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PubMed2003

Activation of influenza virus RNA polymerase by the 5' and 3' terminal duplex of genomic RNA.

The current model for influenza virus mRNA transcription involves the sequential interaction of the viral polymerase with the 5'- and 3'-ends of vRNA, with each RNA-protein interaction triggering a polymerase function necessary for cap-primed transcription. Here we show that the order in which this ternary complex is assembled is in fact important. Polymerase bound simultaneously to a pre-annealed duplex of the 5'- and 3'-ends of vRNA had greatly increased levels of primer binding and endonuclease activities compared to a sequentially assembled complex. Increased primer binding was due to the activation of a high affinity binding site with a preference for primer length RNAs. This correlated with enhanced levels of cap-primed transcription. Polymerase that was bound initially to just 5' vRNA had low primer binding activity, but was endonucleolytically active. Neither activity was significantly increased by the subsequent addition of 3' vRNA, and this sequentially assembled complex had correspondingly low mRNA transcription activity. Nevertheless, both routes of assembly led to complexes that were highly competent for dinucleotide ApG-primed transcription. Therefore, polymerase complexes assembled on pre-annealed 5' and 3' terminal viral RNA sequences have distinct properties from those assembled by sequential loading of polymerase onto the 5'-end followed by the 3'-end. This suggests a mechanism by which the virus couples transcription initiation and termination during mRNA transcription.

Endonucleases↗
PubMed1994

Human herpesvirus 6 infects cervical epithelial cells and transactivates human papillomavirus gene expression.

To examine whether human herpesvirus 6 (HHV-6) is capable of infecting human cervical epithelial cells and altering expression of human papillomavirus (HPV) genes, HPV-immortalized or -transformed carcinoma cell lines were infected with HHV-6 variant A. No cytopathic effect was observed in infected cervical cells. However, immunofluorescence indicated that infected cells expressed early-late proteins of HHV-6 by day 3 postinfection. HHV-6 DNA was also detected by Southern blot hybridization after infection and persisted through continued subculture in an episomal state as proven by Gardella gel electrophoresis and fluorescence in situ hybridization. HHV-6 infection enhanced expression of HPV RNAs encoding the viral oncoproteins E6 and E7. Transient transfection assays showed that two HHV-6 molecular clones, pZVB-70 and pZVH-14, upregulated transcription 9- to 15-fold from a receptor plasmid containing the HPV type 18 regulatory sequences which control transcription in vivo. Cervical carcinoma cells infected with HHV-6 induced more rapid development of tumors in mice than did noninfected cells. These results are the first evidence that human cervical epithelial cells can be infected with HHV-6 and that HHV-6 contains transactivators which stimulate the HPV-transforming genes.

Animals↗
PubMed1986

Morphological transformation of established rodent cell lines by high-level expression of the adenovirus type 2 E1a gene.

When a strong promoter derived from the mouse metallothionein gene was substituted for the homologous adenovirus type 2 E1a promoter, leading to enhanced levels of E1a RNAs and proteins in cells transfected with the chimeric gene, the E1a gene alone was able to induce in established cell lines alterations in cellular morphology and growth properties similar to those produced by the combined action of E1a and E1b genes. The qualitative effects of E1a gene expression upon cellular properties thus depend on the level of expression of the E1a gene. Furthermore, E1a may be the primary transforming gene of adenoviruses, since it produced many of the characteristics of transformed cells that had previously been attributed to E1b.

Adenovirus Early Proteins↗
PubMed1997

Functional activity and developmental regulation of DdRBP1, a RNA binding protein in Dictyostelium discoideum.

In an attempt to find potential components of natural antisense mechanisms in Dictyostelium, we investigated RNA binding protein (RBD) genes of the RNP-CS family. RBD proteins can enhance hybridization of complementary RNAs and may thus mediate the interaction of sense and antisense RNA. Using the conserved RNP1 and RNP2 motifs as primers, we cloned 4 PCR fragments containing ORFs and additional homologies to known members of the RNP-CS family. We cloned a full length cDNA for one protein (DdRBP1) that showed similarities to hnRNP A1. Recombinant protein synthesized in E. coli displayed binding to single stranded RNA and a weak annealing activity for partially complementary RNAs in vitro. Deletion of the RNP1 motif reduced RNA binding considerably but not completely. DdRBP1 is thus one of the few members of the RNP-CS family for which binding and annealing activities have been experimentally demonstrated. Polyclonal antisera directed against recombinant DdRBP1 detected a protein of approx. 40 kDa. In whole cell extracts, this protein was present in equal amounts throughout the developmental cycle of Dictyostelium while differential accumulation was observed in nuclei during early and late development.

