SDS‑induced hexameric oligomerization of myotoxin‑II from Bothrops asper assessed by sedimentation velocity and nuclear magnetic resonance
Fecha
2023
Tipo
artículo original
Autores
Henrickson, Amy
Montina, Tony
Hazendonk, Paul
Lomonte, Bruno
Neves Ferreira, Ana Gisele da Costa
Demeler, Borries
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Resumen
We report the solution behavior, oligomerization state, and structural details of myotoxin-II purified from the venom of
Bothrops asper in the presence and absence of sodium dodecyl sulfate (SDS) and multiple lipids, as examined by analytical
ultracentrifugation and nuclear magnetic resonance. Molecular functional and structural details of the myotoxic mechanism
of group II Lys-49 phospholipase A2
homologues have been only partially elucidated so far, and conflicting observations
have been reported in the literature regarding the monomeric vs. oligomeric state of these toxins in solution. We observed
the formation of a stable and discrete, hexameric form of myotoxin-II, but only in the presence of small amounts of SDS.
In SDS-free medium, myotoxin-II was insensitive to mass action and remained monomeric at all concentrations examined
(up to 3 mg/ml, 218.2 μM). At SDS concentrations above the critical micelle concentration, only dimers and trimers were
observed, and at intermediate SDS concentrations, aggregates larger than hexamers were observed. We found that the amount
of SDS required to form a stable hexamer varies with protein concentration, suggesting the need for a precise stoichiometry
of free SDS molecules. The discovery of a stable hexameric species in the presence of a phospholipid mimetic suggests a
possible physiological role for this oligomeric form, and may shed light on the poorly understood membrane-disrupting
mechanism of this myotoxic protein class.
Descripción
Palabras clave
Myotoxin II, SDS, analytical ultracentrifugation, Lys-49, Bothrops asper