There is little information on the egg proteins of gastropod mollusks. Here we focus on PV2, a novel neurotoxin from snail eggs, studying its size, shape, structure, and stability, using small angle X-ray scattering (SAXS), absorption and fluorescence spectroscopy, circular dichroism, electron microscopy and partial proteolysis. Results indicate that PV2 is a compact and well folded oligomer of 130x44 A. It is an octamer of four 98 kDa heterodimers composed of 67 and 31 kDa subunits. Subunits are held together by disulfide bonds. Dimers are assembled into native PV2 by non-covalent forces. The larger subunit is more susceptible to proteolysis, indicating it is less compactly folded and/or more exposed. Quenching of tryptophan fluorescence showed a single class of tryptophyl side chains occluded in hydrophobic regions. Native structure shows loss of secondary structure (alpha+beta) at 6 M urea or 60-70 degrees C; the effects on the quaternary structure suggest an unfolding without disassembling of the protein. The 3D model of PV2 presented here is the first for an egg proteinaceous neurotoxin in animals. Study holds ProTherm entries: 25743, 25744 Extra Details: Neurotoxin; Perivitellin; 3D structure; Protein stability; Quaternary protein structure; Snail; Mollusc
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:56 p.m.
|Number of data points||2|
|Proteins||Perivitellin-2 67 kDa subunit|
|Assays/Quantities/Protocols||Experimental Assay: Tm pH:7.4, ionic:: , prot_conc:0.15 microM ; Experimental Assay: Tm pH:7.0, ionic:NaCl: 50 mM, prot_conc:1.2 microM|
|Libraries||Mutations for sequence MSQLRWWVVSQLLLLIVVCILDHSEGARVCPKIVPGLDKLRVGVDITKLDLLPLFDLGDNGFRSAVADYTCDRGQTTVVDGESFDVPDQVDSVVIESSGQQTSSVTTIKSESQISQALSISAGISVDTAKAGFSSSASYAEMQEAITKYGRTVSQMSAVYTTCSANLSPNLLLGQNPLQTLSRLPSDFTADTEGYYDFIKTYGTHYFNKGKLGGMFLFTSETDMSYFQNKNSQQVEANIKATFASILSTETGGSSDQSKEVIEFKESSLITAKFFGGRTNLAADGLTKWQPTIAKLPYFMSGTLSTISSLIADTTKRASMELAVKNYLLKAKVANLDRLTYIRLNSWTVGHNELRDLSAQLQNLKKKTIFSDEDEKLLQSIEDQVSVPAWFSDRTTFCFRSTAVGSADQCNGQSTSTLCAEPNRYTQQYMDKTYLGDTGCRLVWKLSTTESSDWFKSVKVNFRWYPTWSPCACGPVGTPFTISAPANSWTQDYLDVTNPKFGECMLQWMIEVPPTATLWAKNLEFCIDFTCGKKKQCVDANHWTEPYLDISAHEACGMSWALIAK|