| Structural highlights
Function
PA2H1_BOTJR Snake venom phospholipase A2 homolog that lacks enzymatic activity. Shows local myotoxic activity (PubMed:11018293, PubMed:12079495, PubMed:31906173). Induces inflammation, since it induces edema and leukocytes infiltration (PubMed:11018293, PubMed:31906173). In addition, it induces NLRP3 NLRP3, ASC (PYCARD), caspase-1 (CASP1), and IL-1beta (IL1B) gene expression in the gastrocnemius muscle, showing that it is able to activate NLRP3 inflammasome (PubMed:31906173). It also damages artificial and myoblast membranes by a calcium-independent mechanism, has bactericidal activity, and induces neuromuscular blockade (PubMed:27531710). A model of myotoxic mechanism has been proposed: an apo Lys49-PLA2 is activated by the entrance of a hydrophobic molecule (e.g. fatty acid) at the hydrophobic channel of the protein leading to a reorientation of a monomer (PubMed:27531710) (By similarity). This reorientation causes a transition between 'inactive' to 'active' states, causing alignment of C-terminal and membrane-docking sites (MDoS) side-by-side and putting the membrane-disruption sites (MDiS) in the same plane, exposed to solvent and in a symmetric position for both monomers (PubMed:27531710) (By similarity). The MDoS region stabilizes the toxin on membrane by the interaction of charged residues with phospholipid head groups (PubMed:27531710) (By similarity). Subsequently, the MDiS region destabilizes the membrane with penetration of hydrophobic residues (PubMed:27531710) (By similarity). This insertion causes a disorganization of the membrane, allowing an uncontrolled influx of ions (i.e. calcium and sodium), and eventually triggering irreversible intracellular alterations and cell death (PubMed:27531710) (By similarity).[UniProtKB:I6L8L6][1] [2] [3] [4] [5] [6] [7] [8] [9]
Publication Abstract from PubMed
BACKGROUND: One of the main challenges in snakebite envenomation treatment is the development of stable, versatile and efficient anti-venom therapies. Local myotoxicity in accidents involving snakes from the Bothrops genus is still a consequence of serum therapy inefficient neutralization that may lead to permanent sequelae in their victims. One of the classes of toxins that participate in muscle necrosis is the PLA2-like proteins. The aim of this work was to investigate the role of zinc ions in the inhibition of PLA2-like proteins and to advance the current knowledge of their action mechanism. METHODS: Myographic and electrophysiological techniques were used to evaluate the inhibitory effect of zinc ions, isothermal titration calorimetry assays were used to measure the affinity between zinc ions and the toxin and X-ray crystallography was used to reveal details of this interaction. RESULTS: We demonstrated that zinc ions can effectively inhibit the toxin by the interaction with two different sites, which are related to two different mechanism of inhibition: preventing membrane disruption and impairing the toxin state transition. Furthermore, structural study presented here included an additional step in the current myotoxic mechanism improving the comprehension of the allosteric transition that PLA2-like proteins undergo to exert their function. CONCLUSIONS: Our findings show that zinc ions are inhibitors of PLA2-like proteins and suggest two different mechanisms of inhibition for these ions. GENERAL SIGNIFICANCE: Zinc is a new candidate that can assist in anti-venom treatments and can promote the design of new and even more accurate structure-based inhibitors for PLA2-like proteins.
