Abstract:
:A system for studying Z-DNA formation in the Escherichia coli chromosome was developed. Prior investigations in recombinant plasmids showed that alternating (Pur-Pyr) sequences can adopt a left-handed Z-DNA conformation both in vitro and in vivo. We constructed mobile, transposon-based cassettes carrying cloned (Pur-Pyr) sequences containing an EcoRI site in the center. These cassettes were subsequently inserted into different locations in the E. coli chromosome in a random fashion. A number of stable insertions were characterized by Southern analysis and pulsed-field gel electrophoresis mapping. A cloned temperature-sensitive MEcoRI methylase was expressed in trans as the probe to study Z-DNA formation in vivo. In this system, the control EcoRI sites were quickly methylated when cells were placed at the permissive temperature. Strong inhibition of the methylation was observed, however, only for the EcoRI sites embedded in a 56-bp run of (C-G). In contrast, the shorter sequence of 32 bp did not show this behavior. Prior in vitro determinations revealed that the longer tract required less energy to stabilize the Z-helix than the shorter block. We conclude that the observed inhibition of methylation is due to Z-DNA formation in the E. coli chromosome. In vitro, these sequences undergo the B- to Z-DNA transition at a supercoil density of -0.026 for the 56-bp insert and -0.032 for the 32-bp block. Since only the longer (C-G) tract but not the shorter run adopted the left-handed conformation in the chromosome, we propose that these densities establish the boundaries in the different chromosomal loci investigated; these boundaries are in good agreement with the extremes found in plasmids.
journal_name
Proc Natl Acad Sci U S Aauthors
Lukomski S,Wells RDdoi
10.1073/pnas.91.21.9980subject
Has Abstractpub_date
1994-10-11 00:00:00pages
9980-4issue
21eissn
0027-8424issn
1091-6490journal_volume
91pub_type
杂志文章abstract::Cryptochromes are blue-light receptors mediating various light responses in plants and animals. The photochemical mechanism of cryptochromes is not well understood. It has been proposed that photoactivation of cryptochromes involves the blue-light-dependent photoreduction of flavin adenine dinucleotide via the electro...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1114579108
更新日期:2011-12-20 00:00:00
abstract::Results are reported showing that pituitary extracts stimulate growth of 3T3 cells, an established line of mouse fibroblast. Cells were cultured in medium containing an organic buffer (HEPES; N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid), which increases the serum requirement for cell growth. The pituitary grow...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.70.9.2702
更新日期:1973-09-01 00:00:00
abstract::The up-regulation of the 25-hydroxyvitamin D(3)-24-hydroxylase by 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] is well established and occurs at the transcriptional level through two vitamin D response elements in the promoter of the gene. However, the mechanism of down-regulation of the 24-hydroxylase by parathyroid ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.241516798
更新日期:2001-11-20 00:00:00
abstract::Language is classically thought to be supported by perisylvian cortical regions. Here we provide intracranial evidence linking the hippocampal complex to linguistic processing. We used direct recordings from the hippocampal structures to investigate whether theta oscillations, pivotal in memory function, track the amo...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1603312113
更新日期:2016-10-04 00:00:00
abstract::One of the strategies used by organisms to adapt to life under conditions of short energy supply is to use the by-product pyrophosphate to support cation gradients in membranes. Transport reactions are catalyzed by membrane-integral pyrophosphatases (PPases), which are classified into two homologous subfamilies: H(+)-...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1217816110
更新日期:2013-01-22 00:00:00
abstract::The pattern of antibody specificities in sera from patients with myasthenia gravis (MG) was determined by the ability of monoclonal antibodies against defined determinants on the acetylcholine receptor molecule to inhibit binding of the serum antibodies to receptor from human muscle. We found that MG patients produce ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.1.188
更新日期:1982-01-01 00:00:00
abstract::Control over the fluorescence of supramolecular assemblies is crucial for the development of chemosensors and light-emitting materials. Consequently, the postsynthetic modification of supramolecular structures via host-guest interactions has emerged as an efficient strategy in recent years that allows the facile tunin...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1702510114