Amino Acid Sequence↗
PubMed2003

[RNA responsible for conferring a DNase I sensitive structure on albumin gene in assembled chromatin].

Although the set of genes is virtually the same in all tissues,differential gene expression is appeared in cells of different kinds. Differentiation and ageing are associated with regulation of gene expression that is a fundamental mechanism in eukaryotic development and survival. The sensitivity to DNase I of actively transcribed genes seems to be a general phenomenon. The purpose of the study is to test whether RNAs obtained from different organs or cells can enhance susceptibility of albumin gene to DNase I digestion in BALB/c mouse brain chromatin assembled.RNAs extracted from rat liver, lung, kidney, brain, tRNA from yeast and synthesized RNAs (23 nt completed with mouse alb gene) were added to a system of chromatin reconstitution that was achieved by dialysis from high ionic strength solution. Assembled chromatin was digested with DNase I (12.5 microg/mL) at 20 degrees for 1 min, then PCR assay was used to detect the level of albumin gene digested. PCR products (1200 bp) were run on a 6% polyacylamide gel and analyzed by silver stain assay. RNAs from different organs and synthesized RNAs all increased the sensitivity of albumin gene to DNase I attack in mouse assembled chromatin. The effect was more obvious in liver and lung RNAs than in kidney and brain ones. tRNA from yeast did not enhance the sensitivity of albumin gene to DNase I digestion. RNA increased albumin gene sensitivity to DNase I in a dose-dependent manner. We report here for the first time that RNAs can enhance susceptibility of albumin gene to DNase I digestion. The effect is associated with RNA sources or sequences. It is generally agreed that the formation of gene sensitivity to DNase I, by unfolding of a tightly packed chromatin fiber, is the first step in gene activation, then RNAs that recognize complementary DNA sequences may be the specific factors that affect DNA supercoiling and determine the sensitivity of gene to DNase I digestion. Here we describes "RNA Population Gene Activating Model" that gives a logical interpretation of events leading to expression of specific genes during normal development and differentiation, in the same time,explains ageing and oncogenesis. Gene expression in eukaryotic cells requires two level regulations. The first may be controlled by RNAs that locate complementary regions within the genomes and make these regions loosened potentially, and the second is mainly involved in sequence specific and nonspecific proteins by which genomic regions bound by RNAs are unfolded. In eukaryotic cells, RNA fragments cleaved from all transcripts mix together to form "RNA populations" in which the majority is intron RNA. Every type of RNA fragments and its homologous sequences act as a group to form certain concentration in which repetitive sequences are more effective. If it is considered that there are many groups of RNA fragments in a particular cell,then different groups of RNA fragments are presented in dissimilar cell types of differentiation. Between DNA replication and nucleosome formation, RNA fragments in nuclear liquid will compete with DNA for binding to complement regions, then the chromatin regions bound to RNA can not be wrapped to form typical nucleosomes. After DNA doubles and is divided into 2 cells, these regions containing atypical nucleosomes become loose by function of non-histone. Transcriptionally active regions of chromatin are loose conformation but loosened regions are not always transcriptionally active. In every division, cells suffer in the described procedure that genes express RNAs, then RNAs recognize and imprint DNA. There are different RNA populations in different cells so that they imprint different genes, which is the primary mechanism by which same genes have expression distinctness. Since loosened genes are similar to bacterial operator system, factors in environment around cells play roles in inducing different gene expression to form different RNA population, which is the primary reason of cell differentiation. RNA population produced by certain impressions in genome can not imprint to form the same ones, otherwise immortal cells will be emerged, so that this program also controls ageing and oncogenesis.

English Abstract↗
PubMed1986

Regulation of ferritin synthesis in malignant and non-malignant lymphoid cells.

The different amounts of H-rich and L-rich isoferritins found in malignant and non malignant lymphoid cells are accompanied by proportional variations in the relative quantity of messenger RNAs for the H and L subunits of ferritin. The correlation between levels of messenger RNAs and proteins suggests that the amount of messenger RNA plays an important role in ferritin biosynthesis in these cells. The enhanced expression of ferritin messenger RNAs in some neoplastic cells is not caused by gross alterations in the structure of ferritin genes.

