Mutants of common bean alpha-amylase inhibitor-2 as an approach to investigate binding specificity to alpha-amylases
| Autor: | Da Silva, M. C. M., Mello, L. V., Coutinho, M. V., Rigden, D. J., Neshich, G., Chrispeels, M. J., MARIA FATIMA GROSSI-DE-SA |
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| Jazyk: | angličtina |
| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA-Alice) Empresa Brasileira de Pesquisa Agropecuária (Embrapa) instacron:EMBRAPA Scopus-Elsevier |
| Popis: | Despite the presence of a family of defense proteins, Phaseolus vulgaris can be attacked by bruchid insects resulting in serious damage to stored grains. The two distinct active forms of a-amylase inhibitors, a-AI1 and a-AI2, in P. vulgaris show different specificity toward a-amylases. Zabrotes subfasciatus a-amylase is inhibited by a-AI2 but not by a-AI1. In contrast, porcine a-amylase is inhibited by a-AI1 but not by a-AI2. The objective of this work was to understand the molecular basis of the specificity of two inhibitors in P. vulgaris (a-AI1 and a-AI2) in relation to a-amylases. Mutants of a-AI2 were made and expressed in tobacco plants. The results showed that all the a-AI2 mutant inhibitors lost their activity against the insect a-amylases but none exhibited activity toward the mammalian a-amylase. The replacement of His33 of a-AI2 with the a-AI1-like sequence Ser-Tyr-Asn abolished inhibition of Z. subfasciatus a-amylase. From structural modeling, the conclusion is that the size and complexity of the amylase-inhibitor interface explain why mutation of the N-terminal loop and resultant abolition of Z. subfasciatus a-amylase inhibition are not accompanied by gain of inhibitory activity against porcine a-amylase. Made available in DSpace on 2011-04-09T17:31:39Z (GMT). No. of bitstreams: 1 v39n03a01.pdf: 128270 bytes, checksum: 34d0391b8e9601cc08c0776bb39c2877 (MD5) Previous issue date: 2007-08-27 |
| Databáze: | OpenAIRE |
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