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241.
Carneiro FA Lapido-Loureiro PA Cordo SM Stauffer F Weissmüller G Bianconi ML Juliano MA Juliano L Bisch PM Da Poian AT Poian AT 《European biophysics journal : EBJ》2006,35(2):145-154
The entry of enveloped animal viruses into their host cells always depends on membrane fusion triggered by conformational
changes in viral envelope glycoproteins. Vesicular stomatitis virus (VSV) infection is mediated by virus spike glycoprotein
G, which induces membrane fusion between the viral envelope and the endosomal membrane at the acidic environment of this compartment.
In this work, we evaluated VSV interactions with membranes of different phospholipid compositions, at neutral and acidic pH,
using atomic force microscopy (AFM) operating in the force spectroscopy mode, isothermal calorimetry (ITC) and molecular dynamics
simulation. We found that the binding forces differed dramatically depending on the membrane phospholipid composition, revealing
a high specificity of G protein binding to membranes containing phosphatidylserine (PS). In a previous work, we showed that
the sequence corresponding amino acid 164 of VSV G protein was as efficient as the virus in catalyzing membrane fusion at
pH 6.0. Here, we used this sequence to explore VSV–PS interaction using ITC. We found that peptide binding to membranes was
exothermic, suggesting the participation of electrostatic interactions. Peptide–membrane interaction at pH 7.5 was shown to
be specific to PS and dependent on the presence of His residues in the fusion peptide. The application of the simplified continuum
Gouy–Chapman theory to our system predicted a pH of 5.0 at membrane surface, suggesting that the His residues should be protonated
when located close to the membrane. Molecular dynamics simulations suggested that the peptide interacts with the lipid bilayer
through its N-terminal residues, especially Val145 and His148.
Fabiana A.Carneiro and Pedro A. Lapido-Loureiro contributed equally to this work
An erratum to this article can be found at 相似文献
242.
Recent studies have suggested that structural-based coloration is an honest signal of male genetic and/or conditional quality in sexual selection. However, whether structural coloration functions in intrasexual competition is unknown. We examined whether plumage color functions as a status signal during intrasexual interactions in the red-flanked bushrobin Tarsiger cyanurus; adult males have many blue plumes as structural coloration whereas yearling males and females are olive brown with few blue plumages. Blue males did not always dominate olive-brown males. The number of interactions did not differ with the colors of the two birds involved. The interactions of a blue male and an olive-brown male were less aggressive than those of two blue or of two olive-brown males. In this study, we found that structural plumage coloration may serve as a signal of aggressive intent and lower the escalation level of an aggressive interaction in a manner consistent with hypotheses regarding the evolution of delayed plumage maturation. 相似文献
243.
Baratto CM Dutra V Boldo JT Leiria LB Vainstein MH Schrank A 《Current microbiology》2006,53(3):217-221
Metarhizium anisopliae infects arthropods via a combination of specialized structures and cuticle degradation. Hydrolytic enzymes are accepted as key factors for the host penetration step and include chitinases. The characterization of the chi2 chitinase gene from M. anisopliae var. anisopliae is reported. The chi2 gene is interrupted by two short introns and is 1,542-bp long, coding a predicted protein of 419 amino acids with a stretch of 19 amino acid residues displaying characteristics of signal peptide. The predicted chitinase molecular mass is 44 kDa with a mature protein of 42 kDa and a theoretical pI of 4.8. The comparison of the CHI2 predicted protein to fungal orthologues revealed similarity to the glycohydrolase family 18 and a phylogenetic analysis was conducted. The chi2 gene is up-regulated by chitin as a carbon source and in conditions of fungus autolysis, and is down-regulated by glucose. This regulation is consistent with the presence of putative CreA/Crel/Crr1 carbon catabolic repressor binding domains on the regulatory sequence. 相似文献
244.
Hashimoto M Morimoto M Saimoto H Shigemasa Y Yanagie H Eriguchi M Sato T 《Biotechnology letters》2006,28(11):815-821
Chitosan is a biodegradable and biocompatible polymer and is useful as a non-viral vector for gene delivery. In order to deliver
pDNA/chitosan complex into macrophages expressing a mannose receptor, mannose-modified chitosan (man-chitosan) was employed.
The cellular uptake of pDNA/man-chitosan complexes through mannose recognition was then observed. The pDNA/man-chitosan complexes
showed no significant cytotoxicity in mouse peritoneal macrophages, while pDNA/man-PEI complexes showed strong cytotoxicity.