Biopsy↗
PubMed2005

Control of translation by the 5'- and 3'-terminal regions of the dengue virus genome.

The genomic RNAs of flaviviruses such as dengue virus (DEN) have a 5' m7GpppN cap like those of cellular mRNAs but lack a 3' poly(A) tail. We have studied the contributions to translational expression of 5'- and 3'-terminal regions of the DEN serotype 2 genome by using luciferase reporter mRNAs transfected into Vero cells. DCLD RNA contained the entire DEN 5' and 3' untranslated regions (UTRs), as well as the first 36 codons of the capsid coding region fused to the luciferase reporter gene. Capped DCLD RNA was as efficiently translated in Vero cells as capped GLGpA RNA, a reporter with UTRs from the highly expressed alpha-globin mRNA and a 72-residue poly(A) tail. Analogous reporter RNAs with regulatory sequences from West Nile and Sindbis viruses were also strongly expressed. Although capped DCLD RNA was expressed much more efficiently than its uncapped form, uncapped DCLD RNA was translated 6 to 12 times more efficiently than uncapped RNAs with UTRs from globin mRNA. The 5' cap and DEN 3' UTR were the main sources of the translational efficiency of DCLD RNA, and they acted synergistically in enhancing translation. The DEN 3' UTR increased mRNA stability, although this effect was considerably weaker than the enhancement of translational efficiency. The DEN 3' UTR thus has translational regulatory properties similar to those of a poly(A) tail. Its translation-enhancing effect was observed for RNAs with globin or DEN 5' sequences, indicating no codependency between viral 5' and 3' sequences. Deletion studies showed that translational enhancement provided by the DEN 3' UTR is attributable to the cumulative contributions of several conserved elements, as well as a nonconserved domain adjacent to the stop codon. One of the conserved elements was the conserved sequence (CS) CS1 that is complementary to cCS1 present in the 5' end of the DEN polyprotein open reading frame. Complementarity between CS1 and cCS1 was not required for efficient translation.

3' Untranslated Regions↗
PubMed1987

Characterisation of the 5'-leader sequence of tobacco mosaic virus RNA as a general enhancer of translation in vitro.

Uncapped messenger RNAs (mRNAs) encoding calf preprochymosin, chicken prelysozyme, or Escherichia coli beta-glucuronidase (GUS) were synthesized in vitro, with or without a 5'-terminal 67-nucleotide sequence (omega') derived from the untranslated 5'-leader (omega) of tobacco mosaic virus (TMV) RNA. Messenger RNAs were translated in vitro, in messenger-dependent systems derived from rabbit reticulocytes (MDL), wheat-germ (WG) or E. coli (EC). The omega' sequence enhanced expression of each mRNA in almost every translation system. While MDL was the least responsive to omega', this sequence proved particularly efficient in permitting translation of the eukaryotic mRNAs in EC, despite the absence of a consensus Shine-Dalgarno sequence in either the mRNAs or omega'. The local context of the initiation codon (AUG) in two GUS mRNA constructs did not influence the relative enhancement caused by the omega' sequence. These findings extend the utility of omega' as a general enhancer of translation for both prokaryotic and eukaryotic mRNAs in either 80S- or 70S-ribosome-based systems.

Acetyltransferases↗
PubMed2006

Assessing IRES activity in the HIF-1alpha and other cellular 5' UTRs.

Dicistronic reporter plasmids, such as the dual luciferase-containing pR-F plasmid, have been widely used to assay cellular and viral 5' untranslated regions (UTRs) for IRES activity. We found that the pR-F dicistronic reporter containing the 5' UTRs from HIF-1alpha, VEGF, c-myc, XIAP, VEGFR-1, or Egr-1 UTRs all produce the downstream luciferase predominantly as a result of cryptic promoter activity that is activated by the SV40 enhancer elements in the plasmid. RNA transfection experiments using dicistronic or uncapped RNAs, which avoid the complication of cryptic promoter activity, indicate that the HIF-1alpha, VEGF, c-myc, and XIAP UTRs do have some IRES activity, although the activity was much less than that of the viral EMCV IRES. The translation of transfected monocistronic RNAs containing these cellular UTRs was greatly enhanced by the presence of a 5' cap, raising questions as to the strength or mechanism of IRES-mediated translation in these assays.

