1. The three-dimensional structure of an H-superfamily conotoxin reveals a granulin fold arising from a common ICK cysteine framework
- Author
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Anastasia Albert, Lars Ellgaard, Mads M. Foged, Terje Vasskog, Samuel D. Robinson, Cecilie L. Søltoft, Raymond S. Norton, Baldomero M. Olivera, Kaare Teilum, Andreas B. Bertelsen, Anthony W. Purcell, Lau Dalby Nielsen, Steen V. Petersen, and Helena Safavi-Hemami
- Subjects
0301 basic medicine ,Protein Folding ,Magnetic Resonance Spectroscopy ,Cysteine/chemistry ,granulin ,Granulin ,PROTEIN ,Peptide ,Biochemistry ,Protein structure ,STACK ,Conotoxin ,Disulfides ,Protein disulfide-isomerase ,toxin ,CYSTINE KNOT ,Granulins ,chemistry.chemical_classification ,Granulins/chemistry ,biology ,Protein Stability ,CD spectroscopy ,inhibitor cystine knot ,Recombinant Proteins ,FAMILY ,protein-disulfide isomerase ,THERAPEUTICS ,Protein Structure and Folding ,conotoxin ,VENOM PEPTIDES ,Stereochemistry ,PHASE ,Mollusk Venoms ,Conus Snail/metabolism ,03 medical and health sciences ,NMR spectroscopy ,protein conformation ,antistasin ,Animals ,Conus victoriae ,Amino Acid Sequence ,Cysteine ,protein structure ,Recombinant Proteins/biosynthesis ,protein evolution ,Molecular Biology ,protein expression ,030102 biochemistry & molecular biology ,Conus Snail ,Cell Biology ,biology.organism_classification ,2 BETA-HAIRPINS ,030104 developmental biology ,chemistry ,Conotoxins/chemistry ,Mollusk Venoms/metabolism ,disulfide bond ,Protein Conformation, beta-Strand ,Inhibitor cystine knot ,CHEMICAL-SHIFTS ,Conotoxins ,Disulfides/chemistry ,hairpin ,COEFFICIENTS ,disulfide - Abstract
Venomous marine cone snails produce peptide toxins (conotoxins) that bind ion channels and receptors with high specificity and therefore are important pharmacological tools. Conotoxins contain conserved cysteine residues that form disulfide bonds that stabilize their structures. To gain structural insight into the large, yet poorly characterized conotoxin H-superfamily, we used NMR and CD spectroscopy along with MS-based analyses to investigate H-Vc7.2 from Conus victoriae, a peptide with a VI/VII cysteine framework. This framework has CysI-CysIV/CysII-CysV/CysIII-CysVI connectivities, which have invariably been associated with the inhibitor cystine knot (ICK) fold. However, the solution structure of recombinantly expressed and purified H-Vc7.2 revealed that although it displays the expected cysteine connectivities, H-Vc7.2 adopts a different fold consisting of two stacked -hairpins with opposing -strands connected by two parallel disulfide bonds, a structure homologous to the N-terminal region of the human granulin protein. Using structural comparisons, we subsequently identified several toxins and nontoxin proteins with this “mini-granulin” fold. These findings raise fundamental questions concerning sequence-structure relationships within peptides and proteins and the key determinants that specify a given fold.
- Published
- 2019
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