更新日期:2017-03-21 00:00:00
abstract::Papain solubilized H-2a histocompatibility antigens (H-2Kk plus H-2Dd) have been purified by a large-scale procedure that can routinely provide 2-3 mg of heavy chain from 1 kg of mouse liver. The heavy chains were homogeneous by sodium dodecyl sulfate electrophoresis. Disc gel electrophoresis resolved two protein band...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.75.7.3322
更新日期:1978-07-01 00:00:00
abstract::The gene networks underlying closure of the optic fissure during vertebrate eye development are poorly understood. Here, we profile global gene expression during optic fissure closure using laser capture microdissected (LCM) tissue from the margins of the fissure. From these data, we identify a unique role for the C(2...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0812017106
更新日期:2009-02-03 00:00:00
abstract::A simple protocol for the rescue of a synthetic genome into a paramyxovirus has been developed. First, a synthetic Sendai virus-like RNA, containing the antisense coding region of the chloramphenicol acetyltransferase gene replacing the coding region of the Sendai virus genome, was transcribed from a cDNA. When introd...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.13.5537
更新日期:1991-07-01 00:00:00
abstract::We explore the interactions of CYT-19, a DExD/H-box protein that functions in folding of group I RNAs, with a well characterized misfolded species of the Tetrahymena ribozyme. Consistent with its function, CYT-19 accelerates refolding of the misfolded RNA to its native state. Unexpectedly, CYT-19 performs another reac...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0603127103
更新日期:2006-11-07 00:00:00
abstract::The prohibitin (PHB)-domain proteins are membrane proteins that regulate a variety of biological activities, including mechanosensation, osmotic homeostasis, and cell signaling, although the mechanism of this regulation is unknown. We have studied two members of this large protein family, MEC-2, which is needed for to...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0607465103
更新日期:2006-11-14 00:00:00
abstract::Horizontal cells of the carp retina possess dopamine receptors linked to adenylate cyclase. Isolated, intact horizontal cells respond to micromolar concentrations of dopamine, whereas nanomolar concentrations of haloperidol, (+)-butaclamol, and flupenthixol block the dopamine response. Preincubation in Ringer's soluti...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.10.3350
更新日期:1982-05-01 00:00:00
abstract::Regulation of the turnover of triglycerides in adipose tissue requires the continuous provision of 3-glycerophosphate, which may be supplied by the metabolism of glucose or by glyceroneogenesis, the de novo synthesis of 3-glycerophosphate from sources other than hexoses or glycerol. The importance of glyceroneogenesis...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.022616299
更新日期:2002-01-22 00:00:00
abstract::A photoreactive derivative of epidermal growth factor (EGF) has been used to identify and specifically label a membrane receptor for EGF on mouse 3T3 cells. Photoactivable EGF, labeled with 125I, was incubated with 3T3 cells and then photolyzed in situ to generate a nitrene capable of reacting with a wide variety of c...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.74.7.2790
更新日期:1977-07-01 00:00:00
abstract::A peptide containing 31 amino acids with inhibin-like activity has been synthesized by the solid-phase method. The synthetic product was shown to be homogeneous in high-performance liquid chromatography and paper electrophoresis. In the mouse pituitary incubation system, the follitropin-suppressing activity of the syn...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.81.17.5399
更新日期:1984-09-01 00:00:00
abstract::"Evolution behaves like a tinkerer" (François Jacob, Science, 1977). Software systems provide a singular opportunity to understand biological processes using concepts from network theory. The Debian GNU/Linux operating system allows us to explore the evolution of a complex network in a unique way. The modular design d...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1115960108
更新日期:2011-12-13 00:00:00
abstract::The leukemic fusion gene AML1-MDS1-EVI1 (AME) encodes a chimeric transcription factor that results from the t(3,21)(q26;q22) translocation seen in patients with acute myeloid leukemia, with therapy-related myelodysplastic syndrome, or with chronic myeloid leukemia in blast crisis. The myeloid transcription factor CEBP...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0404731101
更新日期:2004-09-07 00:00:00