5' Untranslated Regions↗
PubMed1985

Rearrangements in the long terminal repeat of extra mouse mammary tumor proviruses in T-cell leukemias of mouse strain GR result in a novel enhancer-like structure.

Male GR mice develop T-cell leukemia at low frequency late in life. These leukemia cells invariably contain large amounts of mouse mammary tumor virus (MMTV) RNA and MMTV proteins and have extra MMTV proviruses integrated in their DNA. We show here that the extra MMTV proviruses are all derived from the endogenous MMTV provirus associated with the Mtv-2 locus and that the T-cell leukemias are clonal with respect to the acquired MMTV proviruses. The extra MMTV proviruses in six transplantable T-cell leukemia lines studied had rearranged, shortened long terminal repeats (LTRs); each T-cell leukemia, however, had a different LTR rearrangement within its extra MMTV provirus. The alteration within the extra LTRs of T-cell leukemia line 42 involved deletion of 453 nucleotides and generation of a tandem repeat region consisting of regions flanking the deletion. This alteration generated a sequence similar to the adenovirus enhancer core sequence. The viral RNAs in the T-cell leukemias contained corresponding alterations in their U3 regions. These results demonstrate that expression of MMTV in T-cell leukemias of GR mice may be the consequence of the generation of a novel enhancer, which could also stimulate expression of any adjacent cellular oncogene.

Animals↗
PubMed2000

Induction of cytidine to uridine editing on cytoplasmic apolipoprotein B mRNA by overexpressing APOBEC-1.

Post-transcriptional editing of apolipoprotein B (apoB) mRNA is regulated in hepatic cells to achieve a steady state proportion of edited and unedited RNA molecules. This activity is catalyzed by APOBEC-1 (apoB mRNA editing catalytic subunit 1) in what has been widely accepted as nuclear event occurring during or after mRNA splicing. Introns impair the efficiency of editing within an adjacent exon in a distance-dependent manner in reporter RNAs. We show here that this inhibition can be overcome by overexpressing APOBEC-1 and that the enhanced editing efficiency on these reporter RNAs occurred after splicing on cytoplasmic transcripts. Given the absolute requirement of auxiliary proteins in apoB mRNA editing, the data suggested that auxiliary proteins were distributed with APOBEC-1 in both the nucleus and cytoplasm of McArdle cells. In fact, immunolocalization of one such auxiliary protein, APOBEC-1 complementation factor (ACF) demonstrated a nuclear and cytoplasmic distribution. We also demonstrate that in the absence of alterations in APOBEC-1 expression, changes in edited apoB RNA induced by ethanol arise through the stimulation of nuclear editing activity. The finding that apoB mRNA editing can occur in the cytoplasm but normally does not suggests that under biological conditions, restricting editing activity to the nucleus must be an important step in regulating the proportion of the edited apoB mRNAs.

APOBEC-1 Deaminase↗
PubMed1989

Phenobarbital-inducible gene expression in developing rat liver: relationship to hepatocyte function.

The expression of phenobarbital-, pregnenolone 16 alpha-carbonitrile- and polycyclic aromatic hydrocarbon-inducible cytochromes P-450 and of phenobarbital-inducible UDP-glucuronosyltransferase was examined in developing rat liver. RNAs coding for these proteins were present in fetal rat liver and their respective concentrations remained quite stable in non-induced animals. Inducers differently affected the concentration of RNAs: clofibrate had no action, whereas methylcholanthrene was highly active in fetal liver. Induction by phenobarbital gradually increased during ontogenesis, in parallel with the augmentation of the number of hepatocyte cells in the liver. Our contribution definitively demonstrates that the ability of phenobarbital to enhance P-450 and UDPGT RNAs is strictly restricted to hepatocytes and remains roughly unchanged throughout ontogenesis. In addition, phenobarbital was also able to potentiate the inducing capacity of methylcholanthrene (i.e., raising the TCDD-binding protein) exclusively in hepatocytes. This is the first direct evidence that the number of hepatocytes in the liver, rather than a biochemical maturation, controls the expression of phenobarbital-inducible genes. Pregnenolone 16 alpha-carbonitrile was also effective as inducer in fetal and neonatal rats and its maximal effect was observed in 5-d-old neonates, suggesting a regulation mechanism temporally different from that of phenobarbital.

