TY - JOUR

T1 - The three-dimensional structure of an H-superfamily conotoxin reveals a granulin fold arising from a common ICK cysteine framework

AU - Nielsen, Lau D

AU - Foged, Mads M.

AU - Albert, Anastasia

AU - Bertelsen, Andreas B.

AU - Søltoft, Cecilie L

AU - Robinson, Samuel D.

AU - Petersen, Steen Vang

AU - Purcell, Anthony W.

AU - Olivera, Baldomero M.

AU - Norton, Raymond S.

AU - Vasskog, Terje

AU - Safavi-Hemami, Helena

AU - Teilum, Kaare

AU - Ellgaard, Lars

N1 - Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

PY - 2019

Y1 - 2019

N2 - 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 β-hairpins with opposing β-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.

AB - 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 β-hairpins with opposing β-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.

U2 - 10.1074/jbc.RA119.007491

DO - 10.1074/jbc.RA119.007491

M3 - Journal article

C2 - 30975904

VL - 294

SP - 8745

EP - 8759

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 22

ER -