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951.
Cryptococcus neoformans senses CO2 through the carbonic anhydrase Can2 and the adenylyl cyclase Cac1
Mogensen EG Janbon G Chaloupka J Steegborn C Fu MS Moyrand F Klengel T Pearson DS Geeves MA Buck J Levin LR Mühlschlegel FA 《Eukaryotic cell》2006,5(1):103-111
Cryptococcus neoformans, a fungal pathogen of humans, causes fatal meningitis in immunocompromised patients. Its virulence is mainly determined by the elaboration of a polysaccharide capsule surrounding its cell wall. During its life, C. neoformans is confronted with and responds to dramatic variations in CO2 concentrations; one important morphological change triggered by the shift from its natural habitat (0.033% CO2) to infected hosts (5% CO2) is the induction of capsule biosynthesis. In cells, CO2 is hydrated to bicarbonate in a spontaneous reaction that is accelerated by carbonic anhydrases. Here we show that C. neoformans contains two beta-class carbonic anhydrases, Can1 and Can2. We further demonstrate that CAN2, but not CAN1, is abundantly expressed and essential for the growth of C. neoformans in its natural environment, where CO2 concentrations are limiting. Structural studies reveal that Can2 forms a homodimer in solution. Our data reveal Can2 to be the main carbonic anhydrase and suggest a physiological role for bicarbonate during C. neoformans growth. Bicarbonate directly activates the C. neoformans Cac1 adenylyl cyclase required for capsule synthesis. We show that this specific activation is optimal at physiological pH. 相似文献
952.
Functional metagenomic selection of ribulose 1, 5‐bisphosphate carboxylase/oxygenase from uncultivated bacteria 下载免费PDF全文
Vanessa A. Varaljay Sriram Satagopan Justin A. North Brian Witte Manuella N. Dourado Karthik Anantharaman Mark A. Arbing Shelley Hoeft McCann Ronald S. Oremland Jillian F. Banfield Kelly C. Wrighton F. Robert Tabita 《Environmental microbiology》2016,18(4):1187-1199
Ribulose 1,5‐bisphosphate carboxylase/oxygenase (RubisCO) is a critical yet severely inefficient enzyme that catalyses the fixation of virtually all of the carbon found on Earth. Here, we report a functional metagenomic selection that recovers physiologically active RubisCO molecules directly from uncultivated and largely unknown members of natural microbial communities. Selection is based on CO2‐dependent growth in a host strain capable of expressing environmental deoxyribonucleic acid (DNA), precluding the need for pure cultures or screening of recombinant clones for enzymatic activity. Seventeen functional RubisCO‐encoded sequences were selected using DNA extracted from soil and river autotrophic enrichments, a photosynthetic biofilm and a subsurface groundwater aquifer. Notably, three related form II RubisCOs were recovered which share high sequence similarity with metagenomic scaffolds from uncultivated members of the Gallionellaceae family. One of the Gallionellaceae RubisCOs was purified and shown to possess CO2/O2 specificity typical of form II enzymes. X‐ray crystallography determined that this enzyme is a hexamer, only the second form II multimer ever solved and the first RubisCO structure obtained from an uncultivated bacterium. Functional metagenomic selection leverages natural biological diversity and billions of years of evolution inherent in environmental communities, providing a new window into the discovery of CO2‐fixing enzymes not previously characterized. 相似文献
953.
Akın C Bilgin CC Beerli P Westaway R Ohst T Litvinchuk SN Uzzell T Bilgin M Hotz H Guex GD Plötner J 《Journal of Biogeography》2010,37(11):2111-2124
AIM: Our aims were to assess the phylogeographic patterns of genetic diversity in eastern Mediterranean water frogs and to estimate divergence times using different geological scenarios. We related divergence times to past geological events and discuss the relevance of our data for the systematics of eastern Mediterranean water frogs. LOCATION: The eastern Mediterranean region. METHODS: Genetic diversity and divergence were calculated using sequences of two protein-coding mitochondrial (mt) genes: ND2 (1038 bp, 119 sequences) and ND3 (340 bp, 612 sequences). Divergence times were estimated in a Bayesian framework under four geological scenarios representing alternative possible geological histories for the eastern Mediterranean. We then compared the different scenarios using Bayes factors and additional geological data. RESULTS: Extensive genetic diversity in mtDNA divides eastern Mediterranean water frogs into six main haplogroups (MHG). Three MHGs were identified on the Anatolian mainland; the most widespread MHG with the highest diversity is distributed from western Anatolia to the northern shore of the Caspian Sea, including the type locality of Pelophylax ridibundus. The other two Anatolian MHGs are restricted to south-eastern Turkey, occupying localities west and east of the Amanos mountain range. One of the remaining three MHGs is restricted to Cyprus; a second to the Levant; the third was found in the distribution area of European lake frogs (P. ridibundus group), including the Balkans. MAIN CONCLUSIONS: Based on geological evidence and estimates of genetic divergence we hypothesize that the water frogs of Cyprus have been isolated from the Anatolian mainland populations since the end of the Messinian salinity crisis (MSC), i.e. since c. 5.5-5.3 Ma, while our divergence time estimates indicate that the isolation of Crete from the mainland populations (Peloponnese, Anatolia) most likely pre-dates the MSC. The observed rates of divergence imply a time window of c. 1.6-1.1 million years for diversification of the largest Anatolian MHG; divergence between the two other Anatolian MHGs may have begun about 3.0 Ma, apparently as a result of uplift of the Amanos Mountains. Our mtDNA data suggest that the Anatolian water frogs and frogs from Cyprus represent several undescribed species. 相似文献
954.