Animals↗
PubMed1991

Expression of hematopoietic growth factor RNAs in human mesenchymal cells from various organs.

Experiments were undertaken to study expression of hematopoietic growth factor RNAs in mesenchymal cells from a variety of organs including bone marrow, foreskin, gingiva, and lung. Cells from each organ had negligible expression of RNAs coding for granulocyte (G), macrophage (M), and granulocyte-macrophage (GM) colony stimulating factor (CSF), interleukin 1 beta (IL-1 beta), and IL-6. Fibroblasts from each tissue had a comparable ability to express the same cytokine RNAs. Surprisingly, the stimuli for expression of G-CSF RNA was disparate from the stimuli for expression of the other cytokine RNAs. While IL-1 beta enhanced accumulation of G-CSF RNA, tumor necrosis factor alpha (TNF) and 12-O-tetradecanoylphorbol-13-acetate (TPA) did not. In contrast, IL-1 beta, TNF, and TPA equally stimulated increased levels of M-CSF, GM-CSF, IL-1 beta and IL-6 RNAs.

Bone Marrow↗
PubMed1997

Identification of a new class of exonic splicing enhancers by in vivo selection.

In vitro selection strategies have typically been used to identify a preferred ligand, usually an RNA, for an identified protein. Ideally, one would like to know RNA consensus sequences preferred in vivo for as-yet-unidentified factors. The ability to select RNA-processing signals would be particularly beneficial in the analysis of exon enhancer sequences that function in exon recognition during pre-mRNA splicing. Exon enhancers represent a class of potentially ubiquitous RNA-processing signals whose actual prevalence is unknown. To establish an approach for in vivo selection, we developed an iterative scheme to select for exon sequences that enhance exon inclusion. This approach is modeled on the in vitro SELEX procedure and uses transient transfection in an iterative procedure to enrich RNA-processing signals in cultured vertebrate cells. Two predominant sequence motifs were enriched after three rounds of selection: a purine-rich motif that resembles previously identified splicing enhancers and a class of A/C-rich splicing enhancers (ACEs). Individual selected ACEs enhanced splicing in vivo and in vitro. ACE splicing activity was competed by RNAs containing the purine-rich splicing enhancer from cardiac troponin T exon 5. Thus, ACE activity is likely to require a subset of the SR splicing factors previously shown to mediate activity of this purine-rich enhancer. ACE motifs are found in two vertebrate exons previously demonstrated to contain splicing enhancer activity as well as in the well-characterized Drosophila doublesex (dsx) splicing enhancer. We demonstrate that one copy of the dsx repeat enhances splicing of a vertebrate exon in vertebrate cells and that this enhancer activity requires the ACE motif. We suggest the possibility that the dsx enhancer is a member of a previously unrecognized family of ACEs.

Animals↗
PubMed2003

Direct repression of splicing by transformer-2.

The Drosophila melanogaster sex determination factor Tra2 positively regulates the splicing of both doublesex (dsx) and fruitless (fru) pre-mRNAs but negatively affects the splicing of the M1 intron in tra2 pre-mRNA. Retention of the M1 intron is known to be part of a negative-feedback mechanism wherein the Tra2 protein limits its own synthesis, but the mechanism responsible for accumulation of M1-containing RNA is unknown. Here we show that the recombinant Tra2 protein specifically represses M1 splicing in Drosophila nuclear extracts. We find that the Tra2 protein binds directly to several sites in and near the M1 intron and that, when Tra2 binding is competed with other RNAs, the splicing of M1 is restored. Mapping the RNA sequences functionally required for M1 repression identified both a 34-nucleotide (nt) A/C-rich sequence immediately upstream of the M1 5' splice site and a region within the intron itself. The AC-rich sequence is largely composed of a repeated 4-nt sequence that also forms a subrepeat within the repeated 13-nt splicing enhancer elements of fru and dsx RNAs. Although required for repression, the element also enhances M1 splicing in the absence of Tra2. We propose that Tra2 represses M1 splicing by interacting with multiple sequences in the pre-mRNA and interfering with enhancer function.

Alternative Splicing↗
PubMed2003

The effects of pre-B-cell colony-enhancing factor on the human fetal membranes by microarray analysis.

