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101.
Lednev IK Ermolenkov VV Higashiya S Popova LA Topilina NI Welch JT 《Biophysical journal》2006,91(10):3805-3818
A de novo 687-amino-acid residue polypeptide with a regular 32-amino-acid repeat sequence, (GA)3GY(GA)3GE(GA)3GH(GA)3GK, forms large β-sheet assemblages that exhibit remarkable folding properties and, as well, form fibrillar structures. This construct is an excellent tool to explore the details of β-sheet formation yielding intimate folding information that is otherwise difficult to obtain and may inform folding studies of naturally occurring materials. The polypeptide assumes a fully folded antiparallel β-sheet/turn structure at room temperature, and yet is completely and reversibly denatured at 125°C, adopting a predominant polyproline II conformation. Deep ultraviolet Raman spectroscopy indicated that melting/refolding occurred without any spectroscopically distinct intermediates, yet the relaxation kinetics depend on the initial polypeptide state, as would be indicative of a non-two-state process. Thermal denaturation and refolding on cooling appeared to be monoexponential with characteristic times of ~1 and ~60 min, respectively, indicating no detectable formation of hairpin-type nuclei in the millisecond timescale that could be attributed to nonlocal “nonnative” interactions. The polypeptide folding dynamics agree with a general property of β-sheet proteins, i.e., initial collapse precedes secondary structure formation. The observed folding is much faster than expected for a protein of this size and could be attributed to a less frustrated free-energy landscape funnel for folding. The polypeptide sequence suggests an important balance between the absence of strong nonnative contacts (salt bridges or hydrophobic collapse) and limited repulsion of charged side chains. 相似文献
102.
Marcio Carvalho de Moretzsohn Mark S Hopkins Sharon E Mitchell Stephen Kresovich Jose Francisco Montenegro Valls Marcio Elias Ferreira 《BMC plant biology》2004,4(1):11
Background
The genus Arachis is native to a region that includes Central Brazil and neighboring countries. Little is known about the genetic variability of the Brazilian cultivated peanut (Arachis hypogaea, genome AABB) germplasm collection at the DNA level. The understanding of the genetic diversity of cultivated and wild species of peanut (Arachis spp.) is essential to develop strategies of collection, conservation and use of the germplasm in variety development. The identity of the ancestor progenitor species of cultivated peanut has also been of great interest. Several species have been suggested as putative AA and BB genome donors to allotetraploid A. hypogaea. Microsatellite or SSR (Simple Sequence Repeat) markers are co-dominant, multiallelic, and highly polymorphic genetic markers, appropriate for genetic diversity studies. Microsatellite markers may also, to some extent, support phylogenetic inferences. Here we report the use of a set of microsatellite markers, including newly developed ones, for phylogenetic inferences and the analysis of genetic variation of accessions of A. hypogea and its wild relatives. 相似文献103.
Burlandy FM Ferreira DF Rebello MA 《Zeitschrift für Naturforschung. C, Journal of biosciences》2004,59(1-2):127-131
Cyclopentenone prostaglandins (PGs) exhibit antiviral activity against RNA and DNA viruses in mammalian cell lines, and this effect has been associated with the induction of a heat shock protein (hsp70). We investigated the effect of prostaglandin A1 (PGA1) on the replication of vesicular stomatitis virus (VSV) in Aedes albopictus (mosquito) cells. PGA1 was found to inhibit VSV replication dose dependently. Virus yield was reduced to 50% (3 microg PGA1/ml) and to 95% with 8 microg PGA1/ml. Even with the dramatic reduction of virus production observed in cells treated with PGA1, VSV-specific protein synthesis was unaltered. Treatment of cells with PGA1 (5 microg/ml) stimulated the synthesis of a polypeptide identified as a heat-shock protein (hsp) by immunoblot analysis. PGA1 induced hsp70 synthesis in uninfected cells. However, in VSV-infected cells the induction of hsp70 by PGA1 was reduced. This is the first report of antiviral effects of PGs affecting the replication of VSV in a mosquito cell line. 相似文献
104.
Visualization of early chromosome condensation: a hierarchical folding, axial glue model of chromosome structure 总被引:10,自引:0,他引:10
Kireeva N Lakonishok M Kireev I Hirano T Belmont AS 《The Journal of cell biology》2004,166(6):775-785
Current models of mitotic chromosome structure are based largely on the examination of maximally condensed metaphase chromosomes. Here, we test these models by correlating the distribution of two scaffold components with the appearance of prophase chromosome folding intermediates. We confirm an axial distribution of topoisomerase IIalpha and the condensin subunit, structural maintenance of chromosomes 2 (SMC2), in unextracted metaphase chromosomes, with SMC2 localizing to a 150-200-nm-diameter central core. In contrast to predictions of radial loop/scaffold models, this axial distribution does not appear until late prophase, after formation of uniformly condensed middle prophase chromosomes. Instead, SMC2 associates throughout early and middle prophase chromatids, frequently forming foci over the chromosome exterior. Early prophase condensation occurs through folding of large-scale chromatin fibers into condensed masses. These resolve into linear, 200-300-nm-diameter middle prophase chromatids that double in diameter by late prophase. We propose a unified model of chromosome structure in which hierarchical levels of chromatin folding are stabilized late in mitosis by an axial "glue." 相似文献
105.
