Inhibitory specificity and insecticidal selectivity of alpha-amylase inhibitor from Phaseolus vulgaris.
The primary structure and proteolytic processing of the alpha-amylase isoinhibitor alpha AI-1 from common bean (Phaseolus vulgaris cv. Magna) was determined by protein chemistry techniques. The inhibitory specificity of alphaAI-1 was screened with a panel of the digestive alpha-amylases from 30 species of insects, mites, gastropod, annelid worm, nematode and fungal phytopathogens with a focus on agricultural pests and important model species. This in vitro analysis showed a selective inhibition of alpha-amylases from three orders of insect (Coleoptera, Hymenoptera and Diptera) and an inhibition of alpha-amylases of the annelid worm. The inhibitory potential of alphaAI-1 against several alpha-amylases was found to be modulated by pH. To understand how alphaAI-1 discriminates among closely related alpha-amylases, the sequences of the alpha-amylases sensitive, respectively, insensitive to alphaAI-1 were compared, and the critical determinants were localized on the spatial alpha-amylase model. Based on the in vitro analysis of the inhibitory specificity of alphaAI-1, the in vivo activity of the ingested alphaAI-1 was demonstrated by suppression of the development of the insect larvae that expressed the sensitive digestive alpha-amylases. The first comprehensive mapping of alphaAI-1 specificity significantly broadens the spectrum of targets that can be regulated by alpha-amylase inhibitors of plant origin, and points to potential application of these protein insecticides in plant biotechnologies.
Kluh
Ivan
I
Department of Protein Biochemistry, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of The Czech Republic, Flemingovo nam. 2, 166 10, Praha 6, Czech Republic.
Horn
Martin
M
Hýblová
Jana
J
Hubert
Jan
J
Dolecková-Maresová
Lucie
L
Voburka
Zdenek
Z
Kudlíková
Iva
I
Kocourek
Frantisek
F
Mares
Michael
M
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000201:enzymology; D005658:Fungi / Q000201:enzymology; D006372:Helix, Snails / Q000201:enzymology; D007313:Insecta / Q000201:enzymology; D007306:Insecticides / Q000737:chemistry* / Q000494:pharmacology*; D008925:Mites / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009835:Oligochaeta / Q000201:enzymology; D027805:Phaseolus / Q000737:chemistry*; D037121:Plant Lectins / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding; D013379:Substrate Specificity; D000516:alpha-Amylases / Q000037:antagonists & inhibitors*
D007306:Insecticides; D037121:Plant Lectins; C061510:alpha-amylase inhibitor, Phaseolus vulgaris; D000516:alpha-Amylases