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991.
Cerantola V Vionnet C Aebischer OF Jenny T Knudsen J Conzelmann A 《The Biochemical journal》2007,401(1):205-216
Synthesis of VLCFAs (very long chain fatty acids) and biosynthesis of DHS (dihydrosphingosine) both are of vital importance for Saccharomyces cerevisiae. The bulk of VLCFAs and DHS are used for ceramide synthesis by the Lag1p (longevity-assurance gene 1)/Lac1p (longevity-assurance gene cognate 1)/Lip1p (Lag1p/Lac1p interacting protein) ceramide synthase. LAG1 and LAC1 are redundant but LIP1 is essential. Here we show that 4Delta (lag1Deltalac1Deltaypc1Deltaydc1Delta) cells devoid of all known endogenous ceramide synthesis pathways are unviable but can be rescued by the expression of Lass5, a mouse LAG1 homologue. Ceramide synthase activity of 4Delta.Lass5 cells only utilizes C16 and C18 fatty acids and does not require the help of Lip1p, an essential cofactor of Lag1p/Lac1p. HPLC-electrospray ionization-MS/MS analysis demonstrated that in IPCs (inositolphosphorylceramides) of 4Delta.Lass5, the very long chain fatty acids (C26 and C24) account for <1% instead of the normal >97%. Notwithstanding, IPCs incorporated into glycosylphosphatidylinositol anchors of 4Delta.Lass5 show normal mobility on TLC and the ceramide- and raft-dependent traffic of Gas1p (glycophospholipid-anchored surface protein) from endoplasmic reticulum to Golgi remains almost normal. Moreover, the biosynthesis of C24:0 fatty acids remains essential. Thus, C(24:0) and dihydrosphingosine are both necessary for survival of yeast cells even if they utilize C16 and C18 fatty acids for sphingolipid biosynthesis. 相似文献
992.
Kurth I Thompson DA Rüther K Feathers KL Chrispell JD Schroth J McHenry CL Schweizer M Skosyrski S Gal A Hübner CA 《Molecular and cellular biology》2007,27(4):1370-1379
RDH12 codes for a member of the family of short-chain alcohol dehydrogenases/reductases proposed to function in the visual cycle that supplies the chromophore 11-cis retinal to photoreceptor cells. Mutations in RDH12 cause severe and progressive childhood onset autosomal-recessive retinal dystrophy, including Leber congenital amaurosis. We generated Rdh12 knockout mice, which exhibited grossly normal retinal histology at 10 months of age. Levels of all-trans and 11-cis retinoids in dark- and light-adapted animals and scotopic and photopic electroretinogram (ERG) responses were similar to those for the wild type, as was recovery of the ERG response following bleaching, for animals matched for an Rpe65 polymorphism (p.L450M). Lipid peroxidation products and other measures of oxidative stress did not appear to be elevated in Rdh12(-/-) animals. RDH12 was localized to photoreceptor inner segments and the outer nuclear layer in both mouse and human retinas by immunohistochemistry. The present findings, together with those of earlier studies showing only minor functional deficits in mice deficient for Rdh5, Rdh8, or Rdh11, suggest that the activity of any one isoform is not rate limiting in the visual response. 相似文献
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An unusual propionigenic bacterium was isolated from the intestinal tract of the soil-feeding termite Thoracotermes macrothorax. Strain TmPN3 is a motile, long rod that stains gram-positive, but reacts gram-negative in the KOH test. It forms terminal
endospores and ferments lactate, glucose, lactose, fructose, and pyruvate to propionate and acetate via the methyl-malonyl-CoA
pathway. Propionate and acetate are formed at a ratio of 2:1, typical of most propionigenic bacteria. Under a H2/CO2 atmosphere, the fermentation product pattern of glucose, fructose, and pyruvate shifts towards propionate formation at the
expense of acetate. Cell suspensions reduce oxygen with lactate, glucose, glycerol, or hydrogen as electron donor. In the
presence of oxygen, the product pattern of lactate fermentation shifts from propionate to acetate production. 16S rRNA gene
sequence analysis showed that strain TmPN3 is a firmicute that clusters among the Acidaminococcaceae, a subgroup of the Clostridiales
comprising obligately anaerobic, often endospore-forming bacteria that possess an outer membrane. Based on phenotypic differences
and less than 92% sequence similarity to the 16S rRNA gene sequence of its closest relative, the termite hindgut isolate Acetonema longum, strain TmPN3T is proposed as the type species of a new genus, Sporotalea
propionica gen. nov. sp. nov. (DSM 13327T, ATCC BAA-626T). 相似文献
996.
RNAmmer: consistent and rapid annotation of ribosomal RNA genes 总被引:7,自引:0,他引:7
Lagesen K Hallin P Rødland EA Staerfeldt HH Rognes T Ussery DW 《Nucleic acids research》2007,35(9):3100-3108
The publication of a complete genome sequence is usually accompanied by annotations of its genes. In contrast to protein coding genes, genes for ribosomal RNA (rRNA) are often poorly or inconsistently annotated. This makes comparative studies based on rRNA genes difficult. We have therefore created computational predictors for the major rRNA species from all kingdoms of life and compiled them into a program called RNAmmer. The program uses hidden Markov models trained on data from the 5S ribosomal RNA database and the European ribosomal RNA database project. A pre-screening step makes the method fast with little loss of sensitivity, enabling the analysis of a complete bacterial genome in less than a minute. Results from running RNAmmer on a large set of genomes indicate that the location of rRNAs can be predicted with a very high level of accuracy. Novel, unannotated rRNAs are also predicted in many genomes. The software as well as the genome analysis results are available at the CBS web server. 相似文献
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