Biochimica et biophysica acta最新文献_第6页

Sorting of lipoproteins to the outer membrane in E. coli. 大肠杆菌外膜脂蛋白的分选。

Biochimica et biophysica acta Pub Date : 2004-11-11

Hajime Tokuda, Shin-ichi Matsuyama

{"title":"Sorting of lipoproteins to the outer membrane in E. coli.","authors":"Hajime Tokuda, Shin-ichi Matsuyama","doi":"","DOIUrl":"","url":null,"abstract":"Escherichia coli lipoproteins are anchored to the periplasmic surface of the inner or outer membrane depending on the sorting signal. An ATP-binding cassette (ABC) transporter, LolCDE, releases outer membrane-specific lipoproteins from the inner membrane, causing the formation of a complex between the released lipoproteins and the periplasmic molecular chaperone LolA. When this complex interacts with outer membrane receptor LolB, the lipoproteins are transferred from LolA to LolB and then localized to the outer membrane. The structures of LolA and LolB are remarkably similar to each other. Both have a hydrophobic cavity consisting of an unclosed beta-barrel and an alpha-helical lid. Structural differences between the two proteins reveal the molecular mechanisms underlying the energy-independent transfer of lipoproteins from LolA to LolB. Strong inner membrane retention of lipoproteins occurs with Asp at position 2 and a few limited residues at position 3. The inner membrane retention signal functions as a Lol avoidance signal and inhibits the recognition of lipoproteins by LolCDE, thereby causing their retention in the inner membrane. The positive charge of phosphatidylethanolamine and the negative charge of Asp at position 2 are essential for Lol avoidance. The Lol avoidance signal is speculated to cause the formation of a tight lipoprotein-phosphatidylethanolamine complex that has five acyl chains and therefore cannot be recognized by LolCDE.","PeriodicalId":8811,"journal":{"name":"Biochimica et biophysica acta","volume":" ","pages":"IN1-9"},"PeriodicalIF":0.0,"publicationDate":"2004-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25093679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Different structural requirements for adenylate cyclase toxin interactions with erythrocyte and liposome membranes. 腺苷酸环化酶毒素与红细胞和脂质体膜相互作用的不同结构要求。

Biochimica et biophysica acta Pub Date : 2004-01-28

Jirí Masín, Ivo Konopásek, Jaroslava Svobodová, Peter Sebo

{"title":"Different structural requirements for adenylate cyclase toxin interactions with erythrocyte and liposome membranes.","authors":"Jirí Masín, Ivo Konopásek, Jaroslava Svobodová, Peter Sebo","doi":"","DOIUrl":"","url":null,"abstract":"The bifunctional Bordetella adenylate cyclase toxin-hemolysin (ACT) penetrates target cell membranes, forms cation-selective channels and subverts cellular signaling by catalyzing uncontrolled conversion of ATP to cAMP. While primarily targeting phagocytes expressing the alphaMbeta2 integrin (CD11b/CD18), the toxin can also penetrate mammalian erythrocytes lacking the receptor and membrane endocytosis. We sought here to analyze the membrane interactions of ACT in a liposome model. Insertion of ACT into liposome membranes required calcium and caused leakage of entrapped fluorescent probes due to liposome disruption, as indicated by similar release kinetics for the approximately 398 Da FITC probe and its approximately 4400 Da dextran conjugate. However, the non-acylated proACT, which does not penetrate cellular membranes, exhibited higher capacity to bind and lyze liposomes than the mature toxin, showing that the fatty-acyl modification was not required for penetration of ACT into the lipid bilayer. Individual deletions within the channel-forming, acylation and repeat domains of ACT abolished its capacity to disrupt both liposomes and erythrocytes. In contrast to erythrocyte binding, however, the liposome binding was only lost upon a simultaneous deletion of both the channel-forming and acylation domains, suggesting that the acylation domain was also involved in liposome penetration of ACT. Moreover, substitutions of glutamates 509 and 516 by lysines, which strongly enhanced the channel-forming and hemolytic activity of ACT, did not affect its capacity to disrupt liposomes. This shows that the mechanism of ACT action in cellular membranes is not fully reproduced in liposome membranes.","PeriodicalId":8811,"journal":{"name":"Biochimica et biophysica acta","volume":"1660 1-2","pages":"144-54"},"PeriodicalIF":0.0,"publicationDate":"2004-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24192677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Beta-lactoglobulin/polysaccharide interactions during in vitro gastric and pancreatic hydrolysis assessed in dialysis bags of different molecular weight cut-offs. 在不同分子量切断的透析袋中评估体外胃和胰腺水解过程中β -乳球蛋白/多糖的相互作用。

