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21.
Kanga S Bernard D Mager-Heckel AM Erpapazoglou Z Mattiroli F Sixma TK Léon S Urban-Grimal D Tarassov I Haguenauer-Tsapis R 《PloS one》2012,7(6):e38071
The ubiquitin system is known to be involved in maintaining the integrity of mitochondria, but little is known about the role of deubiquitylating (DUB) enzymes in such functions. Budding yeast cells deleted for UBP13 and its close homolog UBP9 displayed a high incidence of petite colonies and slow respiratory growth at 37°C. Both Ubp9 and Ubp13 interacted directly with Duf1 (DUB-associated factor 1), a WD40 motif-containing protein. Duf1 activates the DUB activity of recombinant Ubp9 and Ubp13 in vitro and deletion of DUF1 resulted in the same respiratory phenotype as the deletion of both UBP9 and UBP13. We show that the mitochondrial defects of these mutants resulted from a strong decrease at 37°C in the de novo biosynthesis of Atp9, a membrane-bound component of ATP synthase encoded by mitochondrial DNA. The defect appears at the level of ATP9 mRNA translation, while its maturation remained unchanged in the mutants. This study describes a new role of the ubiquitin system in mitochondrial biogenesis. 相似文献
22.
Ertan Sait Kurtar Ahmet Balkaya Dilek Kandemir 《Plant Cell, Tissue and Organ Culture》2016,127(2):497-511
The production of large numbers of haploids is the crucial point of the dihaploidisation process. Although in vitro haploid plants were successfully produced by irradiated pollen technique in winter squash (Cucurbita maxima Duch.) and pumpkin (Cucurbita moschata Duch.), the frequency is still insufficient for using in a large-scale breeding programme. Thus, the present study was conducted to determine the efficacy of the anther culture technique on the production of in vitro haploids in the aforementioned species for which there have been no successful reports concerning by androgenesis. The anthers at uninucleate microspore stage were collected at different florescence times and then cultured on a solid MS medium supplemented by different combinations of 2,4-D (2,4-dichlorophenoxyacetic acid), BAP (6-benzylaminopurine), KN (kinetin) with the constant addition of NAA (naphthalene acetic acid) to induce callogenesis, embryogenesis and plantlet initiation. The combination of PGR, genotype and anther collection time played an important role in the androgenic response. The highest response was obtained from 57S?21 and G9 lines with the combination of 2.0 or 4.0 mg/l BAP?+?0.05 mg/l NAA (E6 medium) at the first anther collection time. Plantlets were regenerated and rooted on MS medium supplemented by 0.01 mg/l IAA. In total, 74 plants were recovered and propagated with micro-cuttings. The ploidy analyses revealed that 35 plants (47.3?%) were haploid (n?=?20), and the others (52.7?%) were diploid (2n?=?40). 相似文献
23.
Zeynep Kurkcuoglu Ahmet Bakan Duygu Kocaman Ivet Bahar Pemra Doruker 《PLoS computational biology》2012,8(9)
Catalytic loop motions facilitate substrate recognition and binding in many enzymes. While these motions appear to be highly flexible, their functional significance suggests that structure-encoded preferences may play a role in selecting particular mechanisms of motions. We performed an extensive study on a set of enzymes to assess whether the collective/global dynamics, as predicted by elastic network models (ENMs), facilitates or even defines the local motions undergone by functional loops. Our dataset includes a total of 117 crystal structures for ten enzymes of different sizes and oligomerization states. Each enzyme contains a specific functional/catalytic loop (10–21 residues long) that closes over the active site during catalysis. Principal component analysis (PCA) of the available crystal structures (including apo and ligand-bound forms) for each enzyme revealed the dominant conformational changes taking place in these loops upon substrate binding. These experimentally observed loop reconfigurations are shown to be predominantly driven by energetically favored modes of motion intrinsically accessible to the enzyme in the absence of its substrate. The analysis suggests that robust global modes cooperatively defined by the overall enzyme architecture also entail local components that assist in suitable opening/closure of the catalytic loop over the active site. 相似文献
24.
Georges TawilAnders Viksø-Nielsen Agnès Rolland-SabatéPaul Colonna Alain Buléon 《Carbohydrate polymers》2012,87(1):46-52
A new α-amylase from Anoxybacillus flavothermus (AFA) was found to be effective in hydrolyzing raw starch in production of glucose syrup at temperatures below the starch gelatinization temperature. AFA is very efficient, leading to 77% hydrolysis of a 31% raw starch suspension. The final hydrolysis degree is reached in 2-3 h at starch concentrations lower than 15% and 8-24 h at higher concentrations. AFA is also very efficient in hydrolyzing the crystalline domains in the starch granule. The major A-type crystalline structure is more rapidly degraded than amorphous domains in agreement with the observed preferential hydrolysis of amylopectin. Amylose-lipid complexes are degraded in a second step, yielding amylose fragments which then re-associate into B-type crystalline structures forming the final α-amylase resistant fraction. The mode of action of AFA and the factors limiting complete hydrolysis are discussed in details. 相似文献
25.
