E. coli a-hemolysin: a membrane-active protein toxin
Autor(a) principal: | |
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Data de Publicação: | 1998 |
Outros Autores: | |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Brazilian Journal of Medical and Biological Research |
Texto Completo: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000800002 |
Resumo: | Alpha-Hemolysin is synthesized as a 1024-amino acid polypeptide, then intracellularly activated by specific fatty acylation. A second activation step takes place in the extracellular medium through binding of Ca2+ ions. Even in the absence of fatty acids and Ca2+ HlyA is an amphipathic protein, with a tendency to self-aggregation. However, Ca2+-binding appears to expose hydrophobic patches on the protein surface, facilitating both self-aggregation and irreversible insertion into membranes. The protein may somehow bind membranes in the absence of divalent cations, but only when Ca2+ (or Sr2+, or Ba2+) is bound to the toxin in aqueous suspensions, i.e., prior to its interaction with bilayers, can <FONT FACE="Symbol">a</FONT>-hemolysin bind irreversibly model or cell membranes in such a way that the integrity of the membrane barrier is lost, and cell or vesicle leakage ensues. Leakage is not due to the formation of proteinaceous pores, but rather to the transient disruption of the bilayer, due to the protein insertion into the outer membrane monolayer, and subsequent perturbations in the bilayer lateral tension. Protein or glycoprotein receptors for <FONT FACE="Symbol">a</FONT>-hemolysin may exist on the cell surface, but the toxin is also active on pure lipid bilayers. |
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E. coli a-hemolysin: a membrane-active protein toxinalpha-hemolysinbacterial toxinsRTX toxinslipid-protein interactionscalcium-binding proteinsmodel membranesAlpha-Hemolysin is synthesized as a 1024-amino acid polypeptide, then intracellularly activated by specific fatty acylation. A second activation step takes place in the extracellular medium through binding of Ca2+ ions. Even in the absence of fatty acids and Ca2+ HlyA is an amphipathic protein, with a tendency to self-aggregation. However, Ca2+-binding appears to expose hydrophobic patches on the protein surface, facilitating both self-aggregation and irreversible insertion into membranes. The protein may somehow bind membranes in the absence of divalent cations, but only when Ca2+ (or Sr2+, or Ba2+) is bound to the toxin in aqueous suspensions, i.e., prior to its interaction with bilayers, can <FONT FACE="Symbol">a</FONT>-hemolysin bind irreversibly model or cell membranes in such a way that the integrity of the membrane barrier is lost, and cell or vesicle leakage ensues. Leakage is not due to the formation of proteinaceous pores, but rather to the transient disruption of the bilayer, due to the protein insertion into the outer membrane monolayer, and subsequent perturbations in the bilayer lateral tension. Protein or glycoprotein receptors for <FONT FACE="Symbol">a</FONT>-hemolysin may exist on the cell surface, but the toxin is also active on pure lipid bilayers.Associação Brasileira de Divulgação Científica1998-08-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000800002Brazilian Journal of Medical and Biological Research v.31 n.8 1998reponame:Brazilian Journal of Medical and Biological Researchinstname:Associação Brasileira de Divulgação Científica (ABDC)instacron:ABDC10.1590/S0100-879X1998000800002info:eu-repo/semantics/openAccessGoñi,F.M.Ostolaza,H.eng1998-09-21T00:00:00Zoai:scielo:S0100-879X1998000800002Revistahttps://www.bjournal.org/https://old.scielo.br/oai/scielo-oai.phpbjournal@terra.com.br||bjournal@terra.com.br1414-431X0100-879Xopendoar:1998-09-21T00:00Brazilian Journal of Medical and Biological Research - Associação Brasileira de Divulgação Científica (ABDC)false |
dc.title.none.fl_str_mv |
E. coli a-hemolysin: a membrane-active protein toxin |
title |
E. coli a-hemolysin: a membrane-active protein toxin |
spellingShingle |
E. coli a-hemolysin: a membrane-active protein toxin Goñi,F.M. alpha-hemolysin bacterial toxins RTX toxins lipid-protein interactions calcium-binding proteins model membranes |
title_short |
E. coli a-hemolysin: a membrane-active protein toxin |
title_full |
E. coli a-hemolysin: a membrane-active protein toxin |
title_fullStr |
E. coli a-hemolysin: a membrane-active protein toxin |
title_full_unstemmed |
E. coli a-hemolysin: a membrane-active protein toxin |
title_sort |
E. coli a-hemolysin: a membrane-active protein toxin |
author |
Goñi,F.M. |
author_facet |
Goñi,F.M. Ostolaza,H. |
author_role |
author |
author2 |
Ostolaza,H. |
author2_role |
author |
dc.contributor.author.fl_str_mv |
Goñi,F.M. Ostolaza,H. |
dc.subject.por.fl_str_mv |
alpha-hemolysin bacterial toxins RTX toxins lipid-protein interactions calcium-binding proteins model membranes |
topic |
alpha-hemolysin bacterial toxins RTX toxins lipid-protein interactions calcium-binding proteins model membranes |
description |
Alpha-Hemolysin is synthesized as a 1024-amino acid polypeptide, then intracellularly activated by specific fatty acylation. A second activation step takes place in the extracellular medium through binding of Ca2+ ions. Even in the absence of fatty acids and Ca2+ HlyA is an amphipathic protein, with a tendency to self-aggregation. However, Ca2+-binding appears to expose hydrophobic patches on the protein surface, facilitating both self-aggregation and irreversible insertion into membranes. The protein may somehow bind membranes in the absence of divalent cations, but only when Ca2+ (or Sr2+, or Ba2+) is bound to the toxin in aqueous suspensions, i.e., prior to its interaction with bilayers, can <FONT FACE="Symbol">a</FONT>-hemolysin bind irreversibly model or cell membranes in such a way that the integrity of the membrane barrier is lost, and cell or vesicle leakage ensues. Leakage is not due to the formation of proteinaceous pores, but rather to the transient disruption of the bilayer, due to the protein insertion into the outer membrane monolayer, and subsequent perturbations in the bilayer lateral tension. Protein or glycoprotein receptors for <FONT FACE="Symbol">a</FONT>-hemolysin may exist on the cell surface, but the toxin is also active on pure lipid bilayers. |
publishDate |
1998 |
dc.date.none.fl_str_mv |
1998-08-01 |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000800002 |
url |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000800002 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
10.1590/S0100-879X1998000800002 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
text/html |
dc.publisher.none.fl_str_mv |
Associação Brasileira de Divulgação Científica |
publisher.none.fl_str_mv |
Associação Brasileira de Divulgação Científica |
dc.source.none.fl_str_mv |
Brazilian Journal of Medical and Biological Research v.31 n.8 1998 reponame:Brazilian Journal of Medical and Biological Research instname:Associação Brasileira de Divulgação Científica (ABDC) instacron:ABDC |
instname_str |
Associação Brasileira de Divulgação Científica (ABDC) |
instacron_str |
ABDC |
institution |
ABDC |
reponame_str |
Brazilian Journal of Medical and Biological Research |
collection |
Brazilian Journal of Medical and Biological Research |
repository.name.fl_str_mv |
Brazilian Journal of Medical and Biological Research - Associação Brasileira de Divulgação Científica (ABDC) |
repository.mail.fl_str_mv |
bjournal@terra.com.br||bjournal@terra.com.br |
_version_ |
1754302929322377216 |