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)

RNA polymerase (RNAP) moves along DNA while carrying out transcription, acting as a molecular motor. Transcriptional velocities for single molecules of Escherichia coli RNAP were measured as progressively larger forces were applied by a feedback-controlled optical trap. The shapes of RNAP force-velocity curves are distinct from those of the motor enzymes myosin or kinesin, and indicate that biochemical steps limiting transcription rates at low loads do not generate movement. Modeling the data suggests that high loads may halt RNAP by promoting a structural change which moves all or part of the enzyme backwards through a comparatively large distance, corresponding to 5 to 10 base pairs. This contrasts with previous models that assumed force acts directly upon a single-base translocation step.
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PMID:Force and velocity measured for single molecules of RNA polymerase. 979 53

The rates of transcription of several protein coding genes during Acanthamoeba differentiation have been examined by nuclear run-on and RNase protection assays. During early encystment, transcription by RNA polymerase II increases approximately 4-fold, whereas transcription by RNA polymerases I and III is decreased, as previously described. The rates of transcription from a wide variety of individual genes are only slightly affected during the first 16 h of encystment, although profilin gene expression is markedly increased. The levels of mRNAs encoding TPBF, TATA binding protein, cyclin-dependent kinase, protein disulfide isomerase, profilin, myosin II heavy chain, ubiquitin and extendin are stable during mature cyst formation, whereas mRNAs encoding actin, S-adenosyl methionine synthase and tubulin are substantially decreased in abundance within 16 h of starvation-induced encystment. We conclude that in contrast to the negative regulation of large rRNA and 5S rRNA synthesis during differentiation, the RNA polymerase II transcription apparatus is not negatively regulated. Control of Acanthamoeba differentiation is likely to be mediated by positive regulation of genes necessary for cyst maturation.
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PMID:Transcription by RNA polymerase II during Acanthamoeba differentiation. 987 98

The mechanical manipulation of single biological molecules is stimulating new and exciting research in many fields of study, including molecular motor mechanics, biopolymer properties, protein unfolding, receptor-ligand interactions, and more. Some recent highlights include the elucidation of the coupling ratios of myosin and kinesin, the demonstration of oscillatory forces in dynein arms, the determination of the force-velocity relation of RNA polymerase, and the direct mechanical observation of unfolding of single domains of titin and tenascin.
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PMID:Manipulation of single molecules in biology. 1004 11

We report the identification and cloning of a unique chick myosin heavy chain (CMHC1) that is expressed exclusively in the heart during embryogenesis. Using primers specific to myosin heavy chains, we used reverse transcriptase-polymerase chain reaction to clone and isolate CMHC1 from embryonic day 10 chicken heart RNA. Sequence analysis indicated that CMHC1 was a novel member of the myosin heavy chain family. Expression of the CMHC1 transcripts was detected in Hamburger Hamilton stage 10 chick embryos in the fusing myocardium. Expression of CMHC1 was maintained at high levels throughout the tubular heart of later stage embryos. Reverse transcriptase-polymerase chain reaction and in situ hybridizations failed to detect CMHC1 transcripts in the developing somites, limb buds, or skeletal musculature at any stage of chick development. Genomic CMHC1 clones have been isolated that contain sequences approximately 5.2 kilobase upstream of the presumptive CMHC1 transcription start site. Portions of the upstream regulatory region induced a 21-fold increase in reporter gene expression in primary cardiomyocytes. Because of its unique cardiac-restricted expression, CMHC1 will provide an excellent model system to study the molecular mechanisms required for the early developmental regulation of heart-specific genes.
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PMID:Identification and genomic cloning of CMHC1. A unique myosin heavy chain expressed exclusively in the developing chicken heart. 1063 96

Helical filaments driven by linear molecular motors are anticipated to rotate around their axis, but rotation consistent with the helical pitch has not been observed. 14S dynein and non-claret disjunctional protein (ncd) rotated a microtubule more efficiently than expected for its helical pitch, and myosin rotated an actin filament only poorly. For DNA-based motors such as RNA polymerase, transcription-induced supercoiling of DNA supports the general picture of tracking along the DNA helix. Here we report direct and real-time optical microscopy measurements of rotation rate that are consistent with high-fidelity tracking. Single RNA polymerase molecules attached to a glass surface rotated DNA for >100 revolutions around the right-handed screw axis of the double helix with a rotary torque of >5 pN nm. This real-time observation of rotation opens the possibility of resolving individual transcription steps.
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PMID:Direct observation of DNA rotation during transcription by Escherichia coli RNA polymerase. 1134 25

