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961.
Read TD Peterson SN Tourasse N Baillie LW Paulsen IT Nelson KE Tettelin H Fouts DE Eisen JA Gill SR Holtzapple EK Okstad OA Helgason E Rilstone J Wu M Kolonay JF Beanan MJ Dodson RJ Brinkac LM Gwinn M DeBoy RT Madpu R Daugherty SC Durkin AS Haft DH Nelson WC Peterson JD Pop M Khouri HM Radune D Benton JL Mahamoud Y Jiang L Hance IR Weidman JF Berry KJ Plaut RD Wolf AM Watkins KL Nierman WC Hazen A Cline R Redmond C Thwaite JE White O Salzberg SL Thomason B Friedlander AM Koehler TM Hanna PC 《Nature》2003,423(6935):81-86
Bacillus anthracis is an endospore-forming bacterium that causes inhalational anthrax. Key virulence genes are found on plasmids (extra-chromosomal, circular, double-stranded DNA molecules) pXO1 (ref. 2) and pXO2 (ref. 3). To identify additional genes that might contribute to virulence, we analysed the complete sequence of the chromosome of B. anthracis Ames (about 5.23 megabases). We found several chromosomally encoded proteins that may contribute to pathogenicity--including haemolysins, phospholipases and iron acquisition functions--and identified numerous surface proteins that might be important targets for vaccines and drugs. Almost all these putative chromosomal virulence and surface proteins have homologues in Bacillus cereus, highlighting the similarity of B. anthracis to near-neighbours that are not associated with anthrax. By performing a comparative genome hybridization of 19 B. cereus and Bacillus thuringiensis strains against a B. anthracis DNA microarray, we confirmed the general similarity of chromosomal genes among this group of close relatives. However, we found that the gene sequences of pXO1 and pXO2 were more variable between strains, suggesting plasmid mobility in the group. The complete sequence of B. anthracis is a step towards a better understanding of anthrax pathogenesis. 相似文献
962.
The deep-sea clams Calyptogena nautilei and C. tsubasa, which live in the cold-seep area at a depth of 3570 m in the Nankai Trough, Japan, have abundant hemoglobins (Hbs) in erythrocytes, similar to other Calyptogena species. We determined the cDNA-derived amino acid sequences of Hbs from two Calyptogena species. C. tsubasa was found to contain two dimeric Hbs, Hb I consisting of 145 amino acid residues and Hb II with 137 residues, similar to known Hbs from C. soyoae and C. kaikoi. Sequence identity was over 90% among the orthologous chains of Calyptogena Hbs. On the other hand, surprisingly, C. nautilei contained two monomeric Hbs, Hb III containing 141 residues and Hb IV with 134 residues. In addition, Hbs III and IV showed only 33–42% sequence identity with Hbs I and II from other Calyptogena species. The distal (E7) histidine, one of the functionally important residues of the heme protein, is replaced by glutamine in all Hb chains of Calyptogena species. A phylogenetic analysis indicated that C. nautilei Hb III is closer to Hb I from other Calyptogena species. We suppose that a Hb gene was duplicated at least three times in an immediate ancestor of Calyptogena and, presumably depending on physiological conditions different Hb sets are being expressed: dimeric Hbs I and II in C. soyoae, C. kaikoi and C. tsubasa, and monomeric Hbs III and IV in C. nautilei.
Received 13 May 2003; received after revision 5 June 2003; accepted 12 June 2003 相似文献
963.
Increase in neuronal nitric oxide synthase content of the gastroduodenal tract of diabetic rats 总被引:3,自引:0,他引:3
Adeghate E al-Ramadi B Saleh AM Vijayarasathy C Ponery AS Arafat K Howarth FC El-Sharkawy T 《Cellular and molecular life sciences : CMLS》2003,60(6):1172-1179
This study examined the changes occurring in the pattern of distribution and expression of neuronal nitric oxide synthase (nNOS)-positive nerves in the gastroduodenal tract of streptozotocin-induced diabetic rats. The ganglion cells of the myenteric plexus of the gastric antrum of normal rats contain nNOS. We also observed nNOS-positive neurons and fibres in the myenteric plexus of the duodenum of normal rats. After the onset of diabetes, the number and intensity of staining of nNOS-positive nerve profiles in the gastric antrum and duodenum did not change significantly. However, Western blotting showed a significant increase in the expression of nNOS after the onset of diabetes. In conclusion, diabetes of 4 and 32 weeks duration induced an increase in the tissue content of nNOS in the gastroduodenum of rat. The increase in the level of nNOS in the gastroduodenum of diabetic rats may explain why impaired gastric emptying is common in patients with diabetes. 相似文献
964.