Silan F Gultekin Y Atik S Kilinc D Alan C Yildiz F Uludag A Ozdemir O 《Molecular biology reports》2012,39(2):1595-1599
Prostate cancer is a common malignancy that develops by structural mutation(s) and/or other genetic alterations in specific genes.The G to T transversions in codon 12 and C to T transitions in codon 13 of KRAS proto-oncogene are predominant point mutations that occur in about 20% of different cancers in human. In the current study it was aimed to investigate the prevalence and predictive significance of KRAS mutations in patients with prostate carcinomas. In a total of 30 fresh tumoural tissue specimens were investigated in patients with prostate carcinoma. All tumoural specimens were histo-pathologically diagnosed and genotyped for codon 12, 13 KRAS point mutations by reverse hybridisation and direct sequencing methods. KRAS mutations were found in 12 (40%) samples with 29 samples deriving from adenocarcinomas and 1 sample was small cell prostate carcinoma. In 1 (3.44%) sample codon 12 was found to be mutated and in 2 (6.8%) samples codon 13 and in 9 (31%) samples combined codon 12 and 13 were found to be mutated particularly in higher grade of tumoural tissues. Our study, based on representative collection of human prostate tumours, indicates that combined mutations in codons 12 and 13 KRAS are relatively infrequent and most commonly occur in prostate carcinomas. 相似文献
26.
27.
Donald J. Cummings Léon Belcour Claude Grandchamp 《Molecular & general genetics : MGG》1979,171(3):239-250
Summary Mitochondrial (Mt) DNA from mitochondrial mutants of race s Podospora anserina and from senescent cultures of races s and A was examined. In mutants, we observed that fewer full length circles (31 ) were present; instead, smaller circles characteristic for each mutant sudied were found. Eco Rl digestion of these mutant MtDNAs indicated that in certain mutants, although specific fragments were absent, the total molecular weight of the fragments was not much different than wild-type.The properties of senescent MtDNA was strikingly different from either wild-type or mutant Mt DNA. First, a multimeric set of circular DNA was observed for both race s and A, with a monomeric repeat size of 0.89 . These circles ranged in size from 0.89 to greater than 20 ; only one molecule out of some 200 molecules was thought to be of full length (31 ). Density gradient analysis showed that there were two density species: a majority were at the same density as wild-type (1.694 g/cm3) and a second at 1.699 g/cm3. Most of the circular molecules from MtDNA isolated by either total DNA extraction or by extraction of DNA from isolated mitochondria were contained in the heavy DNA fraction. Eco R1 enzymatic digestion indicated that the light DNA had several fragments (amounting to about 23×106 daltons) missing, compared with young, wild-type MtDNA. Heavy senescent MtDNA was not cleaved by Eco R1. Analysis with Hae III restriction endonuclease showed also that light senescent MtDNA was missing certain fragments. Heavy MtDNA of average size 20×106 daltons, yielded only one fragment, 2,500 bp long, by digestion with Hae III restriction endonuclease. Digestion of heavy DNA with Alu I enzyme yielded 10 fragments totalling 2,570 bp. By three criteria, electron-microscopy, Eco R1 and Hae digestion, we conclude that the heavy MtDNA isolated from senescent cultures of Podospora anserina consisted of a monomeric tandemly repeating subunit of about 2,600 bp length.These results on the properties of senescent MtDNA are discussed with regard to the published properties of the rho
- mutation in the yeast, S. cerevisiae. 相似文献
28.
Helichrysum sanguineum, Helichrysum pamphylicum, Helichrysum orientale, Helichrysum noeanum (Asteraceae) are medicinal plants. For centuries, they have been used as tea in Turkey because of their medicinal properties. So far no scientific evidence has been found in a literature survey regarding the genotoxic effects of these plants. This work evaluated the genotoxic effects on human lymphocyte cultures induced by methanol extracts of these plants, assayed in different concentrations (0.01, 0.05, 0.1, 0.5 and 1 mg/mL). According to the results, Helichrysum noeanum, Helichrysum pamphylicum and Helichrysum sanguineum induced the formation of micronuclei and decreased the mitotic and replication indexes. Helichrysum orientale did not affect these parameters, whereas Helichrysum noeanum, Helichrysum pamphylicum and Helichrysum sanguineum were clearly genotoxic. They should therefore not be used freely in alternative medicine, although their antiproliferative activity may suggest antimitotic and anticarcinogenic properties. Helichrysum orientale could be used in alternative medicine. 相似文献
29.
Native starch granules from wheat have been subjected to enzymatic depolymerization with an alpha-amylase from Bacillus subtilis. Crystallites made from short-chain amylose and residues from mild acid hydrolysis have been also tested. Electron microscopy, particle size analysis, DSC, and x-ray diffractometry reveal that enzymatic degradation occurs granule by granule. Gel permeation chromatography shows off the macromolecular nature of the remaining material. In contrast, acid erodes simultaneously all the granules, leading to a splitting into small particles. Crystalline fractions are completely degraded by alpha-amylase. These results support evidence for an active disentanglement of chains, carried out by the different subsites of alpha-amylase molecules. A simple mathematical treatment is proposed to explain the results of the kinetics. 相似文献
30.
Matthieu Legrand Benedetta De Berardinis Hanna K. Gaggin Laura Magrini Arianna Belcher Benedetta Zancla Alexandra Femia Mandy Simon Shweta Motiwala Rasika Sambhare Salvatore Di Somma Alexandre Mebazaa Vishal S. Vaidya James L. Januzzi Jr from the Global Research on Acute Conditions Team 《PloS one》2014,9(11)