Premium
Structural stabilization of botulinum neurotoxins by tyrosine phosphorylation
Author(s) -
Encinar José A,
Fernández Asia,
Ferragut José A,
González-Ros José M,
DasGupta Bibhuti R,
Montal Mauricio,
Ferrer-Montiel Antonio
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00571-7
Subject(s) - thermostability , phosphorylation , chemistry , tyrosine , fourier transform infrared spectroscopy , protein secondary structure , random coil , tyrosine phosphorylation , biophysics , denaturation (fissile materials) , differential scanning calorimetry , biochemistry , biology , nuclear chemistry , chemical engineering , enzyme , physics , engineering , thermodynamics
Tyrosine phosphorylation of botulinum neurotoxins augments their proteolytic activity and thermal stability, suggesting a substantial modification of the global protein conformation. We used Fourier‐transform infrared (FTIR) spectroscopy to study changes of secondary structure and thermostability of tyrosine phosphorylated botulinum neurotoxins A (BoNT A) and E (BoNT E). Changes in the conformationally‐sensitive amide I band upon phosphorylation indicated an increase of the α‐helical content with a concomitant decrease of less ordered structures such as turns and random coils, and without changes in β‐sheet content. These changes in secondary structure were accompanied by an increase in the residual amide II absorbance band remaining upon H‐D exchange, consistent with a tighter packing of the phosphorylated proteins. FTIR and differential scanning calorimetry (DSC) analyses of the denaturation process show that phosphorylated neurotoxins denature at temperatures higher than those required by non‐phosphorylated species. These findings indicate that tyrosine phosphorylation induced a transition to higher order and that the more compact structure presumably imparts to the phosphorylated neurotoxins the higher catalytic activity and thermostability.