Structural and functional dissection of an MHC class I antigen-binding adenovirus glycoprotein.

Abstract

The early transmembrane glycoprotein E19 of adenovirus-2 binds to class I antigens of the major histocompatibility complex (MHC). The association is initiated in the endoplasmic reticulum of infected cells and abrogates the intracellular transport of the class I molecules. To examine which parts of the E19 molecule are responsible for the association with the class I antigens and which parts confine the protein to the endoplasmic reticulum we have constructed a series of mutated E19 genes, which have been expressed in an improved mammalian expression vector. By various manipulations the membrane anchoring and the cytoplasmic domains were removed from the protein. The biosynthesis of the mutant protein was exanined. All mutant proteins were secreted from the cells suggesting that the transmembrane and/or cytoplasmic portions of the E19 molecule are responsible for its confinement to the endoplasmic reticulum. The ability to associate with class I antigens was retained by the lumenal domain of the E19 protein.

Structural analysis of the adenovirus type 2 E3/19K protein using mutagenesis and a panel of conformation-sensitive monoclonal antibodies

“…The association between E3/19K and MHC class I molecules is non-covalent and does neither require N-linked carbohydrates, present at amino acid positions 12 and 61 in Ad2 E3/19K Kornfeld and Wold, 1981) nor its cytoplasmic tail (Cox et al, 1991;Pääbo et al, 1987;Pääbo et al, 1986b). The transmembrane segment might be necessary for HLA interaction within the cell but is not required in vitro (Gabathuler et al, 1990;Liu et al, 2005;Pääbo et al, 1986b).…”

“…The transmembrane segment might be necessary for HLA interaction within the cell but is not required in vitro (Gabathuler et al, 1990;Liu et al, 2005;Pääbo et al, 1986b). Hence, the interaction is primarily mediated by the lumenal portion of E3/19K (Hermiston et al, 1993;Liu et al, 2005;Pääbo et al, 1986b;Sester and Burgert, 1994) which contains two intramolecular disulfide bonds that are absolutely critical for HLA binding (Sester and Burgert 1994).…”

“…The transmembrane segment might be necessary for HLA interaction within the cell but is not required in vitro (Gabathuler et al, 1990;Liu et al, 2005;Pääbo et al, 1986b). Hence, the interaction is primarily mediated by the lumenal portion of E3/19K (Hermiston et al, 1993;Liu et al, 2005;Pääbo et al, 1986b;Sester and Burgert, 1994) which contains two intramolecular disulfide bonds that are absolutely critical for HLA binding (Sester and Burgert 1994). Using hybrid MHC molecules containing domains from E3/19K-binding and non-binding MHC alleles, the polymorphic peptide binding domains 1 and 2 of MHC molecules have been shown to be critical for complex formation with E3/19K (Beier et al, 1994;Feuerbach et al, 1994;Jefferies and Burgert, 1990).…”

Conserved Amino Acids within the Adenovirus 2 E3/19K Protein Differentially Affect Downregulation of MHC Class I and MICA/B Proteins

“…Although the interaction does not require the cytoplasmic tail of E3/19K (21,50,51), the transmembrane segment might be critical for HLA-I interaction in vivo within the cell but is not essential in vitro (38,51,52). Hence, the interaction is primarily mediated by the luminal portion of E3/19K (30,38,51,53).…”

“…Hence, the interaction is primarily mediated by the luminal portion of E3/19K (30,38,51,53). This suspicion was confirmed by the complete loss of HLA-I binding upon disruption in the luminal domain of the two intramolecular disulfide bonds (30) and by construction of in-frame deletions (53).…”