955.
956.
Jason M. Butler Daniel J. Nolan Eva L. Vertes Barbara Varnum-Finney Hideki Kobayashi Andrea T. Hooper Marco Seandel Koji Shido Ian A. White Mariko Kobayashi Larry Witte Chad May Carrie Shawber Yuki Kimura Jan Kitajewski Zev Rosenwaks Irwin D. Bernstein Shahin Rafii 《Cell Stem Cell》2010,6(3):251-264
Highlights? Coculture with endothelial cells promotes HSC expansion and self-renewal ? Endothelial cell effect on HSCs mediated by Notch signaling ? In vivo, sinusoidal endothelial cells (SECs) express Notch ligands ? Blocking vessel remodeling impairs hematopoietic recovery after irradiation 相似文献
957.
Kerry Purtell Torsten K. Roepke Geoffrey W. Abbott 《The international journal of biochemistry & cell biology》2010,42(11):1767-1770
Inherited Long QT Syndrome (LQTS), a cardiac arrhythmia that predisposes to the often lethal ventricular fibrillation, is commonly linked to mutations in KCNQ1. The KCNQ1 voltage-gated K+ channel α subunit passes ventricular myocyte K+ current that helps bring a timely end to each heart-beat. KCNQ1, like many K+ channel α subunits, is regulated by KCNE β subunits, inherited mutations in which also associate with LQTS. KCNQ1 and KCNE mutations are also associated with atrial fibrillation. It has long been known that thyroid status strongly influences cardiac function, and that thyroid dysfunction causes abnormal cardiac structure and rhythm. We recently discovered that KCNQ1 and KCNE2 form a thyroid-stimulating hormone-stimulated K+ channel in the thyroid that is required for normal thyroid hormone biosynthesis. Here, we review this novel genetic link between cardiac and thyroid physiology and pathology, and its potential influence upon future therapeutic strategies in cardiac and thyroid disease. 相似文献
958.
The Gobioninae are a group of morphologically and ecologically diverse Eurasian freshwater cyprinid fishes. The intergeneric
relationships of this group are unresolved and the possible monophyly of this subfamily remains to be established. We used
complete mitochondrial cytochrome b gene sequences from most genera within the gobionine group, in addition to a selection of cyprinid outgroups, to investigate
the possible monophyly of this group and resolve the interrelationships within the group. Our results support the monophyly
of the Gobioninae and identify four monophyletic groups within the subfamily; the Hemibarbus group, the Sarcocheilichthys group, the Gobio group, and the Pseudogobio group. The morphologically aberrant genera Gobiobotia, Xenophysogobio and Gobiocypris are included in the Gobioninae, with the latter a sister group of Gnathopogon. 相似文献
959.
Glas J Seiderer J Tillack C Pfennig S Beigel F Jürgens M Olszak T Laubender RP Weidinger M Müller-Myhsok B Göke B Ochsenkühn T Lohse P Diegelmann J Czamara D Brand S 《PloS one》2010,5(12):e14466
Background
The aims were to analyze two novel NOD2 variants (rs2066843 and rs2076756) in a large cohort of patients with inflammatory bowel disease and to elucidate phenotypic consequences.Methodology/Principal Findings
Genomic DNA from 2700 Caucasians including 812 patients with Crohn''s disease (CD), 442 patients with ulcerative colitis (UC), and 1446 healthy controls was analyzed for the NOD2 SNPs rs2066843 and rs2076756 and the three main CD-associated NOD2 variants p.Arg702Trp (rs2066844), p.Gly908Arg (rs2066847), and p.Leu1007fsX1008 (rs2066847). Haplotype and genotype-phenotype analyses were performed. The SNPs rs2066843 (p = 3.01×10−5, OR 1.48, [95% CI 1.23-1.78]) and rs2076756 (p = 4.01×10−6; OR 1.54, [95% CI 1.28-1.86]) were significantly associated with CD but not with UC susceptibility. Haplotype analysis revealed a number of significant associations with CD susceptibility with omnibus p values <10−10. The SNPs rs2066843 and rs2076756 were in linkage disequilibrium with each other and with the three main CD-associated NOD2 mutations (D''>0.9). However, in CD, SNPs rs2066843 and rs2076756 were more frequently observed than the other three common NOD2 mutations (minor allele frequencies for rs2066843 and rs2076756: 0.390 and 0.380, respectively). In CD patients homozygous for these novel NOD2 variants, genotype-phenotype analysis revealed higher rates of a penetrating phenotype (rs2076756: p = 0.015) and fistulas (rs2076756: p = 0.015) and significant associations with CD-related surgery (rs2076756: p = 0.003; rs2066843: p = 0.015). However, in multivariate analysis only disease localization (p<2×10−16) and behaviour (p = 0.02) were significantly associated with the need for surgery.Conclusion/Significance
The NOD2 variants rs2066843 and rs2076756 are novel and common CD susceptibility gene variants. 相似文献960.