Biochimica et biophysica acta Pub Date : 2004-01-22

J Mouécoucou, C Villaume, C Sanchez, L Méjean

{"title":"Beta-lactoglobulin/polysaccharide interactions during in vitro gastric and pancreatic hydrolysis assessed in dialysis bags of different molecular weight cut-offs.","authors":"J Mouécoucou, C Villaume, C Sanchez, L Méjean","doi":"","DOIUrl":"","url":null,"abstract":"The effects of gum arabic, low methylated (LM) pectin or xylan at levels of 0 and 50 wt.% on beta-lactoglobulin (beta-lg) digestibility were studied as well as the interactions between the two macromolecules during in vitro hydrolysis. The proteolysis was performed in a system involving a two-step hydrolysis: either pepsin alone, or pepsin followed by a trypsin/chymotrypsin (T/C) mixture in dialysis bags with molecular weight cut-offs (MWCO) 1000 or 8000 Da. Digestibility was estimated by the N release and by a SDS-PAGE electrophoresis of retentates from the two dialysis bags after hydrolysis. Turbidimetric measurements monitored the structural evolution of mixtures during the two-step hydrolysis. Results showed that beta-lg was almost resistant to peptic digestion and that polysaccharides increased the N release despite a reduction of pepsin activity. This is due to the formation of electrostatic complexes between polysaccharides and beta-lg, which reduced beta-lg aggregation, increasing its solubility. The polysaccharides reduced significantly the beta-lg T/C digestibility as determined using a dialysis bag with a MWCO 1000 Da, without a modification of their enzymatic activities. No significant effect of polysaccharides on the beta-lg digestibility was detected using the dialysis bag with a MWCO 8000 Da. The electrophoresis pattern did not show differences in the profile of retentates in relation with the dialysis bag used. This suggests that non-specific interactions could occur during the second step of hydrolysis between polysaccharides and amino acids or peptides smaller than 8000 Da.","PeriodicalId":8811,"journal":{"name":"Biochimica et biophysica acta","volume":"1670 2","pages":"105-12"},"PeriodicalIF":0.0,"publicationDate":"2004-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24177383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

EUROMIT 6. Abstracts of the 6th European Meeting on Mitochondrial Pathology. 1-4 July 2004, Nijmegen, The Netherlands. EUROMIT 6。第六届欧洲线粒体病理学会议摘要，2004年7月1日至4日，荷兰奈梅亨。

Biochimica et biophysica acta Pub Date : 2004-01-01

引用次数: 0

Abstracts of the 13th European Bioenergetics Conference. 21-26 August 2004. Pisa, Italy. 第十三届欧洲生物能量学会议摘要。2004年8月21-26日。意大利比萨。

Biochimica et biophysica acta Pub Date : 2004-01-01

引用次数: 0

Physico-chemical and immunological properties and partial amino acid sequencing of a new metalloprotease: endoprotease Thr-N. 新型金属蛋白酶:内源性蛋白酶Thr-N的理化、免疫学特性及部分氨基酸序列分析。

Biochimica et biophysica acta Pub Date : 2003-09-08

Sébastien Niamké, Olivier Guionie, Laetitia Guével-David, Claire Moallic, Soumaila Dabonne, Jean-Pierre Sine, Bernard Colas

{"title":"Physico-chemical and immunological properties and partial amino acid sequencing of a new metalloprotease: endoprotease Thr-N.","authors":"Sébastien Niamké, Olivier Guionie, Laetitia Guével-David, Claire Moallic, Soumaila Dabonne, Jean-Pierre Sine, Bernard Colas","doi":"","DOIUrl":"","url":null,"abstract":"Previous studies have described the isolation of a new metalloprotease with a strict specificity for the amide bonds of peptide substrates having a threonine residue at the P1' position [Biochem. Biophys. Res. Commun. 256 (1999) 307]. The present work reports the physico-chemical properties of the enzyme which enable the optimal conditions for the digestion of proteins by the protease to be determined. At pH 8.2 and up to 37 degrees C, the enzyme possesses a good proteolytic activity and is stable for at least 12 h. The protease is sensitive to detergents and dithiol-reducing agents so that these chemicals must be eliminated after treatment of the protein substrate when this needs to be denatured and reduced before its hydrolysis by the enzyme. An increase in the enzymatic activity is observed in the presence of urea up to a 2.0 M concentration, beyond which the activity decreases. The enzyme can also be used in the presence of organic solvents such as acetonitrile, isopropanol or dioxane (10%, v/v) without loss of activity. Studies performed with antibodies raised against the purified endoprotease Thr-N indicated the absence of cross-immunoinactivation and cross-immunoprecipitation with all tested proteases. Also, no homology of sequence was found with the proteases indexed in the databases. Thus, our results show that endoprotease Thr-N not only represents an original protease by its unique specificity but also by its immunological and molecular properties.","PeriodicalId":8811,"journal":{"name":"Biochimica et biophysica acta","volume":"1623 1","pages":"21-8"},"PeriodicalIF":0.0,"publicationDate":"2003-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22562447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Lysophosphatidic acid induces alpha1B-adrenergic receptor phosphorylation through G beta gamma, phosphoinositide 3-kinase, protein kinase C and epidermal growth factor receptor transactivation. 溶血磷脂酸通过G β γ、磷酸肌肽3激酶、蛋白激酶C和表皮生长因子受体的转激活诱导α - 1b肾上腺素能受体磷酸化。