Animal- and human-made motors vary widely in size and shape, are constructed of vastly different materials, use different mechanisms, and produce an enormous range of mass-specific power. Despite these differences, there is remarkable consistency in the maximum net force produced by broad classes of animal- and human-made motors. Motors that use force production to accomplish steady translational motion of a load (myosin, kinesin, dynein, and RNA polymerase molecules, muscle cells, whole muscles, winches, linear actuators, and rockets) have maximal force outputs that scale as the two-thirds power of mass, i.e., with cross-sectional area. Motors that use cyclical motion to generate force and are more subject to multiaxial stress and vibration have maximal force outputs that scale as a single isometric function of motor mass with mass-specific net force output averaging 57 N x kg(-1) (SD = 14). Examples of this class of motors includes flying birds, bats, and insects, swimming fish, various taxa of running animals, piston engines, electric motors, and all types of jets. Dependence of force production and stress resistance on cross-sectional area is well known, but the isometric scaling and common upper limit of mass-specific force production by cyclical motion motors has not been recognized previously and is not explained by an existing body of theory. Remarkably, this finding indicates that most of the motors used by humans and animals for transportation have a common upper limit of mass-specific net force output that is independent of materials and mechanisms.
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PMID:Molecules, muscles, and machines: universal performance characteristics of motors. 1191 97

Genetic responses that characterize experimental autoimmune myocarditis (EAM) have not yet been determined. To investigate gene expression in the myocardium of EAM, absolute copy numbers of 44 mRNA species [calcium-handling proteins, contractile proteins, natriuretic peptides (NPs), cytokines, chemokines, growth factors, renin-angiotensin-aldosterone (RAA) system, endothelins (ETs) and extracellular matrix] in synthesized cDNA from a fixed quantity of total heart RNA were assessed using real-time reverse-transcriptase PCR at days 0, 14, 21 and 28 after immunization. alpha-Cardiac myosin showed a 26.3-fold decrease and beta-cardiac myosin a 3.75-fold increase at day 14. Atrial NP and brain NP increased 47.7- and 6.35-fold at days 21 and 14 respectively. Angiotensin II type 1 receptor, angiotensin-converting enzyme and ET1 increased 22.3-fold at day 21, 6.30-fold at day 21 and 16.8-fold at day 14 respectively. Aldosterone receptor decreased 2.15-fold at day 14, but aldosterone synthetase was detected only at days 14 and 21. Interleukin (IL)-2, IL-10, interferon-gamma and monocyte chemo-attractant protein-1 increased 9.08-fold at day 14, 398-fold at day 21, 43.1-fold at day 14 and 142-fold at day 14 respectively. Collagen type 3, collagen type 1 and fibronectin increased 34.6-, 1.74- and 44.4-fold respectively at day 21. Interestingly, osteopontin showed a 4540-fold increase and it was the highest mRNA of all at day 14. An isoform of cardiac myosin and NP are dramatically changed in EAM. RAA system and ET expressions are changed differently during the EAM time course. Cytokine, chemokine and extracellular matrix greatly increase and, in particular, large numbers of osteopontin mRNA are expressed in early EAM.
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PMID:Time course of gene expression in rat experimental autoimmune myocarditis. 1244 15

