Differential Evolution and Neofunctionalization of Snake Venom Metalloprotease Domains

Abstract

Snake venom metalloproteases (SVMP) are composed of five domains: signal peptide, propeptide, metalloprotease, disintegrin, and cysteine-rich. Secreted toxins are typically combinatorial variations of the latter three domains. The SVMP-encoding genes of Psammophis mossambicus venom are unique in containing only the signal and propeptide domains. We show that the Psammophis SVMP propeptide evolves rapidly and is subject to a high degree of positive selection. Unlike Psammophis, some species of Echis express both the typical multidomain and the unusual monodomain (propeptide only) SVMP, with the result that a lower level of variation is exerted upon the latter. We showed that most mutations in the multidomain Echis SVMP occurred in the protease domain responsible for proteolytic and hemorrhagic activities. The cysteinerich and disintegrin-like domains, which are putatively responsible for making the P-III SVMPs more potent than the P-I and P-II forms, accumulate the remaining variation. Thus, the binding sites on the molecule's surface are evolving rapidly whereas the core remains relatively conserved. Bioassays conducted on two post-translationally cleaved novel proline-rich peptides from the P. mossambicus propeptide domain showed them to have been neofunctionalized for specific inhibition of mammalian a7 neuronal nicotinic acetylcholine receptors. We show that the proline rich postsynaptic specific neurotoxic peptides from Azemiops feae are the result of convergent evolution within the precursor region of the C-type na- Snake venom metalloproteases (SVMP)1 evolved from ADAM (A disintegrin and metalloprotease) proteins that were recruited into the venom of snakes near the base of the advanced snake (Caenophidia) radiation. They have been identified in the venoms of all lineages of advanced snakes (1-5). The ancestral SVMP (P-III) contains (in downstream order) five domains: signal ϩ propeptide ϩ metalloprotease ϩ disintegrin ϩ cysteine rich. Following the divergence of vipers from the remaining caenophidians, extensive gene duplication, domain loss, and positive selection resulted in generation of the P-I and P-II classes of SVMP within the viperid lineage (6 -8). These two derived classes found in viper venoms lack either the cysteine-rich domain (P-II) or the cysteinerich and disintegrin domains (P-I) (8, 9). The signal peptide and the propeptide domain are typically cleaved off before expression although the latter has been detected in venoms on occasion (9). SVMP are often the dominant venom component in the venom of viperid snakes, but are typically much less significant in the venom of other snake families (10 -15). The majority of SVMP principally exhibit hemorrhagic activity, although other functions, such as the activation of prothrombin and Factor X, fibrin(ogen)olysis, apoptosis and the inhibition of platelet aggregation, have also been reported (16). Although SVMP-induced hemorrhage is primarily dependent on the proteolytic activity of the metalloprotease domain, the potency of this activity is incr...

What killed Karl Patterson Schmidt? Combined venom gland transcriptomic, venomic and antivenomic analysis of the South African green tree snake (the boomslang), Dispholidus typus

“…All of the SVMP contigs we identified were members of the P-III class, which is unsurprising considering that P-II and P-I SVMPs have only previously been detected from viperid snakes [43], [44]. It is worth noting that we did not find any evidence of any atypical truncated SVMPs such as those previously described from the non-front-fanged snake Psammophis mossambicus (family Lamprophiidae) [45]. Phylogenetic analysis of boomslang SVMPs with representative orthologs from other taxa revealed that all but one of the boomslang SVMPs group together in a clade sister to that containing SVMPs from the xenodontid snake Philodryas olfersii , the atractaspid Atractaspis microlepidotus and various elapid snakes (Fig.…”

Multifunctional Toxins in Snake Venoms and Therapeutic Implications: From Pain to Hemorrhage and Necrosis

“…Acute pain through ASIC1 activation (Bohlen et al, 2011) Inflammatory pain, thermal hypersalgesia and mechanical allodynia (Zhang et al, 2017) Excitation of sensory neurons (Bohlen et al, 2011;Zhang et al, 2017) Neurogenic inflammation (Camara et al, 2003;Camargo et al, 2008) Non-neurogenic inflammation Endematogenic and pro-inflammatory (Camara et al, 2003;Casais-E-Silva et al, 2016;Costa et al, 2017) Inhibits platelet aggregation (Teixeira et al, 2011) Phospholipase activity (Gutierrez and Ownby, 2003) Myotoxic (Harris and Maltin, 1982) Pre-synaptic toxin, block of neuromuscular transmission leading to muscle paralysis (Sribar et al, 2014;Gutierrez et al, 2017) SVMP Inflammatory hyperalgesia (Fernandes et al, 2007;Bernardes et al, 2015;De Toni et al, 2015;Ferraz et al, 2015) Endematogenic activity independent of pro-inflammatory mediators (Laing et al, 2003) Cleavage of basement membrane of capillary vessels and endothelial cells adhesion proteins (Gutierrez et al, 2005;Escalante et al, 2011) Procoagulant through activation of prothrombin and Factor X (Takeda et al, 2012;Ainsworth et al, 2018) Inhibition of platelet aggregation (Kamiguti, 2005) Dermonecrotic activity dependent on TNF signaling (Laing et al, 2003) Potential paralysis through inhibition of α-7 neuronal AChR by the cysteine-rich and disintregin-like domains complex (Brust et al, 2013) SVSP Mild mechanical hyperalgesia (Menaldo et al, 2013) Leucocyte migration (Menaldo et al, 2013) Mild edema (Zychar et al, 2010) Procoagulant through activation of prothrombin and factors VII and X (Kini, 2005) Anti-coagulant through activation of Prot...…”

CHAPTER 4. Venoms-Based Drug Discovery: Bioassays, Electrophysiology, High-Throughput Screens and Target Identification

“…They have also been used in recent years for the discovery, isolation and characterisation of bioactive peptides from snakes, spiders and cone snails. [134][135][136] Due to the ubiquitous nature of the Ca 2+ signal, the large Ca 2+ gradient across cell membranes and superior spectrophotometric properties of Ca 2+ dyes, 137 high-throughput Ca 2+ assays are particularly attractive for isolating, identifying and characterising venom components with activity at a range of voltage-and ligand-gated ion channels (e.g. TRP channels and nAChRs) and GPCRs.…”