Abstract:
:We have performed thin-section electron microscopy on muscle fibers fixed in different mechanically monitored states, in order to identify structural changes in myosin crossbridges associated with force production and maintenance. Tension and stiffness of fibers from glycerinated Lethocerus flight muscle were monitored during a sequence of conditions using AMPPNP and then AMPPNP plus increasing concentrations of ethylene glycol, which brought fibers through a graded sequence from rigor relaxation. Two intermediate crossbridge forms distinct from the rigor or relaxed forms were observed. The first was produced by AMPPNP at 20 degrees C, which reduced isometric tension 60 to 70% below rigor level without reducing rigor stiffness. Electron microscopy of these fibers showed that, in spite of the drop in tension, no obvious change from the 45 degrees crossbridge angle characteristic of rigor occurred. However, the thick filament ends of the crossbridges were altered from their rigor positions, so that they now marked a 14.5 nm repeat, and formed four separate origins at each crossbridge level. The bridges were also less slewed and bent than rigor bridges, as seen in transverse sections. The second crossbridge form was seen in glycol-AMPPNP at 4 degrees C, just below the glycol concentration that produced mechanical relaxation. These fibers retained 90% of rigor stiffness at 40 Hz oscillation, but would not bear sustained tension. Stiffness was also high in the presence of calcium at room temperature under similar conditions. Electron microscopy showed crossbridges projecting from the thick filaments at an angle that centered around 90 degrees, rather than the 45 degree angle familiar from rigor. This coupling of relaxed appearance with persistent stiffness suggests that the 90 degree form may represent a weakly attached crossbridge state like that proposed to precede force development in current models of the crossbridge power stroke.
journal_name
J Mol Bioljournal_title
Journal of molecular biologyauthors
Reedy MC,Reedy MK,Tregear RTdoi
10.1016/0022-2836(88)90582-7subject
Has Abstractpub_date
1988-11-20 00:00:00pages
357-83issue
2eissn
0022-2836issn
1089-8638pii
0022-2836(88)90582-7journal_volume
204pub_type
杂志文章abstract::We have developed a self-assembly system for nucleosome arrays in which recombinant, post-translationally unmodified histone proteins are combined with DNA of defined-sequence to form chromatin higher-order structure. The nucleosome arrays obtained are highly homogeneous and sediment at 53S when maximally folded in 1m...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/s0022-2836(03)00025-1
更新日期:2003-03-14 00:00:00
abstract::TWINKLE is the helicase at the mitochondrial DNA (mtDNA) replication fork in mammalian cells. Mutations in the PEO1 gene, which encodes TWINKLE, cause autosomal dominant progressive external ophthalmoplegia (AdPEO), a disorder associated with deletions in mtDNA. Here, we characterized seven different AdPEO-causing mut...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2008.01.035
更新日期:2008-03-28 00:00:00
abstract::Retroviruses are a family of widespread small animal viruses about 110 nm in diameter, composed of an inner core surrounded by an outer envelope formed of a lipid bilayer of cellular origin in which are anchored viral glycoproteins. The inner core is formed by an outer shell of capsid protein molecules (CA protein) su...
