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91.
Abergel C Nitschke W Malarte G Bruschi M Claverie JM Giudici-Orticoni MT 《Structure (London, England : 1993)》2003,11(5):547-555
The study of electron transfer between the copper protein rusticyanin (RCy) and the c(4)-cytochrome CYC(41) of the acidophilic bacterium Acidithiobacillus ferrooxidans has evidenced a remarkable decrease of RCy's redox potential upon complex formation. The structure of the CYC(41) obtained at 2.2 A resolution highlighted a specific glutamate residue (E121) involved in zinc binding as potentially playing a central role in this effect, required for the electron transfer to occur. EPR and stopped-flow experiments confirmed the strong inhibitory effect of divalent cations on CYC(41):RCy complex formation. A docking analysis of the CYC(41) and RCy structure allows us to propose a detailed model for the complex-induced tuning of electron transfer in agreement with our experimental data, which could be representative of other copper proteins involved in electron transfer. 相似文献
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94.
Partial molecular characterization of two simian immunodeficiency viruses (SIV) from African colobids: SIVwrc from Western red colobus (Piliocolobus badius) and SIVolc from olive colobus (Procolobus verus) 下载免费PDF全文
Courgnaud V Formenty P Akoua-Koffi C Noe R Boesch C Delaporte E Peeters M 《Journal of virology》2003,77(1):744-748
In order to study primate lentivirus evolution in the Colobinae subfamily, in which only one simian immunodeficiency virus (SIV) has been described to date, we screened additional species from the three different genera of African colobus monkeys for SIV infection. Blood was obtained from 13 West African colobids, and HIV cross-reactive antibodies were observed in 5 of 10 Piliocolobus badius, 1 of 2 Procolobus verus, and 0 of 1 Colobus polykomos specimens. Phylogenetic analyses of partial pol sequences revealed that the new SIVs were more closely related to each other than to the other SIVs and especially did not cluster with the previously described SIVcol from Colobus guereza. This study presents evidence that the three genera of African colobus monkeys are naturally infected with an SIV and indicates also that there was no coevolution between virus and hosts at the level of the Colobinae subfamily. 相似文献
95.
Levraud JP Adam M Luciani MF de Chastellier C Blanton RL Golstein P 《The Journal of cell biology》2003,160(7):1105-1114
Cell death in the stalk of Dictyostelium discoideum, a prototypic vacuolar cell death, can be studied in vitro using cells differentiating as a monolayer. To identify early events, we examined potentially dying cells at a time when the classical signs of Dictyostelium cell death, such as heavy vacuolization and membrane lesions, were not yet apparent. We observed that most cells proceeded through a stereotyped series of differentiation stages, including the emergence of "paddle" cells showing high motility and strikingly marked subcellular compartmentalization with actin segregation. Paddle cell emergence and subsequent demise with paddle-to-round cell transition may be critical to the cell death process, as they were contemporary with irreversibility assessed through time-lapse videos and clonogenicity tests. Paddle cell demise was not related to formation of the cellulose shell because cells where the cellulose-synthase gene had been inactivated underwent death indistinguishable from that of parental cells. A major subcellular alteration at the paddle-to-round cell transition was the disappearance of F-actin. The Dictyostelium vacuolar cell death pathway thus does not require cellulose synthesis and includes early actin rearrangements (F-actin segregation, then depolymerization), contemporary with irreversibility, corresponding to the emergence and demise of highly polarized paddle cells. 相似文献
96.
Slowed conduction and thin myelination of peripheral nerves associated with mutant rho Guanine-nucleotide exchange factor 10 下载免费PDF全文
Verhoeven K De Jonghe P Van de Putte T Nelis E Zwijsen A Verpoorten N De Vriendt E Jacobs A Van Gerwen V Francis A Ceuterick C Huylebroeck D Timmerman V 《American journal of human genetics》2003,73(4):926-932
Slowed nerve-conduction velocities (NCVs) are a biological endophenotype in the majority of the hereditary motor and sensory neuropathies (HMSN). Here, we identified a family with autosomal dominant segregation of slowed NCVs without the clinical phenotype of HMSN. Peripheral-nerve biopsy showed predominantly thinly myelinated axons. We identified a locus at 8p23 and a Thr109Ile mutation in ARHGEF10, encoding a guanine-nucleotide exchange factor (GEF) for the Rho family of GTPase proteins (RhoGTPases). Rho GEFs are implicated in neural morphogenesis and connectivity and regulate the activity of small RhoGTPases by catalyzing the exchange of bound GDP by GTP. Expression analysis of ARHGEF10, by use of its mouse orthologue Gef10, showed that it is highly expressed in the peripheral nervous system. Our data support a role for ARHGEF10 in developmental myelination of peripheral nerves. 相似文献
97.