Targeting of the Akt/PKB kinase to the actin skeleton 总被引:2,自引:0,他引:2
Cenni V Sirri A Riccio M Lattanzi G Santi S de Pol A Maraldi NM Marmiroli S 《Cellular and molecular life sciences : CMLS》2003,60(12):2710-2720
Serine/threonine kinase Akt/PKB intracellular distribution undergoes rapid changes in response to agonists such as Platelet-derived growth factor (PDGF) or Insulin-like growth factor (IGF). The concept has recently emerged that Akt subcellular movements are facilitated by interaction with nonsubstrate ligands. Here we show that Akt is bound to the actin skeleton in in situ cytoskeletal matrix preparations from PDGF-treated Saos2 cells, suggesting an interaction between the two proteins. Indeed, by immunoprecipitation and subcellular fractioning, we demonstrate that endogenous Akt and actin physically interact. Using recombinant proteins in in vitro binding and overlay assays, we further demonstrate that Akt interacts with actin directly. Expression of Akt mutants strongly indicates that the N-terminal PH domain of Akt mediates this interaction. More important, we show that the partition between actin bound and unbound Akt is not constant, but is modulated by growth factor stimulation. In fact, PDGF treatment of serum-starved cells triggers an increase in the amount of Akt associated with the actin skeleton, concomitant with an increase in Akt phosphorylation. Conversely, expression of an Akt mutant in which both Ser473 and Thr308 have been mutated to alanine completely abrogates PDGF-induced binding. The small GTPases Rac1 and Cdc42 seem to facilitate actin binding, possibly increasing Akt phosphorylation.Received 10 September 2003; accepted 25 September 2003 相似文献
965.
Hermann H De Petrocellis L Bisogno T Schiano Moriello A Lutz B Di Marzo V 《Cellular and molecular life sciences : CMLS》2003,60(3):607-616
Cannabinoid CB1 receptors and vanilloid VR1 receptors are co-localized to some extent in sensory neurons of the spinal cord and dorsal root ganglia. In this study, we over-expressed both receptor types in human embryonic kidney (HEK)-293 cells and investigated the effect of the CB1 agonist HU-210 on the VR1-mediated increase in intracellular Ca2+ ([Ca2+]i), a well-known response of the prototypical VR1 agonist capsaicin. After a 5-min pre-treatment, HU-210 (0.1 microM) significantly enhanced the effect of several concentrations of capsaicin on [Ca2+]i in HEK-293 cells over-expressing both rat CB1 and human VR1 (CB1-VR1-HEK cells), but not in cells over-expressing only human VR1 (VR1-HEK cells). This effect was blocked by the CB1 receptor antagonist SR141716A (0.5 microM), and by phosphoinositide-3-kinase and phospholipase C inhibitors. The endogenous agonist of CB1 and VR1 receptors, anandamide, was more efficacious in inducing a VR1-mediated stimulation of [Ca2+]i in CB1-VR1-HEK cells than in VR1-HEK cells, and part of its effect on the former cells was blocked by SR141716A (0.5 microM). Pre-treatment of CB1-VR1-HEK cells with forskolin, an adenylate cyclase activator, enhanced the capsaicin effect on [Ca2+]i. HU-210, which in the same cells inhibits forskolin-induced enhancement of cAMP levels, blocked the stimulatory effect of forskolin on capsaicin. Our data suggest that in cells co-expressing both CB1 and VR1 receptors, pre-treatment with CB1 agonists inhibits or stimulates VR1 gating by capsaicin depending on whether or not cAMP-mediated signalling has been concomitantly activated. 相似文献
966.
