The Spn4 gene from Drosophila melanogaster is a multipurpose defence tool directed against proteases from three different peptidase families.
By alternative use of four RSL (reactive site loop) coding exon cassettes, the serpin (serine protease inhibitor) gene Spn4 from Drosophila melanogaster was proposed to enable the synthesis of multiple protease inhibitor isoforms, one of which has been shown to be a potent inhibitor of human furin. Here, we have investigated the inhibitory spectrum of all Spn4 RSL variants. The analyses indicate that the Spn4 gene encodes inhibitors that may inhibit serine proteases of the subtilase family (S8), the chymotrypsin family (S1), and the papain-like cysteine protease family (C1), most of them at high rates. Thus a cohort of different protease inhibitors is generated simply by grafting enzyme-adapted RSL sequences on to a single serpin scaffold, even though the target proteases contain different types and/or a varying order of catalytic residues and are descendents of different phylogenetic lineages. Since all of the Spn4 RSL isoforms are produced as intracellular residents and additionally as variants destined for export or associated with the secretory pathway, the Spn4 gene represents a versatile defence tool kit that may provide multiple antiproteolytic functions.
Brüning
Mareke
M
Department of Biotechnology, Faculty of Technology, University of Bielefeld, D-33501 Bielefeld, Germany.
Lummer
Martina
M
Bentele
Caterina
C
Smolenaars
Marcel M W
MM
Rodenburg
Kees W
KW
Ragg
Hermann
H
D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D029721:Drosophila Proteins / Q000737:chemistry / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000201:enzymology; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors / Q000097:blood; D010447:Peptide Hydrolases / Q000378:metabolism*; D011480:Protease Inhibitors / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015843:Serpins / Q000737:chemistry / Q000378:metabolism*
D029721:Drosophila Proteins; D011480:Protease Inhibitors; D015843:Serpins; C488721:Spn42Da protein, Drosophila; D010447:Peptide Hydrolases; D010196:Pancreatic Elastase