Peroxidasin forms sulfilimine chemical bonds using hypohalous acids in tissue genesis

Abstract

Collagen IV is the predominant protein network of basement membranes, a specialized extracellular matrix, which underlie epithelia and endothelia. These networks assemble through oligomerization and covalent cross-linking to endow mechanical strength and shape cell behavior through interactions with cell surface receptors. A novel sulfilimine (S=N) bond between a methionine sulfur and hydroxylysine nitrogen reinforces the collagen IV network. We demonstrate that peroxidasin, an enzyme found in basement membranes, catalyzes formation of the sulfilimine bond. Drosophila peroxidasin mutants exhibit disorganized collagen IV networks and torn visceral muscle basement membranes pointing to a critical role for the enzyme in tissue biogenesis. Peroxidasin generates hypohalous acids as reaction intermediates suggesting a paradoxically anabolic role for these usually destructive oxidants. This work highlights sulfilimine bond formation as the first known physiologic function for peroxidasin, a role for hypohalous oxidants in tissue biogenesis, and a possible role for peroxidasin in inflammatory diseases.

Structure–function analysis of peroxidasin provides insight into the mechanism of collagen IV crosslinking

“…The animal heme peroxidase PXDN has been shown to catalyze the formation of sulfilimine links in a reaction, where the enzyme produces hypohalous acids as intermediates for the oxidation of a highly conserved Met residue in the NC1 domain (11). Although peroxidase inhibitors were previously shown to inhibit collagen IV crosslinking in a murine embryonic carcinoma cell line (11), evidence for PXDN-mediated coupling of NC1 domains being a physiological pathway of ECM formation in mammals has been lacking so far.…”

“…Collagen IV was recently identified as a substrate of PXDN (11). In a reaction thought to be universal in the animal kingdom the enzyme crosslinks the NC1 domains of collagen IV protomers through the formation of sulfilimine linkages.…”

“…Recently Bhave et al identified PXDN as the long-sought player in collagen IV biosynthesis that catalyzes crosslinking of collagen IV trimers through their NC1 domains (11). Coupling of the NC1 domains occurs through sulfilimine bonds that were only recently recognized in living organisms (12).…”

Proprotein Convertase Processing Enhances Peroxidasin Activity to Reinforce Collagen IV

“…Sulfilimine (SAN) bonds between opposing methionine and lysine residues bridge the trimer-timer interface of the NC1 hexamer and thereby structurally reinforce the collagen IV network (3). The enzyme peroxidasin (Pxdn), a basement membrane-associated heme peroxidase, catalyzes the formation of sulfilimine crosslinks, a process critical for BM and tissue integrity (4). For example, peroxidasin loss of function in Drosophila and Caenorhabditis elegans compromises gut architecture and leads to early lethality (4,5).…”

“…The enzyme peroxidasin (Pxdn), a basement membrane-associated heme peroxidase, catalyzes the formation of sulfilimine crosslinks, a process critical for BM and tissue integrity (4). For example, peroxidasin loss of function in Drosophila and Caenorhabditis elegans compromises gut architecture and leads to early lethality (4,5). In addition to structural reinforcement, the sulfilimine cross-link also confers immune privilege to the collagen IV auto-antigen in human Goodpasture's disease, a devastating condition presenting as rapidly progressive glomerulonephritis with or without pulmonary hemorrhage.…”