967.
Rawat UB Zavialov AV Sengupta J Valle M Grassucci RA Linde J Vestergaard B Ehrenberg M Frank J 《Nature》2003,421(6918):87-90
Protein synthesis takes place on the ribosome, where genetic information carried by messenger RNA is translated into a sequence of amino acids. This process is terminated when a stop codon moves into the ribosomal decoding centre (DC) and is recognized by a class-1 release factor (RF). RFs have a conserved GGQ amino-acid motif, which is crucial for peptide release and is believed to interact directly with the peptidyl-transferase centre (PTC) of the 50S ribosomal subunit. Another conserved motif of RFs (SPF in RF2) has been proposed to interact directly with stop codons in the DC of the 30S subunit. The distance between the DC and PTC is approximately 73 A. However, in the X-ray structure of RF2, SPF and GGQ are only 23 A apart, indicating that they cannot be at DC and PTC simultaneously. Here we show that RF2 is in an open conformation when bound to the ribosome, allowing GGQ to reach the PTC while still allowing SPF-stop-codon interaction. The results indicate new interpretations of accuracy in termination, and have implications for how the presence of a stop codon in the DC is signalled to PTC. 相似文献
968.
969.
An epi-allelic series of p53 hypomorphs created by stable RNAi produces distinct tumor phenotypes in vivo 总被引:45,自引:0,他引:45
Hemann MT Fridman JS Zilfou JT Hernando E Paddison PJ Cordon-Cardo C Hannon GJ Lowe SW 《Nature genetics》2003,33(3):396-400
The application of RNA interference (RNAi) to mammalian systems has the potential to revolutionize genetics and produce novel therapies. Here we investigate whether RNAi applied to a well-characterized gene can stably suppress gene expression in hematopoietic stem cells and produce detectable phenotypes in mice. Deletion of the Trp53 tumor suppressor gene greatly accelerates Myc-induced lymphomagenesis, resulting in highly disseminated disease. To determine whether RNAi suppression of Trp53 could produce a similar phenotype, we introduced several Trp53 short hairpin RNAs (shRNAs) into hematopoietic stem cells derived from E(mu)-Myc transgenic mice, and monitored tumor onset and overall pathology in lethally irradiated recipients. Different Trp53 shRNAs produced distinct phenotypes in vivo, ranging from benign lymphoid hyperplasias to highly disseminated lymphomas that paralleled Trp53-/- lymphomagenesis in the E(mu)-Myc mouse. In all cases, the severity and type of disease correlated with the extent to which specific shRNAs inhibited p53 activity. Therefore, RNAi can stably suppress gene expression in stem cells and reconstituted organs derived from those cells. In addition, intrinsic differences between individual shRNA expression vectors targeting the same gene can be used to create an 'epi-allelic series' for dissecting gene function in vivo. 相似文献
970.
Ru2 and Ru encode mouse orthologs of the genes mutated in human Hermansky-Pudlak syndrome types 5 and 6 总被引:12,自引:0,他引:12
Zhang Q Zhao B Li W Oiso N Novak EK Rusiniak ME Gautam R Chintala S O'Brien EP Zhang Y Roe BA Elliott RW Eicher EM Liang P Kratz C Legius E Spritz RA O'Sullivan TN Copeland NG Jenkins NA Swank RT 《Nature genetics》2003,33(2):145-153
Hermansky-Pudlak syndrome (HPS) is a genetically heterogeneous disease involving abnormalities of melanosomes, platelet dense granules and lysosomes. Here we have used positional candidate and transgenic rescue approaches to identify the genes mutated in ruby-eye 2 and ruby-eye mice (ru2 and ru, respectively), two 'mimic' mouse models of HPS. We also show that these genes are orthologs of the genes mutated in individuals with HPS types 5 and 6, respectively, and that their protein products directly interact. Both genes are previously unknown and are found only in higher eukaryotes, and together represent a new class of genes that have evolved in higher organisms to govern the synthesis of highly specialized lysosome-related organelles. 相似文献