1p8b
From Proteopedia
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SOLUTION STRUCTURE OF PA1B, A 37-AMINO ACID INSECTICIDAL PROTEIN EXTRACTED FROM PEA SEEDS (PISUM SATIVUM)
Overview
PA1b (pea albumin 1, subunit b) is a 37-amino acid cysteine-rich plant, defense protein isolated from pea seeds (Pisum sativum). It induces, short-term mortality in several pests, among which the cereal weevils, Sitophilus sp. (Sitophilus oryzae, Sitophilus granarius, and Sitophilus, zeamais) that are a major nuisance for stored cereals, all over the world., As such, PA1b is the first genuine protein phytotoxin specifically toxic, to insects, which makes it a promising tool for seed weevil damage, control. We have determined the 3-D solution structure of PA1b, using 2-D, homonuclear proton NMR methods and molecular modeling. The primary, sequence of the protein does not share similarities with other known, toxins. It includes six cysteines forming three disulfide bridges., However, because of PA1b resistance to protease cleavage, conventional, methods failed to establish the connectivity pattern. Our first attempts, to assign the disulfide network from NOE data alone remained unsuccessful, due to the tight packing of the cysteine residues within the core of the, molecule. Yet, the use of ambiguous disulfide restraints within ARIA, allowed us to establish that PA1b belongs to the inhibitor cystine-knot, family. It exhibits the structural features that are characteristic of the, knottin fold, namely, a triple-stranded antiparallel beta-sheet with a, long flexible loop connecting the first to the second strand and a series, of turns. A comparison of the structural properties of PA1b with that of, structurally related proteins adopting a knottin fold and exhibiting a, diverse range of biological activities shows that the electrostatic and, lipophilic potentials at the surface of PA1b are very close to those found, for the spider toxin ACTX-Hi:OB4219, thereby suggesting activity on ion, channels.
About this Structure
1P8B is a Single protein structure of sequence from Pisum sativum. Full crystallographic information is available from OCA.
Reference
PA1b, an insecticidal protein extracted from pea seeds (Pisum sativum): 1H-2-D NMR study and molecular modeling., Jouvensal L, Quillien L, Ferrasson E, Rahbe Y, Gueguen J, Vovelle F, Biochemistry. 2003 Oct 21;42(41):11915-23. PMID:14556622
Page seeded by OCA on Tue Nov 20 23:35:21 2007