abstract::In mitosis, chromosome, cytoskeleton, and organelle dynamics must be coordinated for successful cell division. Here, we present evidence for a role for Arf1, a small GTPase associated with the Golgi apparatus, in the orchestration of mitotic Golgi breakdown, chromosome segregation, and cytokinesis. We show that early ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.2234055100
更新日期:2003-11-11 00:00:00
abstract::The severity of Helicobacter pylori-related disease is correlated with a pathogenicity island (the Cag region of about 26 genes) whose presence is associated with the up-regulation of an IL-8 cytokine inflammatory response in gastric epithelial cells. Statistical analysis of the Cag gene sequences calculated from the ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.12.7011
更新日期:1999-06-08 00:00:00
abstract::Soluble epoxide hydrolase (sEH) is an emerging therapeutic target in a number of diseases that have inflammation as a common underlying cause. sEH limits tissue levels of cytochrome P450 (CYP) epoxides derived from omega-6 and omega-3 polyunsaturated fatty acids (PUFA) by converting these antiinflammatory mediators in...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1422590112
更新日期:2015-01-13 00:00:00
abstract::Control over structural transformations in supramolecular entities by external stimuli is critical for the development of adaptable and functional soft materials. Herein, we have designed and synthesized a dipyridyl donor containing a central Z-configured stiff-stilbene unit that self-assembles in the presence of two ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1408620111
更新日期:2014-06-17 00:00:00
abstract::Four overlapping cosmid clones were constructed that contain the complete genome of the attenuated Oka strain of VZV. Transfection of human melanoma cells with the four cosmids resulted in production of infectious VZV. A double-stranded oligonucleotide, encoding a stop codon in all three open reading frames, was inser...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.15.7376
更新日期:1993-08-01 00:00:00
abstract::The protein dystrophin, normally found on the cytoplasmic surface of skeletal muscle cell membranes, is absent in patients with Duchenne muscular dystrophy as well as mdx (X-linked muscular dystrophy) mice. Although its primary structure has been determined, the precise functional role of dystrophin remains the subjec...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.8.3710
更新日期:1993-04-15 00:00:00
abstract::Integration sites for many retrotransposons and retroviruses are determined by interactions between retroelement-encoded integrases and specific DNA-bound proteins. The Saccharomyces retrotransposon Ty5 preferentially integrates into heterochromatin because of interactions between Ty5 integrase and the heterochromatin...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1103665108
更新日期:2011-12-20 00:00:00
abstract::Recent studies with fibroblasts have shown that peptidylhydroxyproline formation begins toward the end of the log phase of growth and is an expression of the activity of the enzyme, collagen proline hydroxylase, which increase in late log-phase cells. This communication reports a two- to fivefold increase in hydroxyla...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.66.2.552
更新日期:1970-06-01 00:00:00
abstract::Aspartate transcarbamoylase (EC 2.1.3.2) from Escherichia coli contains six zinc ions per molecule. Renaturation studies of this allosteric enzyme and its isolated subunits show that the metal binding site is in the regulatory polypeptide chain. Ultraviolet difference spectra of the cadmium and zinc derivatives have b...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.68.5.1019
更新日期:1971-05-01 00:00:00
abstract::I demonstrate the existence in protein domain sequences of sets of statistically significant periodic signals, characteristic of the architectures of those domains. It is shown that, although the frequencies of the signals characteristic of a particular architecture have definite wave numbers, they can occur in any ph...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.95.15.8580
更新日期:1998-07-21 00:00:00
abstract::Symmetric and asymmetric dimethylation of arginine are isomeric protein posttranslational modifications with distinct biological effects, evidenced by the methylation of arginine 3 of histone H4 (H4R3): symmetric dimethylation of H4R3 leads to repression of gene expression, while asymmetric dimethylation of H4R3 is as...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1106946108
更新日期:2011-12-20 00:00:00
abstract::A cloned Bacillus subtilis gene (sprE) expressed only during the stationary growth phase is shown to encode the subtilisin E protease, an enzyme associated with sporulation. We have determined the DNA sequence of the sprE promoter region and the promoter-proximal half of the structural gene. The sprE gene codes for a ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.81.4.1184
更新日期:1984-02-01 00:00:00