The pDNA/man-chitosan complexes showed much higher transfection efficiency than pDNA/chitosan complexes in mouse peritoneal
macrophages. Observation with a confocal laser microscope suggested differences in the cellular uptake mechanism between pDNA/chitosan
complexes and pDNA/man-chitosan complexes. Mannose receptor-mediated gene transfer thus enhances the transfection efficiency
of pDNA/chitosan complexes. 相似文献
245.
Quantification of DNA methyltransferases Dnmt3a and Dnmt3a2, and Dnmt3L in isolated male gonocytes in day 16.5 embryos confirmed that not Dnmt3a but Dnmt3a2 and Dnmt3L were the major Dnmt3s. The expression level of Dnmt3L constituted 5- to 10-fold molar excess compared to that of Dnmt3a2. The stimulation property of the DNA methylation activity of Dnmt3a2 with Dnmt3L towards substrate DNA in naked or nucleosomes was similar to that of Dnmt3a. However, the DNA methylation activity of not Dnmt3a but Dnmt3a2 was severely inhibited at the physiological salt concentration. Interestingly, the activity of Dnmt3a2 was significantly detected in the presence of Dnmt3L even at the physiological salt concentration. This indicates that Dnmt3a2 functions only in the presence of Dnmt3L in male gonocytes, and may explain why Dnmt3L is required specifically in mouse gonocytes for DNA methylation. 相似文献
246.
Angelo PF Lima AR Alves FM Blaber SI Scarisbrick IA Blaber M Juliano L Juliano MA 《The Journal of biological chemistry》2006,281(6):3116-3126
Human kallikrein 6 (hK6) is abundantly expressed in the central nervous system and is implicated in demyelinating disease. This study provided biochemical data about the substrate specificity and activation of hK6 by glycosaminoglycans and by kosmotropic salts, which followed the Hofmeister series. The screening of fluorescence resonance energy transfer (FRET) peptide families derived from Abz-KLRSSKQ-EDDnp resulted in the finding that Abz-AFRFSQ-EDDnp (where Abz is ortho-aminobenzoic acid and EDDnp is N-[2,4-dinitrophenyl]ethylenediamine)) is the best synthetic substrate described so far for hK6 (kcat/Km 38,667 s(-1) mm(-1)). It is noteworthy that the AFRFS sequence was found as a motif in the amino-terminal domain of seven human ionotropic glutamate receptor subunits. We also examined the hK6 hydrolytic activity on FRET peptides derived from human myelin basic protein, precursor of the Abeta amyloid peptide, reactive center loop of alpha1-antichymotrypsin, plasminogen, and maturation and inactivation cleavage sites of hK6, which were described earlier as natural substrates for hK6. The best substrates were derived from myelin basic protein. The hK6 maturation cleavage site was poorly hydrolyzed, and no evidence was found to support a two-step self-activation process reported previously. Finally, we assayed FRET peptides derived from sequences that span the cleavage sites for activation of protease-activated receptors (PAR) 1-4, and only the substrate with the PAR 2 sequence was hydrolyzed. These results further supported the hypothesis that hK6 expressed in the central nervous system is involved in normal myelin turnover/demyelination processes, but it is unlikely to self-activate. This report also suggested the possible modulation of ionotropic glutamate receptors and activation of PAR 2 by hK6. 相似文献
247.
Matsuo Y Morimoto T Kuwano M Loh PC Oshima T Ogasawara N 《The Journal of biological chemistry》2006,281(12):8110-8117
Bacillus subtilis YlqF belongs to the Era/Obg subfamily of small GTP-binding proteins and is essential for bacterial growth. Here we report that YlqF participates in the late step of 50 S ribosomal subunit assembly. YlqF was co-fractionated with the 50 S subunit, depending on the presence of noncleavable GTP analog. Moreover, the GTPase activity of YlqF was stimulated specifically by the 50 S subunit in vitro. Dimethyl sulfate footprinting analysis disclosed that YlqF binds to a unique position in 23 S rRNA. Yeast two-hybrid data revealed interactions between YlqF and the B. subtilis L25 protein (Ctc). The interaction was confirmed by the pull-down assay of the purified proteins. Specifically, YlqF is positioned around the A-site and P-site on the 50 S subunit. Proteome analysis of the abnormal 50 S subunits that accumulated in YlqF-depleted cells showed that L16 and L27 proteins, located near the YlqF-binding domain, are missing. Our results collectively indicate that YlqF will organize the late step of 50 S ribosomal subunit assembly. 相似文献
248.
