Influence of Ca2+ and pH on the folding of the prourotensin II precursor

• Published in: FEBS letters Vol. 585; no. 12; pp. 1910 - 1914
• Main Authors: Bilodeau, Josée, Désilets, Antoine, McDuff, François-Olivier, St-Pierre, Caroline, Barbar, Élie, Leduc, Richard, Lavigne, Pierre
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 23.06.2011
• Subjects: Animals; Calcium - pharmacology; circular dichroism; Convertase; GnHCl; guanidine hydrochloride; Humans; Hydrogen-Ion Concentration; IPTG; isopropyl-β-d-1-thiogalactopyranoside; Mice; PC1/3; PC2; Precursor protein; proprotein convertase 1; proprotein convertase 2; Protein Conformation - drug effects; Protein folding; Protein Folding - drug effects; Protein Precursors - chemistry; Protein Stability - drug effects; ProUII; prourotensin II; Secretory Vesicles - metabolism; TCEP; tris(2-carboxyethyl) phosphine; Urotensin II; Urotensins - chemistry; GnHCl; CD; PC1/3; ProUII; Protein folding; IPTG; Precursor protein; Urotensin II; Convertase; TCEP; PC2
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/j.febslet.2011.04.075

► Prourotensin II is stably folded in acidic buffers containing calcium. ► The proprotein convertases (PC1 and PC2) cleave urotensin II from its precursor. ► Conditions for stable folding coincide with those for optimal cleavage of prourotensin II. ► Stable folding of precursor and optimal cleavage conditions facilitate efficient processing. Proper folding is a crucial step for the trafficking of proteins through the secretory pathway. We hypothesized that the secretory granules of endocrine cells provide optimal folding conditions of prohormone precursors for cleavage. Here, using circular dichroism and in vitro processing on purified prourotensin II (ProUII), we show that the precursor undergoes pH- and Ca2+-dependent conformational and stability changes. ProUII has a stable tertiary structure at pH 5.5 in presence of Ca2+ and is correctly cleaved in these conditions by prohormone convertases. Taken together, our results support the notion that precursors may need to be optimally folded in the lumen of secretory granules for their processing.