Windheim, Mark, Hoening, Stefan, Leppard, Keith N., Butler, Larissa, Seed, Christina, Ponnambalam, Sreenivasan ORCID: 0000-0002-4452-7619 and Burgert, Hans-Gerhard (2016). Sorting Motifs in the Cytoplasmic Tail of the Immunomodulatory E3/49K Protein of Species D Adenoviruses Modulate Cell Surface Expression and Ectodomain Shedding. J. Biol. Chem., 291 (13). S. 6796 - 6813. BETHESDA: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC. ISSN 1083-351X

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Abstract

The E3 transcription unit of human species C adenoviruses (Ads) encodes immunomodulatory proteins that mediate direct protection of infected cells. Recently, we described a novel immunomodulatory function for E3/49K, an E3 protein uniquely expressed by species D Ads. E3/49K of Ad19a/Ad64, a serotype that causes epidemic keratokonjunctivitis, is synthesized as a highly glycosylated type I transmembrane protein that is subsequently cleaved, resulting in secretion of its large ectodomain (sec49K). sec49K binds to CD45 on leukocytes, impairing activation and functions of natural killer cells and T cells. E3/49K is localized in the Golgi/trans-Golgi network (TGN), in the early endosomes, and on the plasma membrane, yet the cellular compartment where E3/49K is cleaved and the protease involved remained elusive. Here we show that TGN-localized E3/49K comprises both newly synthesized and recycled molecules. Full-length E3/49K was not detected in late endosomes/lysosomes, but the C-terminal fragment accumulated in this compartment at late times of infection. Inhibitor studies showed that cleavage occurs in a post-TGN compartment and that lysosomotropic agents enhance secretion. Interestingly, the cytoplasmic tail of E3/49K contains two potential sorting motifs, YXX phi (where phi represents a bulky hydrophobic amino acid) and LL, that are important for binding the clathrin adaptor proteins AP-1 and AP-2 in vitro. Surprisingly, mutating the LL motif, either alone or together with YXX phi, did not prevent proteolytic processing but increased cell surface expression and secretion. Upon brefeldin A treatment, cell surface expression was rapidly lost, even for mutants lacking all known endocytosis motifs. Together with immunofluorescence data, we propose a model for intracellular E3/49K transport whereby cleavage takes place on the cell surface by matrix metalloproteases.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Windheim, MarkUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hoening, StefanUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Leppard, Keith N.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Butler, LarissaUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Seed, ChristinaUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ponnambalam, SreenivasanUNSPECIFIEDorcid.org/0000-0002-4452-7619UNSPECIFIED
Burgert, Hans-GerhardUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-281022
DOI: 10.1074/jbc.M115.684787
Journal or Publication Title: J. Biol. Chem.
Volume: 291
Number: 13
Page Range: S. 6796 - 6813
Date: 2016
Publisher: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Place of Publication: BETHESDA
ISSN: 1083-351X
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
AMYLOID PRECURSOR PROTEIN; CLASS-I ANTIGENS; EPIDEMIC KERATOCONJUNCTIVITIS; MOLECULAR EVOLUTION; E3/19K PROTEIN; INFECTED-CELLS; INTRACELLULAR SEQUESTRATION; CLATHRIN ADAPTERS; DOWN-MODULATE; E3 PROTEINMultiple languages
Biochemistry & Molecular BiologyMultiple languages
Refereed: Yes
URI: http://kups.ub.uni-koeln.de/id/eprint/28102

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