The motif ExExxxL in the cytosolic tail of the secretory human proprotein convertase PC7 regulates its trafficking and cleavage activity

Loreleï Durand , Stéphanie Duval , Alexandra Evagelidis , Johann Guillemot , Vahid Dianati , Emilia Sikorska , Peter Schu , Robert Day , Nabil G. Seidah

Abstract

Many secretory proteins are activated by cleavage at specific sites. The proprotein convertases (PCs) form a family of nine secretory subtilisin-like serine proteases, seven of which cleave at specific basic residues within the trans-Golgi network (TGN), granules, or at the cell surface/endosomes. The seventh member, PC7, is a type-I transmembrane (TM) protein with a 97-residue-long cytosolic tail (CT). PC7 sheds human transferrin receptor 1 (hTfR1) into soluble shTfR1 in endosomes. To better understand the physiological roles of PC7, here we focused on the relationship between the CT-regulated trafficking of PC7 and its ability to shed hTfR1. Deletion of the TMCT resulted in soluble PC7 and loss of its hTfR1 shedding activity. Extensive CT-deletions and mutagenesis analyses helped us zoom in on three residues in the CT, namely Glu-719, Glu-721, and Leu-725 that are part of a novel motif, ExExxxL725, critical for PC7 activity on hTfR1. NMR studies of two 14-mer peptides mimicking this region of the CT and its Ala variants revealed that the three exposed residues are on the same side of the molecule. This led to the identification of adaptor protein 2 (AP-2) as a protein that recognizes the ExExxxL725 motif, thus representing a potentially new regulator of PC7 trafficking and cleavage activity. Immunocytochemistry of the subcellular localization of PC7 and its Ala variants of Leu-725 and Glu-719 and Glu-721 revealed that Leu-725 enhances PC7 localization to early endosomes and that, together with Glu-719 and Glu-721, it increases the endosomal activity of PC7 on hTfR1.
Publication typeIn press (online first, early view)
Author Loreleï Durand
Loreleï Durand,,
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, Stéphanie Duval
Stéphanie Duval,,
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, Alexandra Evagelidis
Alexandra Evagelidis,,
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, Johann Guillemot
Johann Guillemot,,
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, Vahid Dianati
Vahid Dianati,,
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, Emilia Sikorska (FCh/DOCh/PBSB)
Emilia Sikorska,,
- Pracownia Badań Strukturalnych Biopolimerów
, Peter Schu
Peter Schu,,
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, Robert Day
Robert Day,,
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, Nabil G. Seidah
Nabil G. Seidah,,
-
Journal seriesJournal of Biological Chemistry, ISSN 0021-9258, e-ISSN 1083-351X, (N/A 100 pkt)
Issue year2020
Noonline first
Pages1-35
Publication size in sheets1.70
Keywords in Englishproprotein convertase type 7 (PC7), proprotein convertase subtilisin/kexin type 7 (PCSK7), transferrin receptor 1 (TfR1), cytosolic tail (CT), adaptor protein 2 (AP-2)
ASJC Classification1303 Biochemistry; 1307 Cell Biology; 1312 Molecular Biology
DOIDOI:10.1074/jbc.RA119.011775
URL http://www.jbc.org/content/early/2020/01/08/jbc.RA119.011775.full.pdf
Languageen angielski
LicenseOther; author's final; Other open licence; with publication
Score (nominal)100
Score sourcejournalList
ScoreMinisterial score = 100.0, 03-03-2020, ArticleFromJournal
Publication indicators Scopus SNIP (Source Normalised Impact per Paper): 2018 = 1.064; WoS Impact Factor: 2017 = 4.010 (2) - 2017=4.253 (5)
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