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161.
Sun X Essalmani R Susan-Resiga D Prat A Seidah NG 《The Journal of biological chemistry》2011,286(33):29063-29073
The basic amino acid-specific proprotein convertase 5/6 (PC5/6) is an essential secretory protease, as knock-out mice die at birth and exhibit multiple homeotic transformation defects, including impaired bone morphogenesis and lung structure. Some of the observed defects were attributed to impaired processing of the TGFβ-like growth differentiating factor 11 precursor (proGdf11). In this work we present evidence that the latent TGFβ-binding proteins 2 and 3 (LTBP-2 and -3) inhibit the extracellular processing of proGdf11 by PC5/6A. This is partly due to the binding of LTBPs in the endoplasmic reticulum to the zymogen proPC5/6A, thus allowing the complex to exit the endoplasmic reticulum and be sequestered as an inactive zymogen in the extracellular matrix but not at the cell surface. This results in lower levels of PC5/6A in the media, without affecting those of PACE4, Furin, or a soluble form of PC7. The secreted soluble protease-specific activity of PC5/6A or a variant lacking the C-terminal Cys-rich domain (PC5/6-ΔCRD) is significantly decreased when co-expressed with LTBPs in cells. A similar enzymatic inhibition seems to apply to PACE4 and Furin. In situ hybridization analyses revealed extensive co-localization of PC5/6 and LTBP-3 mRNAs in mice at embryonic day 15.5 and post partum day 1. In conclusion, this is the first time that a zymogen of the proprotein convertases was shown to exit the endoplasmic reticulum in the presence of LTBPs, representing a potential novel mechanism for the regulation of PC5/6A activity, e.g. in tissues such as bone and lung where LTBP-3 and PC5/6 co-localize. 相似文献
162.
Neospora caninum is a major cause of abortion in cattle worldwide. However, little information is available for Algeria. Accordingly, 799 cattle from 87 farms in the north and northeast of Algeria were enrolled in a seroepidemiological survey. An indirect fluorescence antibody test (IFAT) revealed a seroprevalence of 19.6%. The animals were divided into 3 groups according to their breed: imported European cattle, local breeds, and crossed animals (European × local). Seroprevalences were 16.0%, 34.3%, and 18.6% in groups 1, 2, and 3, respectively. A case control study was performed to investigate the link between global seropositivity to N. caninum and abortion risk in those cattle farms. There was a significant (P < 0.01) association between the seroprevalence against N. caninum and the occurrence of abortion in those farms (odds ratio [OR] = 12.03). This was also observed at the individual level (OR = 2.79). The analysis of results according to the breed revealed a significant association between seroprevalence and abortion in groups 1 and 3, but not for group 2, despite the fact that the highest seroprevalence was observed in group 2. Cerebral tissues from 5 aborted fetuses were available for histology and polymerase chain reaction (PCR). One sample was found positive both by histology and by PCR, 2 samples were positive by PCR only, and 2 samples were negative in both tests. 相似文献
163.
The chondramides are mixed non-ribosomal peptide/polyketide secondary metabolites produced by the myxobacterium Chondromyces crocatus Cm c5, which exhibit strong cytotoxic activity. On the basis of their striking structural similarity to the marine depsipeptides jaspamides, the chondramides have been assumed to incorporate a (R)-beta-tyrosine moiety, an expectation we confirm here. Thus, the recent sequencing of the chondramide biosynthetic gene cluster provided the opportunity to probe the shared origin of this unusual beta-amino acid. We demonstrate here that (R)-beta-tyrosine is produced directly from l-tyrosine by the aminomutase CmdF. Along with the tyrosine aminomutase SgcC4 from the C-1027 enediyne pathway, this enzyme belongs to a novel family of tyrosine aminomutases related to the ammonium lyase family of enzymes but exhibits opposite facial selectivity for the hydroxycinnamate intermediate. We also show that the adenylation (A) domain in the chondramide pathway, which activates the beta-tyrosine building block, exhibits the required preference for (R)-beta-tyrosine, further arguing against alternative origins for the moiety in the chondramides. Comparison to the (S)-beta-tyrosine specific A domain SgcC1 should enhance our understanding of the structural and stereochemical determinants guiding amino acid selection by non-ribosomal peptide synthetase multienzymes. 相似文献
164.
Hountondji FC Hanna R Cherry AJ Sabelis MW Agboton B Korie S 《Experimental & applied acarology》2007,41(3):153-168
Virulence of entomopathogens is often measured at the individual level using a single host individual or a group of host individuals.
To what extent these virulence assessments reflect the impact of an entomopathogen on their host in the field remains largely
untested, however. A methodology was developed to induce epizootics of the cassava green mite fungal pathogen Neozygites tanajoae under controlled conditions to evaluate population-level virulence of two (one Beninese and one Brazilian) isolates of the
entomopathogen—which had shown similar individual-level virulence but different field impacts. In unrepeated separate experiments
we inoculated mite-infested potted cassava plants with either 50 or 25 live mites (high and low inoculum) previously exposed
to spores of N. tanajoae and monitored the development of fungal infections for each isolate under the same conditions. Both isolates caused mite
infections and an associated decline in host mite populations relative to the control (without fungus) in all experiments,
but prevalence of the fungus varied with isolate and increased with inoculum density. Peak infection levels were 90% for the
Beninese isolate and 36% for the Brazilian isolate at high inoculum density, and respectively 17% and 25% at low inoculum
density. We also measured dispersal from inoculated plants and found that spore dispersal increased with host infection levels,
independent of host densities, whereas mite dispersal varied between isolates. These results demonstrate that epizootiology
of N. tanajoae can be studied under controlled conditions and suggest that virulence tests at the population level may help to better predict
performance of fungal isolates than individual-level tests. 相似文献
165.