Yano M Nagai K Morimoto K Miyamoto H 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2006,144(2):254-262
Random sequencing of molecules from a cDNA library constructed from mantle mRNA of the pearl oyster Pinctada fucata was used to obtain information on organic matrix proteins in the shell. In the determined sequences, we identified 7 distinct cDNAs encoding similar glycine-rich domains. Complete sequence analysis of these cDNAs showed that the predicted sequences of the proteins, which we named shematrins, possessed similar domains comprising repeat sequences of two or more glycines, followed by a hydrophobic amino acid. In addition, in shematrin-1, -2 and -3, a repeat domain designated as XGnX (where X is a hydrophobic amino acid) was conserved. It is of further note that all the shematrin proteins have RKKKY, RRKKY or RRRKY as their C-terminal sequence. According to northern blot analysis, all shematrins are exclusively expressed in the mantle, and particularly in the edge region of the mantle; furthermore, peptide fragments similar to shematrin-1 and -2 were detected in the prismatic layer of shells by MALDI-TOF/TOF MS analysis. These findings suggest that many of shematrins are synthesized in the mantle edge and secreted into the prismatic layer of the shell, where the protein family is thought to provide a framework for calcification. 相似文献
249.
Morishita K Takeuchi H Morimoto N Shimamura T Kadota Y Tsuda M Taniguchi T Ukeda H Yamamoto T Sugiura T 《Microbiology and immunology》2012,56(4):262-272
We investigated the correlation between the SOD activity of Helicobacter pylori (H. pylori) and gastroduodenal diseases and the characteristics of strains exposed to oxidative stress. Two sequenced strains, 26695 and J99, and clinical isolates from 156 Japanese patients with gastroduodenal diseases such as gastric cancer (n= 59) and non-cancer (n= 97) were used. SOD activities of all 158 isolates were measured and were divided into three groups: high-SOD activity (>0.22, n= 2), moderate-SOD activity (0.15≦≦0.22, n= 16) and low-SOD activity (<0.15, n= 140). Expressions of H. pylori Fe-SOD were examined by western blotting with anti-H. pylori Fe-SOD antibody prepared inhouse, and the profiles of Fe-SOD activity were investigated by zymogram with activity staining in native-PAGE. The characteristics of strains from high-SOD and low-SOD groups were examined under oxidative stress by paraquat. The average of H. pylori SOD activity was significantly higher in the cancer group than in the non-cancer group (P < 0.05). However, irrespective of SOD activity level, the amount of Fe-SOD expressed was variable among individual strains. Zymogram revealed a single band in moderate-SOD and low-SOD strains, but multiple bands in high-SOD strains were observed. These bands were confirmed as H. pylori Fe-SOD. Under oxidative stress with paraquat, low-SOD strains were drastically eliminated without inducible SOD activity; however, high-SOD strains were still viable with increased SOD activity. This study is the first to exhibit the characteristics of high-SOD activity strains representing multiple bands in zymograms and the correlation between H. pylori SOD activity and gastric cancer. 相似文献
250.
Sakamoto S Putalun W Pongkitwitoon B Juengwatanatrakul T Shoyama Y Tanaka H Morimoto S 《Plant cell reports》2012,31(1):103-110
A single-chain variable fragment antibody (scFv) against plumbagin (PL) accumulated the PL production in the hairy roots of
Plumbago zeylanica. Recombinant Agrobacterium rhizogenes (ATCC 15834) containing an scFv gene against PL (PL-scFv) were obtained through triparental mating and transformed into P. zeylanica to induce PL-scFv protein in the hairy roots. Up to 40 μg recombinant PL-scFv were expressed per milligram of soluble protein
in transgenic P. zeylanica hairy root cultures. The mean PL content obtained from transgenic hairy roots (12.24 μg/100 mg dry weight) exhibited 2.2
times higher than those obtained from wild-type (5.48 μg/100 mg dry weight). The high correlation between the PL-scFv expression
level and PL content of the recombinant plants suggested that the PL biosynthesis pathway had been modulated by the expression
of PL-scFv protein in the hairy roots of P. zeylanica. 相似文献