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排序方式: 共有392条查询结果,搜索用时 15 毫秒
1.
Structural membrane lipids are known to contribute to the high ethanol resistance of Saccharomyces cerevisiae (2, 4, 17). By manipulating the yeast cellular sterol level by changing the carbon-to-nitrogen source ratio in the chemostat growth medium, high delta 5,7-sterol levels were found to increase the resistance of yeast populations to ethanol-induced death. The resistance of the erg2 (delta 8----delta 7-sterol isomerase) mutant to ethanol-induced death was generally comparable with that of the delta 5,7-sterol-synthesizing strain. In contrast, the sensitivity of anaerobic growth to inhibition by ethanol was higher in the erg2 mutant in comparison with the delta 5,7-sterol-synthesizing strains but a high level of those sterols increased the vulnerability of anaerobic growth to ethanol inhibition. 相似文献
2.
DnaB proteolysis in vivo regulates oligomerization and its localization at oriC in Bacillus subtilis
William H. Grainger Cristina Machón David J. Scott Panos Soultanas 《Nucleic acids research》2010,38(9):2851-2864
Initiation of bacterial DNA replication at oriC is mediated by primosomal proteins that act cooperatively to melt an AT-rich region where the replicative helicase is loaded prior to the assembly of the replication fork. In Bacillus subtilis, the dnaD, dnaB and dnaI genes are essential for initiation of DNA replication. We established that their mRNAs are maintained in fast growing asynchronous cultures. DnaB is truncated at its C-terminus in a growth phase-dependent manner. Proteolysis is confined to cytosolic, not to membrane-associated DnaB, and affects oligomerization. Truncated DnaB is depleted at the oriC relative to the native protein. We propose that DNA-induced oligomerization is essential for its action at oriC and proteolysis regulates its localization at oriC. We show that DnaB has two separate ssDNA-binding sites one located within residues 1–300 and another between residues 365–428, and a dsDNA-binding site within residues 365–428. Tetramerization of DnaB is mediated within residues 1–300, and DNA-dependent oligomerization within residues 365–428. Finally, we show that association of DnaB with the oriC is asymmetric and extensive. It encompasses an area from the middle of dnaA to the end of yaaA that includes the AT-rich region melted during the initiation stage of DNA replication. 相似文献
3.
A. Panos 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1940,12(12):295-298
Ohne Zusammenfassung 相似文献
4.
5.
Elisabetta Zappone Isabelle Dugast Panos Papadopoulos Kelly Theriault Veronique David Jean-Yves LeGall Kim Summers Lawrie Powell Jim Drysdale 《Human genetics》1991,86(6):557-561
Summary This paper addresses the question of whether abnormalities in ferritin expression in the iron storage disease hemochromatosis (HC) involve major deletions or alterations in regions containing the two ferritin H genes that lie near the disease locus on chromosome 6p. We present evidence from analyses of Southern blots that neither gene is deleted in hemochromatosis. We also describe a polymorphism in one of the genes that we have previously shown to be a processed pseudogene. This polymorphism does not correlate with the presence of HC. The PIC value for this polymorphism was calculated as 0.49. 相似文献
6.
Mechanism of inducer expulsion in Streptococcus pyogenes: a two-step process activated by ATP. 总被引:22,自引:13,他引:9 下载免费PDF全文
The mechanism of methyl-beta-D-thiogalactoside-phosphate (TMG-P) expulsion from Streptococcus pyogenes was studied. The expulsion elicited by glucose was not due to exchange vectorial transphosphorylation between the expelled TMG and the incoming glucose since more beta-galactoside was displaced than glucose taken up, and the stoichiometry between TMG and glucose transport was inconstant. Instead, two distinct and sequential reactions, intracellular dephosphorylation of TMG-P followed by efflux of free TMG, mediated the expulsion. This was shown by temporary accumulation of free TMG effected by competitive inhibition of its efflux and by the aid of arsenate, which arrested dephosphorylation of TMG-P but did not affect efflux of free TMG formed intracellularly before arsenate addition. The competitive inhibition of TMG efflux by its structural analogs suggests that a transport protein facilitates the expulsion. Iodoacetate or fluoride prevented TMG-P dephosphorylation and its expulsion. However, provision of ATP via the arginine deiminase pathway restored these activities in the presence of the glycolytic inhibitors and stimulated expulsion in their absence. Other amino acids tested did not promote this restoration, and canavanine or norvaline severely inhibited it. Arginine without glucose neither elicited the dephosphorylation nor evoked the expulsion of TMG-P. Ionophores or ATPase inhibitors did not prevent the expulsion as elicited by glucose or its restoration by arginine. The results suggest that activation of the dephosphorylation-expulsion mechanism occurs independently of a functional glycolytic pathway, requires ATP provision, and is possibly due to protein phosphorylation controlled by a yet unknown metabolite. The in vivo phosphorylation of a protein (approximate molecular weight - 10,000) under the conditions of expulsion was demonstrated. 相似文献
7.