166.
167.
Jollivet F Raposo G Dimitrov A Sougrat R Goud B Perez F 《Molecular biology of the cell》2007,18(11):4637-4647
The Golgi complex is characterized by its unique morphology of closely apposed flattened cisternae that persists despite the large quantity of lipids and proteins that transit bidirectionally. Whether such a structure is maintained through endoplasmic reticulum (ER)-based recycling and auto-organization or whether it depends on a permanent Golgi structure is strongly debated. To further study Golgi maintenance in interphase cells, we developed a method allowing for a drug-free inactivation of Golgi dynamics and function in living cells. After Golgi inactivation, a new Golgi-like structure, containing only certain Golgi markers and newly synthesized cargoes, was produced. However, this structure did not acquire a normal Golgi architecture and was unable to ensure a normal trafficking activity. This suggests an integrative model for Golgi maintenance in interphase where the ER is able to autonomously produce Golgi-like structures that need pre-existing Golgi complexes to be organized as morphologically normal and active Golgi elements. 相似文献
168.
Schneiker S Perlova O Kaiser O Gerth K Alici A Altmeyer MO Bartels D Bekel T Beyer S Bode E Bode HB Bolten CJ Choudhuri JV Doss S Elnakady YA Frank B Gaigalat L Goesmann A Groeger C Gross F Jelsbak L Jelsbak L Kalinowski J Kegler C Knauber T Konietzny S Kopp M Krause L Krug D Linke B Mahmud T Martinez-Arias R McHardy AC Merai M Meyer F Mormann S Muñoz-Dorado J Perez J Pradella S Rachid S Raddatz G Rosenau F Rückert C Sasse F Scharfe M Schuster SC Suen G Treuner-Lange A Velicer GJ Vorhölter FJ 《Nature biotechnology》2007,25(11):1281-1289
The genus Sorangium synthesizes approximately half of the secondary metabolites isolated from myxobacteria, including the anti-cancer metabolite epothilone. We report the complete genome sequence of the model Sorangium strain S. cellulosum So ce56, which produces several natural products and has morphological and physiological properties typical of the genus. The circular genome, comprising 13,033,779 base pairs, is the largest bacterial genome sequenced to date. No global synteny with the genome of Myxococcus xanthus is apparent, revealing an unanticipated level of divergence between these myxobacteria. A large percentage of the genome is devoted to regulation, particularly post-translational phosphorylation, which probably supports the strain's complex, social lifestyle. This regulatory network includes the highest number of eukaryotic protein kinase-like kinases discovered in any organism. Seventeen secondary metabolite loci are encoded in the genome, as well as many enzymes with potential utility in industry. 相似文献
169.
Gui‐Liang Xu Hui Sun Chao Luo Luis Estevez Minghao Zhuang Han Gao Rachid Amine Hao Wang Xiaoyi Zhang Cheng‐Jun Sun Yuzi Liu Yang Ren Steve M. Heald Chunsheng Wang Zonghai Chen Khalil Amine 《Liver Transplantation》2019,9(2)
Lithium/selenium‐sulfur batteries have recently received considerable attention due to their relatively high specific capacities and high electronic conductivity. Different from the traditional encapsulation strategy for suppressing the shuttle effect, an alternative approach to directly bypass polysulfide/polyselenide formation via rational solid‐electrolyte interphase (SEI) design is demonstrated. It is found that the robust SEI layer that in situ forms during charge/discharge via interplay between rational cathode design and optimal electrolytes could enable solid‐state (de)lithiation chemistry for selenium‐sulfur cathodes. Hence, Se‐doped S22.2Se/Ketjenblack cathodes can attain a high reversible capacity with minimal shuttle effects during long‐term and high rate cycling. Moreover, the underlying solid‐state (de)lithiation mechanism, as evidenced by in situ 7Li NMR and in operando synchrotron X‐ray probes, further extends the optimal sulfur confinement pore size to large mesopores and even macropores that have been long considered as inferior sulfur or selenium host materials, which play a crucial role in developing high volumetric energy density batteries. It is expected that the findings in this study will ignite more efforts to tailor the compositional/structure characteristics of the SEI layers and the related ionic transport across the interface by electrode structure, electrolyte solvent, and electrolyte additive screening. 相似文献
170.
Romain Parent David Durantel Thomas Lahlali Aurélie Sallé Marie-Laure Plissonnier Daniel DaCosta Gaëtan Lesca Fabien Zoulim Marie-Jeanne Marion Birke Bartosch 《Biochemical and biophysical research communications》2014