The chemical structure and interactions of the cell wall polysaccharides from the red edible seaweed Palmaria palmata were studied by liquid-like magic-angle-spinning (MAS) and cross-polarization MAS (CPMAS) solid-state 13C NMR spectroscopy. The liquid-like MAS and CPMAS 13C NMR spectra of the rehydrated algal powder revealed the presence of beta-(1-->4)/beta-(1-->3)-linked D-xylan with chemical shifts close to those observed in the solution 13C NMR spectrum of the polysaccharide. Observation of mix-linked xylan in the liquid-like MAS 13C NMR spectrum indicated that part of this cell wall polysaccharide is loosely held in the alga. The CPMAS NMR spectrum of the dry algal powder alcohol insoluble residue (AIR) showed broad peaks most of which corresponded to the mix-linked xylan. Hydration of AIR induced a marked increase in the signal resolution also in the CPMAS NMR spectra together with a shift of the C-3 and C-4 signals of the (1-->3)- and (1-->4)-linked xylose, respectively. Such modifications were present in the spectrum of hydrated (1-->3)-linked xylan from the green seaweed Caulerpa taxifolia and absent in that of (1-->4)-linked xylan from P. palmata. This result emphasizes the important role of (1-->3) linkages on the mix-linked xylan hydration-induced conformational rearrangement. The mix-linked xylan signals were observed in the CPMAS NMR spectrum of hydrated residues obtained after extensive extractions by NaOH or strong chaotropic solutions indicating strong hydrogen bonds or covalent linkages. T(1 rho) relaxations were measured close or above 10 ms for the mix-linked xylan in the dry and hydrated state in AIR and indicated that the overall xylan chains likely remain rigid. Rehydration of the mix-linked xylan lead to a decrease in the motion of protons bounded to the C-1 and C-4 carbons of the (1-->4)-linked xylose supporting the re-organization of the xylan chains under hydration involving junction-zones held by hydrogen bonds between adjacent (1-->4)-linked xylose blocks. The CPMAS NMR spectrum of both dry and rehydrated residues obtained after NaOH and HCl extractions demonstrated the presence of cellulose and (1-->4)-linked xylans. The structures of the different polysaccharides are discussed in relation to their interactions and putative functions on the cell wall mechanical properties in P. palmata. 相似文献
98.
The model B6(dom1) minor histocompatibility antigen is encoded by a mouse homolog of the yeast STT3 gene 总被引:1,自引:0,他引:1
McBride K Baron C Picard S Martin S Boismenu D Bell A Bergeron J Perreault C 《Immunogenetics》2002,54(8):562-569
The B6(dom1) minor histocompatibility antigen (MiHA) is a model antigen, since it is both the epitome of an immunodominant epitope and an ideal target for adoptive cancer immunotherapy. Based on DNA sequencing and MS/MS analyses, we report that B6(dom1) corresponds to amino acids 770-778 (KAPDNRETL) of a protein we propose to call SIMP (source of immunodominant MHC-associated peptides) that is encoded by a mouse homolog of the yeast STT3gene. STT3, a member of the oligosaccharyltransferase complex, is essential for cell proliferation. Phenotypic and genotypic analyses among eight strains of mice revealed a precise correlation between susceptibility or resistance to B6(dom1)-specific cytotoxic T lymphocytes (CTLs) and the presence of a Glu vs Asp amino acid at position 776 of the SIMP protein, respectively. Strikingly, while the difference in the amino acid sequence 770-778 encoded by the two SIMP alleles represents a very conservative substitution, these allelic peptides were not crossreactive at the CTL level, and both peptides were immunodominant when presented to mice homozygous for the opposite allele. In addition, we have cloned a human ortholog of SIMP whose predicted protein shares 97% amino acid identity with mouse SIMP. These results strengthen the concept that MHC class-I-associated MiHAs originate as a consequence of rare polymorphisms among highly conserved genes. Furthermore, the notion that a peptide differing from a self analog by a single methylene group can be immunodominant has implications regarding our understanding of the mechanisms of immunodominance. 相似文献
99.
Rigourd M Ehresmann C Parniak MA Ehresmann B Marquet R 《The Journal of biological chemistry》2002,277(21):18611-18618
100.
Omiya R Buteau C Kobayashi H Paya CV Celis E 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(4):2172-2179
Posttransplant lymphoproliferative disorder (PTLD) and B cell lymphomas induced by EBV continue to be a major life-threatening complication in transplant patients. The establishment and enhancement of T cell immunity to EBV before transplantation and immunosuppressive therapy could help diminish these complications, but the lack of an effective vaccine has limited this prophylactic approach. We describe here the identification of a peptide epitope from the EBV EBNA2 Ag that is capable of inducing in vitro CD4(+) T cell responses that inhibit the EBV-mediated B lymphocyte proliferation associated with PTLD. Most significantly, T cell responses to the EBNA2 epitope were found to be restricted by numerous MHC class II alleles (DR1, DR7, DR16, DR52, DQ2, and DQ7), indicating that this peptide is highly promiscuous and would be recognized by a large proportion (>50%) of the general population. These results are relevant for the design of a simple, inexpensive and widely applicable peptide-based vaccine to prevent PTLD in solid organ transplant patients. 相似文献