Functional and structural studies of a Phospholipase A2-like protein complexed to zinc ions: Insights on its myotoxicity and inhibition mechanism.,Borges RJ, Cardoso FF, Fernandes CA, Dreyer TR, de Moraes DS, Floriano RS, Rodrigues-Simioni L, Fontes MR Biochim Biophys Acta. 2017 Jan;1861(1 Pt A):3199-3209. doi:, 10.1016/j.bbagen.2016.08.003. Epub 2016 Aug 13. PMID:27531710[10]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Andriao-Escarso SH, Soares AM, Rodrigues VM, Angulo Y, Diaz C, Lomonte B, Gutierrez JM, Giglio JR. Myotoxic phospholipases A(2) in bothrops snake venoms: effect of chemical modifications on the enzymatic and pharmacological properties of bothropstoxins from Bothrops jararacussu. Biochimie. 2000 Aug;82(8):755-63. PMID:11018293
- ↑ Ward RJ, Chioato L, de Oliveira AH, Ruller R, Sa JM. Active-site mutagenesis of a Lys49-phospholipase A2: biological and membrane-disrupting activities in the absence of catalysis. Biochem J. 2002 Feb 15;362(Pt 1):89-96. PMID:11829743
- ↑ Chioato L, De Oliveira AH, Ruller R, Sa JM, Ward RJ. Distinct sites for myotoxic and membrane-damaging activities in the C-terminal region of a Lys49-phospholipase A2. Biochem J. 2002 Sep 15;366(Pt 3):971-6. PMID:12079495 doi:http://dx.doi.org/10.1042/BJ20020092
- ↑ Murakami MT, Vicoti MM, Abrego JR, Lourenzoni MR, Cintra AC, Arruda EZ, Tomaz MA, Melo PA, Arni RK. Interfacial surface charge and free accessibility to the PLA2-active site-like region are essential requirements for the activity of Lys49 PLA2 homologues. Toxicon. 2007 Mar 1;49(3):378-87. Epub 2006 Nov 3. PMID:17157889 doi:10.1016/j.toxicon.2006.10.011
- ↑ Chioato L, Aragao EA, Lopes Ferreira T, Medeiros AI, Faccioli LH, Ward RJ. Mapping of the structural determinants of artificial and biological membrane damaging activities of a Lys49 phospholipase A2 by scanning alanine mutagenesis. Biochim Biophys Acta. 2007 May;1768(5):1247-57. Epub 2007 Feb 9. PMID:17346668 doi:http://dx.doi.org/10.1016/j.bbamem.2007.01.023
- ↑ Aragao EA, Chioato L, Ward RJ. Permeabilization of E. coli K12 inner and outer membranes by bothropstoxin-I, A LYS49 phospholipase A2 from Bothrops jararacussu. Toxicon. 2008 Mar 15;51(4):538-46. Epub 2007 Nov 17. PMID:18160090 doi:http://dx.doi.org/10.1016/j.toxicon.2007.11.004
- ↑ Borges RJ, Cardoso FF, Fernandes CA, Dreyer TR, de Moraes DS, Floriano RS, Rodrigues-Simioni L, Fontes MR. Functional and structural studies of a Phospholipase A2-like protein complexed to zinc ions: Insights on its myotoxicity and inhibition mechanism. Biochim Biophys Acta. 2017 Jan;1861(1 Pt A):3199-3209. doi:, 10.1016/j.bbagen.2016.08.003. Epub 2016 Aug 13. PMID:27531710 doi:http://dx.doi.org/10.1016/j.bbagen.2016.08.003
- ↑ Homsi-Brandeburgo MI, Queiroz LS, Santo-Neto H, Rodrigues-Simioni L, Giglio JR. Fractionation of Bothrops jararacussu snake venom: partial chemical characterization and biological activity of bothropstoxin. Toxicon. 1988;26(7):615-27. PMID:3176051
- ↑ Boeno CN, Paloschi MV, Lopes JA, Pires WL, Setubal SDS, Evangelista JR, Soares AM, Zuliani JP. Inflammasome Activation Induced by a Snake Venom Lys49-Phospholipase A2 Homologue. Toxins (Basel). 2019 Dec 31;12(1). pii: toxins12010022. doi:, 10.3390/toxins12010022. PMID:31906173 doi:http://dx.doi.org/10.3390/toxins12010022
- ↑ Borges RJ, Cardoso FF, Fernandes CA, Dreyer TR, de Moraes DS, Floriano RS, Rodrigues-Simioni L, Fontes MR. Functional and structural studies of a Phospholipase A2-like protein complexed to zinc ions: Insights on its myotoxicity and inhibition mechanism. Biochim Biophys Acta. 2017 Jan;1861(1 Pt A):3199-3209. doi:, 10.1016/j.bbagen.2016.08.003. Epub 2016 Aug 13. PMID:27531710 doi:http://dx.doi.org/10.1016/j.bbagen.2016.08.003
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