Biochemical characterization of prostasin, a channel activating protease.
Human prostasin was recently identified as a potential regulator of epithelial sodium channel (ENaC) function. Through the use of positional scanning combinatorial substrate libraries, prostasin was shown to have a preference for poly-basic substrates: in position P4 preference was for arginine or lysine; in P3 preference was for histidine, lysine or arginine; in P2 preference was for basic or large hydrophobic amino acids; and in P1 preference was for arginine and lysine. P1', P2', and P3' displayed broad selectivity with the exception of a lack of activity for isoleucine, and P4' had a preference for small, unbranched, amino acids such as alanine and serine. A prostasin-preferred poly-basic cleavage site was found in the extracellular domains of the ENaC alpha- and beta-subunits, and may present a mechanism for prostasin activation. The absence of activity seen with substrates containing isoleucine in position P1' explains the inability of prostasin to autoactivate and suggests that prostasin proteolytic activity is regulated by an upstream protease. Prostasin activity was highly influenced by mono- and divalent metal ions which were potent inhibitors and substrate specific modulators of enzymatic activity. In the presence of sub-inhibitory concentrations of zinc, the activity of prostasin increased several-fold and its substrate specificity was significantly altered in favor of a strong preference for histidine in positions P3 or P4 of the substrate.
Genomics Institute of the Novartis Research Foundation, 10675 John Jay Hopkins Drive, San Diego, CA 92121, USA.
Aaron
A
Shipway
Henry
H
Danahay
Jennifer A
JA
Williams
David C
DC
Tully
Bradley J
BJ
Backes
Jennifer L
JL
Harris
D000818:Animals; D000838:Anions; D001120:Arginine / Q000737:chemistry; D001665:Binding Sites; D015153:Blotting, Western; D002412:Cations; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D053503:Epithelial Sodium Channels; D015723:Gene Library; D006639:Histidine / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007313:Insecta; D007477:Ions; D007700:Kinetics; D008239:Lysine / Q000737:chemistry; D008670:Metals / Q000737:chemistry; D008957:Models, Genetic; D010447:Peptide Hydrolases / Q000378:metabolism*; D019151:Peptide Library; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000502:physiology*; D015222:Sodium Channels / Q000737:chemistry; D013379:Substrate Specificity; D015032:Zinc / Q000737:chemistry; D000099271:Prostasin
D000838:Anions; D001120:Arginine; D002412:Cations; D018076:DNA, Complementary; D053503:Epithelial Sodium Channels; D006639:Histidine; D007477:Ions; D008239:Lysine; D008670:Metals; D010447:Peptide Hydrolases; D019151:Peptide Library; D011994:Recombinant Proteins; D012697:Serine Endopeptidases; D015222:Sodium Channels; D015032:Zinc; D000099271:Prostasin