Ferritin H gene polymorphism in idiopathic hemochromatosis 总被引:1,自引:1,他引:0
Véronique David Panos Papadopoulos Jacqueline Yaouanq Martine Blayau Laurent Abel Elizabetta Zappone Muriel Perichon Jim Drysdale Jean-Yves Le Gall Marcel Simon 《Human genetics》1989,82(2):123-126
Summary We have analysed karyotypes and DNA from three patients with aniridia (congenital absence of irises) and Wilms' tumour. All three had constitutional deletions from the short arm of chromosome 11. The minimum region of overlap of the deletion involves a small region of band 11p13 presumed to contain the genetic loci responsible for both phenotypic abnormalities. Using cells from these patients, somatic cell hybrids with transformed mouse cells have been prepared. Individual subclones retaining either the deletion-11 chromosome or the normal chromosome 11, in addition to a variety of other human chromosomes, have been identified. The relative position of these breakpoints have been determined and the panel of hybrids has been used to map randomly-isolated 11p13 DNA sequences. The characterisation of these deletions has provided a useful panel of hybrids for random mapping strategies designed to identify the Wilms' and aniridia genes. 相似文献
8.
Yoji Hara Panos Ioannou Anthi Drousiotou Goula Stylianidou Violetta Anastasiadou Kunihiko Suzuki 《Human genetics》1994,94(2):136-140
Sandhoff disease occurs in the Christian Maronite community in Cyprus, a community that established over a thousand years ago. Nowadays, this community comprises less than 1% of the whole population, and has been culturally and socially isolated. Cultured fibroblasts from a patient from this inbred group showed a -hexosaminidase subunit mRNA of apparently the normal size but of reduced quantity. A mutational analysis of cDNA obtained by polymerase chain reaction amplification of mRNA showed a deletion of A at nt 76 (counted from A of the initiation codon, ATG). The deletion results in a frame shift and a premature termination within 20 amino acids from the N-terminus of the normal mature enzyme protein. The patient was homozygous for the deletion. The 5-end of the gene showed many discrepancies from the previously published sequence. We consider that these differences are probably polymorphisms of little functional significance, because the patient's fibroblasts generate decreased but stable mRNA and because some of these base changes were also found in the genes from control fibroblasts. An extensive evaluation of the prevalence of this mutant allele in this community is being initiated. 相似文献
9.
The ATP-binding-cassette transmembrane transporters (ABC transporters)
known from vertebrates belong to four major subfamilies: (1) the P-
glycoproteins (Pgp); (2) the cystic fibrosis transmembrane conductance
regulators (CFTR); (3) the Tap proteins encoded with the major
histocompatibility complex of mammals; and (4) the peroxisomal membrane
proteins. Both Pgp and CFTR have a structure suggesting a past internal
gene duplication; a phylogenetic analysis indicated that these duplications
occurred independently, while an independent tandem gene duplication
occurred in the case of the Tap family. Both the Pgp and Tap proteins show
evidence of relationship to bacterial ABC transporters lacking internal
duplication, and both are significantly more closely related to the HlyB
and MsbA families of transporters from purple bacteria than they are to ABC
transporters from nonpurple bacteria. The simplest hypothesis to explain
this observation is that eukaryotic Pgp and Tap genes are descended from a
mitochondrial gene or genes that were subsequently translocated to the
nuclear genome. The Pgp genes of eukaryotes are characterized by a
remarkable degree of convergent evolution between the ATP-binding cassettes
of their N- terminal and C-terminal halves, whereas no such convergence is
seen between the two halves of CFTR genes or between the duplicated Tap
genes. Exon 13 of the CFTR gene, which encodes a putative regulatory domain
not found in other ABC transporters apart from CFTR, showed high levels of
both synonymous and nonsynonymous difference in comparisons among different
mammalian species, suggesting that this region is a mutational hot spot.
相似文献
10.