journal_title:Journal of molecular biology
pub_type: 杂志文章,评审
doi:10.1006/jmbi.1995.0635
更新日期:1995-12-08 00:00:00
abstract::The extracellular matrix is a dynamic environment that constantly undergoes remodelling and degradation during vital physiological processes such as angiogenesis, wound healing, and development. Unbalanced extracellular matrix breakdown is associated with many diseases such as arthritis, cancer and fibrosis. Interstit...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2006.06.079
更新日期:2006-09-08 00:00:00
abstract::pBR322 DNA, linearized by lysis of an oxolinic acid-treated culture of Escherichia coli strain DK6recA- (pBR322) with sodium dodecyl sulfate, was purified, treated with DNA polymerase in the presence of the four deoxynucleoside triphosphates, and ligated to DNA linkers containing the XhoI recognition sequence. Most of...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(85)90324-9
更新日期:1985-01-05 00:00:00
abstract::Bacterial cell shape is dictated by the cell wall, a plastic structure that must adapt to growth and division whilst retaining its function as a selectively permeable barrier. The modulation of cell wall structure is achieved by a variety of enzymatic functions, all of which must be spatially regulated in a precise ma...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2007.07.022
更新日期:2007-09-28 00:00:00
abstract::We have examined the nuclease sensitivity of the 5' flanking region of the rabbit beta 1 globin gene in bone marrow nuclei and in supercoiled plasmids. A DNase I hypersensitive site was found about 100 base-pairs 5' to the cap site in bone marrow nuclei. S1 nuclease can introduce a specific double-strand cut in the DN...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(85)90373-0
更新日期:1985-07-20 00:00:00
abstract::Like other RNA molecules, RNase P RNA (RPR) is composed of domains, and these have different functions. Here, we provide data demonstrating that the catalytic (C) domain of Escherichia coli (Eco) RPR when separated from the specificity (S) domain mediates cleavage using various model RNA hairpin loop substrates. Compa...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2012.05.020
更新日期:2012-09-14 00:00:00
abstract::The structure of mucor pusillus pepsin (EC 3.4.23.6), the aspartic proteinase from Mucor pusillus, has been refined to a crystallographic R-factor of 16.2% at 2.0 A resolution. The positions of 2638 protein atoms, 221 solvent atoms and a sulphate ion have been determined with an estimated root-mean-square (r.m.s.) err...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:
更新日期:1993-03-05 00:00:00
abstract::The tandemly repeated sea urchin alpha-histone genes are developmentally regulated. These genes are transcribed up to the early blastula stage and permanently silenced as the embryos approach gastrulation. As previously described, expression of the alpha-H2A gene depends on the binding of the MBF-1 activator to the 5'...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2006.10.098
更新日期:2007-02-02 00:00:00
abstract::Rhodobacter sphaeroides rpoE encodes a 19.2 kDa protein, sigma(E), related to members of the extra-cytoplasmic function subfamily of eubacterial RNA polymerase sigma factors. We demonstrate that sigma(E) directs transcription from rpoE P1, the promoter for the rpoEchrR operon, and from cycA P3, a promoter for the cyto...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1999.3263
更新日期:1999-11-26 00:00:00
abstract::Riboswitches are cis-acting genetic regulatory elements found commonly in bacterial mRNAs that consist of a metabolite-responsive aptamer domain coupled to a regulatory switch. Purine riboswitches respond to intracellular concentrations of either adenine or guanine/hypoxanthine to control gene expression. The aptamer ...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2006.04.003
更新日期:2006-06-09 00:00:00
abstract::The free form of ribonuclease T1 (RNase T1) has been crystallized at neutral pH, and the three-dimensional structure of the enzyme has been determined at 1.5 A nominal resolution. Restrained least-squares refinement yielded an R value of 14.3% for 12,623 structure amplitudes. The high resolution of the structure analy...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(91)90215-r
更新日期:1991-11-20 00:00:00
abstract::The nuclear pore complex is the sole mediator of bidirectional transport between the nucleus and cytoplasm. Nup358 is a metazoan-specific nucleoporin that localizes to the cytoplasmic filaments and provides several binding sites for the mobile nucleocytoplasmic transport machinery. Here we present the crystal structur...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2013.01.021
更新日期:2013-04-26 00:00:00
abstract::Wild-type hen lysozyme has been converted from its soluble native state into highly organized amyloid fibrils. In order to achieve this conversion, conditions were chosen to promote partial unfolding of the native globular fold and included heating of low-pH solutions and addition of organic solvents. Two peptides der...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.2000.3862
更新日期:2000-07-14 00:00:00
abstract::Protein folding is directed by the sequence of sidechains along the polypeptide backbone, but despite this the developement of sidechain interactions during folding is not well understood. Here, the thiol-active reagent, dithio-nitrobenzoic acid (DTNB), is used to probe the exposure of the cysteine sidechain thiols in...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2006.09.014
更新日期:2006-12-08 00:00:00
abstract::The production of recombinant proteins in Escherichia coli frequently results in the formation of insoluble protein aggregates called inclusion bodies (IBs). The determinants of IB formation remain poorly understood and are of much interest for biotechnological and research applications, as well as offering insight in...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2016.02.016
更新日期:2016-03-27 00:00:00
abstract::Catalytic antibodies 6D9 and 9C10, which were induced by immunization with a haptenic transition-state analog (TSA), catalyze the hydrolysis of a nonbioactive chloramphenicol monoester derivative to generate a bioactive chloramphenicol. These antibodies stabilize the transition state to catalyze the hydrolysis reactio...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2007.03.023
更新日期:2007-05-25 00:00:00
abstract::DnaB helicase is a ring-shaped hexamer that unwinds DNA at a replication fork. To understand how this protein interacts with DNA during unwinding, DnaB from Thermus aquaticus was incubated with chemically modified forked-duplex DNA substrates and the unwinding rates were measured. Unwinding was inhibited by modificati...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.2000.3965
更新日期:2000-08-11 00:00:00
abstract::We use a synthetic "primed bubble-duplex" model elongation complex developed previously to examine certain structural and thermodynamic features of the transcription elongation complex of Escherichia coli. The nucleic acid framework of this model complex consists of a linear base-paired DNA molecule with a central "bu...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1999.2814
更新日期:1999-06-25 00:00:00
abstract::Type I DNA methyltransferases are complex multisubunit enzymes that methylate a specific base in each half of an asymmetric bipartite DNA recognition sequence. The specificity (S) subunit contains two corresponding DNA sequence recognition domains, plus a number of conserved regions which interact with two modificatio...