Biochimica et biophysica acta Pub Date : 2003-07-21

Patricia Casas-González, Alejandro Ruiz-Martínez, J Adolfo García-Sáinz

{"title":"Lysophosphatidic acid induces alpha1B-adrenergic receptor phosphorylation through G beta gamma, phosphoinositide 3-kinase, protein kinase C and epidermal growth factor receptor transactivation.","authors":"Patricia Casas-González, Alejandro Ruiz-Martínez, J Adolfo García-Sáinz","doi":"","DOIUrl":"","url":null,"abstract":"Lysophosphatidic acid (LPA) induces alpha(1B)-adrenoceptor phosphorylation through pertussis toxin-sensitive G proteins, phosphoinositide 3-kinase (PI3K) and protein kinase C (PKC). Here we showed that transfection of the carboxyl terminus of the beta-adrenergic receptor kinase (betaARK) or the Deltap85 mutant of PI3K markedly decreased the alpha(1B)-adrenoceptor phosphorylation induced by LPA without decreasing the receptor phosphorylations induced by active phorbol esters or noradrenaline. In addition, it was observed that inhibitors of epidermal growth factor (EGF) receptor kinase and of metalloproteinases and an anti-heparin binding-EGF antibody also diminish LPA-induced phosphorylation; such partial inhibitions were not additive, indicating that they occur through a common process. Our data indicate that stimulation of LPA receptors activates pertussis-toxin-sensitive G proteins. Dissociated Gbetagamma subunits initiate two processes: one of them involving activation of metalloproteinases, heparin binding-EGF shedding and transactivation of EGF receptors and another independent of these events. Both processes triggered PI3K activity, which lead to activation of PKC and this to alpha(1B)-adrenoceptor phosphorylation. This is the first demonstration of a role of EGF receptor transactivation in the phosphorylation of a G protein-coupled receptor.","PeriodicalId":8811,"journal":{"name":"Biochimica et biophysica acta","volume":"1633 2","pages":"75-83"},"PeriodicalIF":0.0,"publicationDate":"2003-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22498635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The effects of insertional mutations in comQ, comP, srfA, spo0H, spo0A and abrB genes on bacilysin biosynthesis in Bacillus subtilis. comQ、comP、srfA、spo0H、spo0A和abrB基因插入突变对枯草芽孢杆菌溶杆菌素生物合成的影响

Biochimica et biophysica acta Pub Date : 2003-04-15

Ayten Yazgan Karataş, Seçil Cetin, Gülay Ozcengiz

{"title":"The effects of insertional mutations in comQ, comP, srfA, spo0H, spo0A and abrB genes on bacilysin biosynthesis in Bacillus subtilis.","authors":"Ayten Yazgan Karataş, Seçil Cetin, Gülay Ozcengiz","doi":"","DOIUrl":"","url":null,"abstract":"In Bacillus subtilis, two extracellular signaling peptides, ComX pheromone and CSF (competence and sporulation factor), stimulate the development of genetic competence and surfaction biosynthesis in response to high cell density (quorum sensing) by regulating the activity of transcription factor ComA. We recently showed that biosynthesis of dipeptide antibiotic bacilysin is linked to ComA and PhrC(CSF) in a Spo0K(Opp)-dependent manner by constructing phrC-, comA- and oppA-disrupted mutants of B. subtilis. In the present study, another pathway of quorum-sensing global regulation, namely, ComQ/ComX was found to be essential for bacilysin biosynthesis. ComP function in this chain was dispensable, most probably because of the existence of an alternative mean of ComA activation. The disruption of srfA operon in the bacilysin producer resulted with the bacilysin-negative phenotype; thus, our study verified that the srfA operon functions directly in the production of bacilysin. The abrB mutation suppressed the bacilysin-negative phenotype of a spo0A mutant, whereas the same mutation in the wild-type strain resulted in a significant increase in the production of bacilysin. This indicated that abrB gene product negatively controls the transcription of the gene(s) involved in bacilysin formation.","PeriodicalId":8811,"journal":{"name":"Biochimica et biophysica acta","volume":"1626 1-3","pages":"51-6"},"PeriodicalIF":0.0,"publicationDate":"2003-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22343100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Proceedings of the 3rd International Symposium on Vitamin B6, PQQ, Carbonyl Catalysis and Quinoproteins. Southampton, United Kingdom, 14-19 April 2002. 第三届维生素B6、PQQ、羰基催化和藜蛋白国际研讨会论文集。2002年4月14日至19日，英国南安普敦。

Biochimica et biophysica acta Pub Date : 2003-04-11

引用次数: 0

Different degree of cooperativity in adult, embryonic and mutated mouse muscle nicotinic receptors. 成年、胚胎和突变小鼠肌肉烟碱受体的不同程度的协同作用。

Biochimica et biophysica acta Pub Date : 2003-03-21

J Krùsek, F Vyskocil

引用次数: 0