A defined α-helix in the bifunctional O-glycosylated natriuretic peptide TcNPa from the venom of Tropidechis carinatus.
Natriuretic peptides (NP) play important roles in human cardiac physiology through their guanylyl cyclase receptors NPR-A and NPR-B. Described herein is a bifunctional O-glycosylated natriuretic peptide, TcNPa, from Tropidechis carinatus venom and it unusually targets both NPR-A and NPR-B. Characterization using specific glycosidases and ETD-MS identified the glycan as galactosyl-β(1-3)-N-acetylgalactosamine (Gal-GalNAc) and was α-linked to the C-terminal threonine residue. TcNPa contains the characteristic NP 17-membered disulfide ring with conserved phenylalanine and arginine residues. Both glycosylated and nonglycosylated forms were synthesized by Fmoc solid-phase peptide synthesis and NMR analysis identified an α-helix within the disulfide ring containing the putative pharmacophore for NPR-A. Surprisingly, both forms activated NPR-A and NPR-B and were relatively resistant towards proteolytic degradation in plasma. This work will underpin the future development of bifunctional NP peptide mimetics.
Institute for Molecular Bioscience, The University of Queensland, Queensland 4072 (Australia). t.reeks@imb.uq.edu.au.
Timothy
T
Reeks
Alun
A
Jones
Andreas
A
Brust
Sindhuja
S
Sridharan
Leo
L
Corcilius
Brendan L
BL
Wilkinson
Morten
M
Thaysen-Andersen
Richard J
RJ
Payne
R Manjunatha
RM
Kini
Norelle L
NL
Daly
Paul F
PF
Alewood
D000595:Amino Acid Sequence; D000818:Animals; D017815:Elapidae / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D045265:Natriuretic Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D017461:Receptors, Atrial Natriuretic Factor / Q000737:chemistry / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D014688:Venoms / Q000378:metabolism*; D000099242:Atrial Natriuretic Factor Receptor B
D045265:Natriuretic Peptides; D017461:Receptors, Atrial Natriuretic Factor; D014688:Venoms; D000099242:Atrial Natriuretic Factor Receptor B; C091715:atrial natriuretic factor receptor A
Tropidechis carinatus; glycopeptide synthesis; helical structures; natriuretic peptide TcNPa; snake toxin