title: Mutation of Serine 32 to Threonine in Peroxiredoxin 6 Preserves Its Structure and Enzymatic Function but Abolishes Its Trafficking to Lamellar Bodies.
abstract: Peroxiredoxin 6 (Prdx6), a bifunctional protein with phospholipase A2 (aiPLA2) and GSH peroxidase activities, protects lungs from oxidative stress and participates in lung surfactant phospholipid turnover. Prdx6 has been localized to both cytosol and lamellar bodies (LB) in lung epithelium, and its organellar targeting sequence has been identified. We propose that Prdx6 LB targeting facilitates its role in the metabolism of lung surfactant phosphatidylcholine (PC). Ser-32 has been identified as the active site in Prdx6 for aiPLA2 activity, and this activity was abolished by the mutation of serine 32 to alanine (S32A). However, aiPLA2 activity was unaffected by mutation of serine 32 in Prdx6 to threonine (S32T). Prdx6 protein expression and aiPLA2 activity were normal in the whole lung of a "knock-in" mouse model carrying an S32T mutation in the Prdx6 gene but were absent from isolated LB. Analyses by proximity ligation assay in lung sections demonstrated the inability of S32T Prdx6 to bind to the chaperone protein, 14-3-3ϵ, that is required for LB targeting. The content of total phospholipid, PC, and disaturated PC in lung tissue homogenate, bronchoalveolar lavage fluid, and lung LB was increased significantly in Prdx6-S32T mutant lungs, whereas degradation of internalized [(3)H]dipalmitoyl-PC was significantly decreased. Thus, Thr can substitute for Ser for the enzymatic activities of Prdx6 but not for its targeting to LB. These results confirm an important role for LB Prdx6 in the degradation and remodeling of lung surfactant phosphatidylcholine.
authors.affiliation: From the Institute for Environmental Medicine, Department of Physiology, and.
authors.forename: Elena M
authors.initials: EM
authors.lastname: Sorokina
authors.affiliation: From the Institute for Environmental Medicine, Department of Physiology, and.
authors.forename: Chandra
authors.initials: C
authors.lastname: Dodia
authors.affiliation: From the Institute for Environmental Medicine, Department of Physiology, and.
authors.forename: Suiping
authors.initials: S
authors.lastname: Zhou
authors.affiliation: From the Institute for Environmental Medicine, Department of Physiology, and.
authors.forename: Jian-Qin
authors.initials: JQ
authors.lastname: Tao
authors.affiliation: From the Institute for Environmental Medicine, Department of Physiology, and.
authors.forename: Ling
authors.initials: L
authors.lastname: Gao
authors.affiliation: Penn Gene Targeting Core and Laboratory, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
authors.forename: Tobias
authors.initials: T
authors.lastname: Raabe
authors.affiliation: From the Institute for Environmental Medicine, Department of Physiology, and.
authors.forename: Sheldon I
authors.initials: SI
authors.lastname: Feinstein
authors.affiliation: From the Institute for Environmental Medicine, Department of Physiology, and abf@mail.med.upenn.edu.
authors.forename: Aron B
authors.initials: AB
authors.lastname: Fisher
mesh_terms: D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D002460:Cell Line; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D020125:Mutation, Missense; D054465:Peroxiredoxin VI / Q000235:genetics / Q000378:metabolism; D010713:Phosphatidylcholines / Q000096:biosynthesis* / Q000235:genetics; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000235:genetics; D011663:Pulmonary Surfactants / Q000378:metabolism*; D020545:Respiratory Mucosa / Q000201:enzymology*
chemical_list: D048948:14-3-3 Proteins; D010713:Phosphatidylcholines; D011663:Pulmonary Surfactants; C482983:YWHAE protein, human; C576823:Ywhae protein, mouse; C515977:PRDX6 protein, human; D054465:Peroxiredoxin VI; C515983:Prdx6 protein, mouse
keywords: 14-3-3 protein; lung; peroxiredoxin; phospholipase A; phospholipid metabolism