 1049 31

The DNA-binding protein GerE acts as both a repressor and an activator of transcription of genes transcribed by sigma(K)-RNA polymerase (RNA-P) during the later stages of endospore formation in Bacillus subtilis. GerE represses transcription from the sigK promoter, and activates transcription from other promoters, including cotC and cotX. Two different regions of GerE (AR1 and AR2) are required for activation of cotC and cotX, respectively. We used a genetic screen to seek mutations that would define additional regions of GerE required for promoter activation. We found that a substitution of proline for leucine at position 12 of GerE (L12P) decreased cotC promoter activity but did not interfere with GerE-dependent repression of the sigK promoter or with activation of the cotX promoter in vivo. We also found that the L12P substitution had no effect on binding to cotC in vitro. However, the L12P-substituted GerE failed to stimulate cotC transcription in vitro, whereas it stimulated transcription from PcotX. The crystal structure of GerE suggests that L12 is not exposed on the surface of the molecule. Therefore, we propose that the L12P substitution reduces the flexibility of the N-terminal arm, preventing an interaction of AR1 with RNA-P that is essential for activation of the cotC promoter.
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PMID:A mutation in GerE that affects cotC promoter activation in Bacillus subtilis. 1203 81

Most Sinorhizobium meliloti strains lack several key genes involved in microbial biotin biosynthesis, and it is assumed that this may be a special adaptation which allows the microbe to down-regulate metabolic activities in the absence of a host plant. To further explore this hypothesis, we employed two different strategies. (i) Searches of the S. meliloti genome database in combination with the construction of nine different gusA reporter fusions identified three genes involved in a biotin starvation response in this microbe. A gene coding for a protein-methyl carboxyl transferase (pcm) exhibited 13.6-fold-higher transcription under biotin-limiting conditions than cells grown in the presence of 40 nM biotin. Consistent with this observation, biotin-limiting conditions resulted in a significantly decreased survival of pcm mutant cells compared to parental cells or cells grown in the presence of 40 nM biotin. Further studies indicated that the autoinducer synthase gene, sinI, was transcribed at a 4.5-fold-higher level in early stationary phase in biotin-starved cells than in biotin-supplemented cells. Lastly, we observed that open reading frame smc02283, which codes for a putative copper resistance protein (CopC), was 21-fold down-regulated in response to biotin starvation. (ii) In a second approach, proteome analysis identified 10 proteins which were significantly down-regulated under the biotin-limiting conditions. Among the proteins identified by using matrix-assisted laser desorption ionization-time of flight mass spectrometry were the pi subunit of the RNA polymerase and the 50S ribosomal protein L7/L12 (L8) subunit, indicating that biotin-limiting conditions generally affect transcription and translation in S. meliloti.
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PMID:Biotin limitation in Sinorhizobium meliloti strain 1021 alters transcription and translation. 1257 Oct 48


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