journal_title:Journal of molecular biology
pub_type: 杂志文章,评审
doi:10.1006/jmbi.1994.1624
更新日期:1994-10-14 00:00:00
abstract::We have investigated the structure of complexes formed between a series of poly(A)n (n = 30 to 480) and HD40 (helix-destabilizing protein, molecular weight of 40,000), the major protein component of 30 S heterogeneous nuclear ribonucleoprotein particles (hnRNP) from the brine shrimp Artemia salina. Protein HD40 is sim...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(83)90039-6
更新日期:1983-12-25 00:00:00
abstract::Cytoplasmic Ca2+ signals are highly regulated by various ion transporters, including the inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R), which functions as a Ca2+ release channel on the endoplasmic reticulum membrane. Crystal structures of the two N-terminal regulatory regions from type 1 IP(3)R have been repo...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2007.08.057
更新日期:2007-11-09 00:00:00
abstract::The homotetrameric Escherichia coli single-stranded DNA binding protein (SSB) plays a central role in DNA replication, repair and recombination. E. coli SSB can bind to long single-stranded DNA (ssDNA) in multiple binding modes using all four subunits [(SSB)65 mode] or only two subunits [(SSB)35 binding mode], with th...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2014.12.020
更新日期:2015-02-27 00:00:00
abstract::Many proteins have small-molecule binding pockets that are not easily detectable in the ligand-free structures. These cryptic sites require a conformational change to become apparent; a cryptic site can therefore be defined as a site that forms a pocket in a holo structure, but not in the apo structure. Because many p...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2016.01.029
更新日期:2016-02-22 00:00:00
abstract::We have examined the structure of hemoglobin S fibers, which are associated into large bundles, or fascicles. Electron micrographs of embedded and cross-sectioned fascicles provide an end-on view of the component fibers. The cross-sectional images are rotationally blurred as a result of the twist of the fiber within t...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(88)90322-1
更新日期:1988-01-20 00:00:00
abstract::Pathogenic strains of Helicobacter pylori use a type IV secretion system (T4SS) to deliver the toxin CagA into human host cells. The T4SS, along with the toxin itself, is coded into a genomic insert, which is termed the cag pathogenicity island. The cag pathogenicity island contains about 30 open-reading frames, for m...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2008.12.018
更新日期:2009-02-13 00:00:00
abstract::p50 protein is a member of the Y-box binding transcription factor family and is a counterpart of YB-1 protein. The generic microchip was used to analyze the sequence specificity of p50 binding to single (ss) and double-stranded (ds) oligodeoxyribonucleotides. The generic microchip contained 4,096 single-stranded octad...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/s0022-2836(02)00937-3
更新日期:2002-11-15 00:00:00
abstract::Residues specifying aminoacylation by yeast tyrosyl-tRNA synthetase (TyrRS) of the tRNA-like structure present at the 3'-end of brome mosaic virus (BMV) RNA were determined by the in vitro approach using phage T7 transcripts. They correspond to nucleotides equivalent to base-pair C1-G72 and discriminator base A73 in t...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.2001.4654
更新日期:2001-06-01 00:00:00
abstract::Hepatocyte nuclear factor 1 (HNF1) is a dimeric homeoprotein expressed in hepatocytes and in a few other epithelial cells where it helps regulate the expression of a specific subset of genes. In an attempt to identify novel target genes for HNF1 and to assess the distribution of its target sites within the vertebrate ...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1996.0760
更新日期:1997-02-21 00:00:00