OBJECTIVE: Our purpose was to show the effects of pre-B-cell colony-enhancing factor on the genes that are expressed by the human fetal membranes. STUDY DESIGN: Explants of fetal membranes (amnion, chorion, and decidua) from three term patients were treated with 100 ng/mL recombinant human pre-B-cell colony-enhancing factor for 4 hours. RNAs were hybridized to gene chips that contained >18,000 known genes. One experiment was done in triplicate to assess replication. Data were analyzed to quantitate the signal intensities of each complementary DNA on the array. Confirmation of the results was carried out on tissues from nine other patients by the measurement of the proteins or quantitative real-time reverse transcriptase-polymerase chain reaction. RESULTS: Replication gave <92.6% identical results, which showed high method reproducibility. Pre-B-cell colony-enhancing factor treatment caused a significant increase in 103 genes and decrease in 139 genes. Only 8 genes were up-regulated consistently and significantly in all three patients (three key inflammatory cytokines [tumor necrosis factor-alpha, interleukin-6, and interleukin-1beta], four important chemokines [macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, macrophage inflammatory protein-3alpha, and growth-related oncogene-gamma], and prostaglandin-endoperoxide synthase 2). These data were confirmed by the measurement in the media with the use of specific enzyme-linked immunosorbent assays for tumor necrosis factor-alpha, interleukin-6, and interleukin-1beta, macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, and macrophage inflammatory protein-3alpha and by quantitative real-time reverse transcriptase-polymerase chain reaction for growth-related oncogene-gamma and prostaglandin-endoperoxide synthase 2. CONCLUSION: Pre-B-cell colony-enhancing factor appears to be at the proximal end of the pathway to labor initiation and may link sterile distention-induced labor with that of infection-induced labor.

Amnion↗
PubMed1987

Morpholino spin-labeling for base-pair sequencing of a 3'-terminal RNA stem by proton homonuclear Overhauser enhancements: yeast ribosomal 5S RNA.

Base-pair sequences for 5S and 5.8S RNAs are not readily extracted from proton homonuclear nuclear Overhauser enhancement (NOE) connectivity experiments alone, due to extensive peak overlap in the downfield (11-15 ppm) proton NMR spectrum. In this paper, we introduce a new method for base-pair proton peak assignment for ribosomal RNAs, based upon the distance-dependent broadening of the resonances of base-pair protons spatially proximal to a paramagnetic group. Introduction of a nitroxide spin-label covalently attached to the 3'-terminal ribose provides an unequivocal starting point for base-pair hydrogen-bond proton NMR assignment. Subsequent NOE connectivities then establish the base-pair sequence for the terminal stem of a 5S RNA. Periodate oxidation of yeast 5S RNA, followed by reaction with 4-amino-2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO-NH2) and sodium borohydride reduction, produces yeast 5S RNA specifically labeled with a paramagnetic nitroxide group at the 3'-terminal ribose. Comparison of the 500-MHz 1H NMR spectra of native and 3'-terminal spin-labeled yeast 5S RNA serves to identify the terminal base pair (G1 . C120) and its adjacent base pair (G2 . U119) on the basis of their proximity to the 3'-terminal spin-label. From that starting point, we have then identified (G . C, A . U, or G . U) and sequenced eight of the nine base pairs in the terminal helix via primary and secondary NOE's.

Base Composition↗
PubMed1996

Antisense ribosomes: rRNA as a vehicle for antisense RNAs.

Although rRNA has a conserved core structure, its size varies by more than 2000 bases between eubacteria and vertebrates, mostly due to the size variation of discrete variable regions. Previous studies have shown that insertion of foreign sequences into some of these variable regions has little effect on rRNA function. These properties make rRNA a potentially very advantageous vehicle to carry other RNA moieties with biological activity, such as "antisense RNAs." We have explored this possibility by inserting antisense RNAs targeted against one essential and two nonessential genes into a site within a variable region in the Tetrahymena thermophila large subunit rRNA gene. Expression of each of the three genes tested can be drastically reduced or eliminated in transformed T. thermophila lines containing these altered rRNAs. In addition, we found that only antisense rRNAs containing RNA sequences complementary to the 5' untranslated region of the targeted mRNA were effective. Lines containing antisense rRNAs targeted against either of the nonessential genes grow well, indicating that the altered rRNAs fulfill their functions within the ribosome. Since functional rRNA is extremely abundant and stable and comes into direct contact with translated mRNAs, it may prove to be an unparalleled vehicle for enhancing the activity of functional RNAs that act on mRNAs.

Bacterial Proteins↗