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Titolo:
Restoration of lectin activity to an inactive abrin B chain by substitution and mutation of the 2 gamma subdomain
Autore:
de Sousa, M; Roberts, LM; Lord, JM;
Indirizzi:
Univ Warwick, Dept Biol Sci, Coventry CV4 7AL, W Midlands, England Univ Warwick Coventry W Midlands England CV4 7AL 7AL, W Midlands, England
Titolo Testata:
EUROPEAN JOURNAL OF BIOCHEMISTRY
fascicolo: 2, volume: 260, anno: 1999,
pagine: 355 - 361
SICI:
0014-2956(199903)260:2<355:ROLATA>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
RICINUS-COMMUNIS AGGLUTININ; GALACTOSE-BINDING ABILITY; A-CHAIN; EXPRESSION; SEQUENCE; PROTEIN; CLONING; SYSTEM; GENE;
Keywords:
abrin; abrin B chain; lectin; mutagenesis; 2 gamma subdomain;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
26
Recensione:
Indirizzi per estratti:
Indirizzo: Lord, JM Univ Warwick, Dept Biol Sci, Coventry CV4 7AL, W Midlands, England Univ Warwick Coventry W Midlands England CV4 7AL dlands, England
Citazione:
M. de Sousa et al., "Restoration of lectin activity to an inactive abrin B chain by substitution and mutation of the 2 gamma subdomain", EUR J BIOCH, 260(2), 1999, pp. 355-361

Abstract

Abrin is a heterodimeric plant protein that occurs in several isoforms (abrin-a, abrin-b, abrin-c and abrin-d), whose B chains are believed to eitherhave (abrin-a and abrin-d) or lack (abrin-b and abrin-c) the ability to bind galactose. The 5' signal sequence and toxin B chain (ATB)-coding region were excised from a preproabrin cDNA [K. A. Wood J. M. Lord, E. J. Wawrzynczak, and M. Piatak (1991) Eur J. Biochem. 198, 723-732], tentatively identified as abrin-c, which was predicted to lack lectin activity, and fused in-frame to generate pre-ATE cDNA. Transcripts, synthesized in vitro from pre-ATE cloned into the transcription vector pSP64T, were expressed after microinjection into Xenopus oocytes. The recombinant ATE was shown, using a qualitative sugar-binding assay, to be devoid of lectin activity. Lectin activity could not be restored to this nonbinding ATE by replacing the 2 gamma subdomain with the corresponding galactose-binding 2 gamma subdomain from ricin B chain, but it was restored by replacement with the active galactose-binding 2 gamma subdomain from a different abrin isoform (abrin-a). The putative galactose-binding pocket of the nonbinding ATE 2 gamma subdomain contained a His residue at the position occupied by a residue with an aromatic side chain (Tyr or Trp) in functional 2 gamma subdomains. Mutationally converting this His to either Tyr or Trp restored lectin activity to the nonbinding ATE, emphasizing the contribution of an aromatic side chain in a functional 2 gamma subdomain galactose-binding site for members of this lectin family.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/11/20 alle ore 17:01:40