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Titolo:
Structural and functional studies of alpha-helix 5 region from Bacillus thuringiensis Cry1Ab delta-endotoxin
Autore:
Nunez-Valdez, ME; Sanchez, J; Lina, L; Guereca, L; Bravo, A;
Indirizzi:
Univ Nacl Autonoma Mexico, Inst Biotecnol, Dept Microbiol, Cuernavaca 62250, Morelos, Mexico Univ Nacl Autonoma Mexico Cuernavaca Morelos Mexico 62250 Morelos, Mexico
Titolo Testata:
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEIN STRUCTURE AND MOLECULAR ENZYMOLOGY
fascicolo: 1, volume: 1546, anno: 2001,
pagine: 122 - 131
SICI:
0167-4838(20010309)1546:1<122:SAFSOA>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
BRUSH-BORDER MEMBRANE; INSECTICIDAL CRYSTAL PROTEINS; PLANAR LIPID BILAYERS; MANDUCA-SEXTA; DOMAIN-III; IRREVERSIBLE BINDING; AMINOPEPTIDASE-N; LARVAL MIDGUT; PROTOXIN GENE; TOXIN;
Keywords:
delta-endotoxin; mode of action; oligomerization; Bacillus thuringiensis;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
42
Recensione:
Indirizzi per estratti:
Indirizzo: Bravo, A Univ Nacl Autonoma Mexico, Inst Biotecnol, Dept Microbiol, Ap Postal 510-3, Cuernavaca 62250, Morelos, Mexico Univ Nacl Autonoma Mexico Ap Postal 510-3 Cuernavaca Morelos Mexico 62250
Citazione:
M.E. Nunez-Valdez et al., "Structural and functional studies of alpha-helix 5 region from Bacillus thuringiensis Cry1Ab delta-endotoxin", BBA-PROT ST, 1546(1), 2001, pp. 122-131

Abstract

The crystal insecticidal proteins from Bacillus thuringiensis are modular proteins comprised of three domains connected by single linkers. Domain I is a seven a-helix bundle, which has been involved in membrane insertion andpore formation activity. Site-directed mutagenesis has contributed to identify regions that might play an important role in the structure of the pore-forming domain within the membrane. There are several evidences that support that the hairpin alpha4-alpha5 inserts into the membrane in an antiparallel manner, while other helices lie on the membrane surface. We hypothesized that highly conserved residues of alpha5 could play an important role in toxin insertion, oligomerization and/or pore formation. A total of 15 Cry1Ab mutants located in six conserved residues of Cry1Ab, Y153, Y161, H168, R173, W182 and G183, were isolated. Eleven mutants were located within helix a5, one mutant was located in the loop a4-a5 and three mutants, W182P, W182I and Gl83C, were located in the loop alpha5-alpha6. Their effect on binding, K+ permeability and toxicity against Manduca sexta larvae was analyzed and compared. The results provide direct evidence that some residues locatedwithin a5 have an important role in stability of the toxin within the insect gut, while some others also have an important role in pore formation. The results also provide evidence that conserved residues within helix a5 arenot involved in oligomer formation since mutations in these residues are able to make pores in vitro. (C) 2001 Published by Elsevier Science B.V.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/07/20 alle ore 00:04:38