The astacin metalloprotease moulting enzyme NAS-36 is required for normal cuticle ecdysis in free-living and parasitic nematodes

Abstract

S U M M A R YNematodes represent one of the most abundant and species-rich groups of animals on the planet, with parasitic species causing chronic, debilitating infections in both livestock and humans worldwide. The prevalence and success of the nematodes is a direct consequence of the exceptionally protective properties of their cuticle. The synthesis of this cuticle is a complex multi-step process, which is repeated 4 times from hatchling to adult and has been investigated in detail in the freeliving nematode, Caenorhabditis elegans. This process is known as moulting and involves numerous enzymes in the synthesis and degradation of the collagenous matrix. The nas-36 and nas-37 genes in C. elegans encode functionally conserved enzymes of the astacin metalloprotease family which, when mutated, result in a phenotype associated with the late-stage moulting defects, namely the inability to remove the preceding cuticle. Extensive genome searches in the gastrointestinal nematode of sheep, Haemonchus contortus, and in the filarial nematode of humans, Brugia malayi, identified NAS-36 but not NAS-37 homologues †. Significantly, the nas-36 gene from B. malayi could successfully complement the moult defects associated with C. elegans nas-36, nas-37 and nas-36/nas-37 double mutants, suggesting a conserved function for NAS-36 between these diverse nematode species. This conservation between species was further indicated when the recombinant enzymes demonstrated a similar range of inhibitable metalloprotease activities.

Enzymology of the nematode cuticle: A potential drug target?

“…The B. malayi gene can complement C. elegans strains mutant in either nas-36 or nas-37 , and a combined mutant of nas-36 / nas-37 , indicating that NAS-36 is the dominant molecule involved in cuticle ecdysis in parasitic nematodes. This result also confirmed that NAS-36 metalloprotease plays a functionally conserved role in phylogenetically divergent nematode species (Stepek et al, 2011). …”

Secreted Proteomes of Different Developmental Stages of the Gastrointestinal Nematode Nippostrongylus brasiliensis

“…S. stercoralis strongylastacin is only expressed by L3, and it is thought to be involved in the invasion process (75). Other astacins such as NAS-36 and NAS-37 from the free-living nematode C. elegans, play important roles in cuticle ecdysis during moulting (71,76), whereas NAS-36 homologs from the parasitic nematodes H. contortus and B. malayi play important functions in parasite development (77,78). A phylogenetic analysis of astacins from N. brasiliensis and other nematodes revealed a monophyletic clade formed exclusively by selected sequences from adult N. brasiliensis ESP (i.e.…”

C. elegans NIMA-related kinases NEKL-2 and NEKL-3 are required for the completion of molting

“…In C. elegans , inactivation of many individual genes by mutation or by RNA interference (RNAi) results in a frequent failure to shed the old cuticle completely (Frand et al, 2005; Kang et al, 2013). Gene products required for proper molting include nuclear hormone receptors (Gissendanner and Sluder, 2000; Hayes et al, 2006; Kostrouchova et al, 1998, 2001; Monsalve and Frand, 2012), matrix metalloproteases (Altincicek et al, 2010; Davis et al, 2004; Hashmi et al, 2004; Kim et al, 2011; Stepek et al, 2011; Suzuki et al, 2004), selenoproteins (Stenvall et al, 2011), enzymes controlling sterol and fatty acid synthesis (Entchev and Kurzchalia, 2005; Jia et al, 2002; Kuervers et al, 2003; Li and Paik, 2011), hedgehog-related proteins (Hao et al, 2006; Zugasti et al, 2005), and LRP-1, an ortholog of megalin, a large member of the LDL receptor family (Yochem et al, 1999). A number of molting genes are associated with secretion, endocytosis, and vesicle trafficking (Frand et al, 2005; Kang et al, 2013; Liegeois et al, 2007), and several of these, including the Disabled adaptor ortholog dab-1 , the Saccharomyces cerevisiae Vps27p ortholog hgrs-1, and the S. cerevisiae Sec23p ortholog sec-23 , affect trafficking and endocytosis of LRP-1 from the apical membrane of hyp7 (Holmes et al, 2007; Kamikura and Cooper, 2006; Kang et al, 2013; Roberts et al, 2003; Roudier et al, 2005).…”