Satellite cells were isolated from biopsies of the biceps femoris of adult dogs. Virtually all cells expressed muscle-specific proteins. Proliferation of satellite cells increased as the concentration of fetal calf serum (FCS) was increased from 1 to 10% of the basal medium. The addition of mitogenic growth factors resulted in greater proliferation than that of cells cultured in basal medium alone. Maximum proliferation was obtained when fibroblast growth factor-basic (FGF2) was added to the medium, but differences existed between sources or types. Proliferation did not plateau when the concentration of recombinant human FGF2 was 75 ng/ml but reached maximum levels when 50 ng/ml of bovine FGF2 or 10 ng/ml of growth hormone or insulin-like growth factor-1 were added to the medium. Proliferation of satellite cells decreased when more than 5 ng/ml of transforming growth factor-alpha was included in the medium. Exposure of canine satellite cells to chemically defined media induced greater fusion of total nuclei (ODM-34%; 4F, ITT-CF, and SFG-23%) than exposure to other treatments, such as basal medium plus 2 mg/ml of 1-beta-d-arabinofuranosylcytosine, 5% chick embryo extract, 1% horse serum (average 9% fused nuclei), or 1% FCS (2% fused nuclei). Actin, myosin, desmin, neural cell adhesion molecule, MyoD1, and myogenin were expressed by canine satellite cells, but expression of major histocompatibility complex class II antigen was not detected. Reverse transcriptase-polymerase chain reaction detected expression of messenger ribonucleic acid for interleukin-6 (IL-6), IL-15, and leukemia inhibitory factor by canine satellite cells. Collectively, these data suggest that isolated canine satellite cells display properties of other types of myogenic cells and may be useful for further study of the regulation of postnatal myogenesis.
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PMID:Isolation and characterization of canine satellite cells. 1260 41

A common feature in the maturation of linear dsDNA viruses is that the lengthy viral genome is translocated with remarkable velocity into a limited space within a preformed protein shell using ATP as motor energy. Most biomotors, such as myosin, kinesin, DNA-helicase, and RNA polymerase, contain one ATP-binding component that acts processively. An examination of the well-studied dsDNA viruses reveals that DNA packaging motors involve two nonstructural components. Which component of the motor is the integrated processive factor to turn the motor has not been identified. In bacterial virus phi 29, these two components consist of a gp16 protein and an RNA molecule called pRNA. We have previously predicted and recently confirmed that gp16 binds ATP. It is generally believed that gp16 serves as an ATP-binding and processive component to drive the motor. In this article, phi 29 DNA-packaging intermediates were purified in quantity and examined to differentiate the role between gp16 and pRNA. It was found that the pRNA hexamer is an integral motor component, while gp16 is not stably bound. Only one pRNA hexamer, but multiple copies of gp16, were needed to accomplish DNA packaging. pRNA functions continuously during the entire DNA translocation process, suggesting that pRNA is a vital part of the DNA packaging motor.
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PMID:Only one pRNA hexamer but multiple copies of the DNA-packaging protein gp16 are needed for the motor to package bacterial virus phi29 genomic DNA. 1272 31

Two smooth muscle myosin heavy chain isoforms that differ by the presence ([+]insert) or the absence ([-]insert) of a 7-amino acid insert in the motor domain have a 2-fold difference in their in vitro actin filament velocity. We hypothesized that a preferential expression of the fast (+)insert isoform in airway smooth muscle would increase the rate of bronchoconstriction. To verify our hypothesis we measured the time course of bronchoconstriction following a bolus injection of methacholine (160 microg/kg) in (+)insert isoform knockout (KO) and corresponding wild-type (WT) mice. Neither baseline airway resistance (Raw) (0.424 +/- 0.04 for WT and 0.374 +/- 0.01 cm H(2)O.s.ml(-1) for KO) nor peak Raw (4.1 +/- 0.9 for WT and 4.0 +/- 0.5 cm H(2)O.s.ml(-1) for KO) differed between groups. However, the time to peak Raw was significantly longer in the KO (17.2 +/- 0.6 s) compared with the WT (14.6 +/- 0.8 s) mice (P < 0.05). Differentiating Raw with respect to time revealed a greater rate of bronchoconstriction for the WT during the initial 4 s, presumably reflecting the faster shortening velocities under these relatively unloaded conditions. Reverse transcriptase-polymerase chain reaction analysis revealed that the (+)insert myosin isoform mRNA content in the WT airways was 47.8 +/- 5.6%. We conclude that the presence of the (+)insert myosin isoform in the airways increases the rate of bronchoconstriction.
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PMID:Time course of airway mechanics of the (+)insert myosin isoform knockout mouse. 1295 48


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