Universität zu Köln

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:	Creators Email ORCID ORCID Put Code Windheim, Mark UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoening, Stefan UNSPECIFIED UNSPECIFIED UNSPECIFIED Leppard, Keith N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Butler, Larissa UNSPECIFIED UNSPECIFIED UNSPECIFIED Seed, Christina UNSPECIFIED UNSPECIFIED UNSPECIFIED Ponnambalam, Sreenivasan UNSPECIFIED orcid.org/0000-0002-4452-7619 UNSPECIFIED Burgert, Hans-Gerhard UNSPECIFIED UNSPECIFIED UNSPECIFIED
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:	Keywords Language AMYLOID PRECURSOR PROTEIN; CLASS-I ANTIGENS; EPIDEMIC KERATOCONJUNCTIVITIS; MOLECULAR EVOLUTION; E3/19K PROTEIN; INFECTED-CELLS; INTRACELLULAR SEQUESTRATION; CLATHRIN ADAPTERS; DOWN-MODULATE; E3 PROTEIN Multiple languages Biochemistry & Molecular Biology Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/28102