106.
Elizabeth D. Hughes Yun Yan Qu Suzanne J. Genik Robert H. Lyons Christopher D. Pacheco Andrew P. Lieberman Linda C. Samuelson Igor O. Nasonkin Sally A. Camper Margaret L. Van Keuren Thomas L. Saunders 《Mammalian genome》2007,18(8):549-558
Genetically modified mouse strains derived from embryonic stem (ES) cells are powerful tools for gene function analysis. ES
cells from the C57BL/6 mouse strain are not widely used to generate mouse models despite the advantage of a defined genetic
background. We assessed genetic variation in six such ES cell lines with 275 SSLP markers. Compared to C57BL/6, Bruce4 differed
at 34 SSLP markers and had significant heterozygosity on three chromosomes. BL/6#3 and Dale1 ES cell lines differed at only
3 SSLP makers. The C2 and WB6d ES cell lines differed at 6 SSLP markers. It is important to compare the efficiency of producing
mouse models with available C57BL/6 ES cells relative to standard 129 mouse strain ES cells. We assessed genetic stability
(the tendency of cells to become aneuploid) in 110 gene-targeted ES cell clones from the most widely used C57BL/6 ES cell
line, Bruce4, and 710 targeted 129 ES cell clones. Bruce4 clones were more likely to be aneuploid and unsuitable for ES cell-mouse
chimera production. Despite their tendency to aneuploidy and consequent inefficiency, use of Bruce4 ES cells can be valuable
for models requiring behavioral studies and other mouse models that benefit from a defined C57BL/6 background.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
107.
Artoni RF Vicari MR Endler AL Cavallaro ZI de Jesus CM de Almeida MC Moreira-Filho O Bertollo LA 《Genetica》2006,127(1-3):277-284
B chromosomes in Prochilodus lineatus, a migratory neotropical fish, were analyzed in a comparative study among populations from the Dourada lagoon (State of Paraná, Brazil) and from Mogi-Guaçu river (State of São Paulo, Brazil). The data on C-banding and fluorescent in situ hybridization with a satellite DNA probe (SATH1), indicate that the small metacentric B chromosome might correspond to an isochromosome. On the other hand, both populations presented a distinct set of B chromosomes, differentiated either by their number and by the presence of variant B types in the population from Mogi-Guaçu river. The present results indicate that the B chromosomes of P. lineatus should have an ancient origin, and have undergone a differential evolutionary pathway among distinct populations. 相似文献
108.
Structural analysis of an Echinococcus granulosus actin-fragmenting protein by small-angle x-ray scattering studies and molecular modeling 下载免费PDF全文
Grimm ED Portugal RV de Oliveira Neto M Martins NH Polikarpov I Zaha A Ferreira HB 《Biophysical journal》2006,90(9):3216-3223
The Echinococcus granulosus actin filament-fragmenting protein (EgAFFP) is a three domain member of the gelsolin family of proteins, which is antigenic to human hosts. These proteins, formed by three or six conserved domains, are involved in the dynamic rearrangements of the cytoskeleton, being responsible for severing and capping actin filaments and promoting nucleation of actin monomers. Various structures of six domain gelsolin-related proteins have been investigated, but little information on the structure of three domain members is available. In this work, the solution structure of the three domain EgAFFP has been investigated through small-angle x-ray scattering (SAXS) studies. EgAFFP exhibits an elongated molecular shape. The radius of gyration and the maximum dimension obtained by SAXS were, respectively, 2.52 +/- 0.01 nm and 8.00 +/- 1.00 nm, both in the absence and presence of Ca2+. Two different molecular homology models were built for EgAFFP, but only one was validated through SAXS studies. The predicted structure for EgAFFP consists of three repeats of a central beta-sheet sandwiched between one short and one long alpha-helix. Possible implications of the structure of EgAFFP upon actin binding are discussed. 相似文献
109.
Barreto da Silveira Ismênia Glauce de Oliveira da Silva Neto Jorge Alves da Silva Ferreira Jéssica Silva Tatiane Severo Holanda Ioná Santos Araújo 《Molecular biology reports》2021,48(10):6887-6895
Molecular Biology Reports - Leprosy is a chronic infectious disease caused by Mycobacterium leprae and persists as a serious public health problem in Brazil. This microorganism is inculturable,... 相似文献
110.
Summary Ubiquinone-10 (Q10) production was measured in batch cultures of Paracoccus denitrificans grown for 8 h at increasing oxygen concentrations (0–21 % O2 in the sparging gas). Whereas the cellular level of Q10 decreased monotonically from 1.2 to 0.5 mol/g d.w., the total yield of Q10 was maximal at 2.5 % O2 and amounted to 350 nmol (0.3 mg) per L of culture. 相似文献