A functionally defective allele of TAP1 results in loss of MHC class I antigen presentation in a human lung cancer

Chen, Hailei L.; Gabrilovich, Dmitry I.; Tampé, Robert; Girgis, Khaled R.; Nadaf, Sorena; Carbone, David P.

doi:10.1038/ng0696-210

Cited by 178 publications

(94 citation statements)

References 13 publications

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“…Whatever the reason for the limited effect of the T1R659Q mutation on TAP transport and B27 expression, a 50% function by T1R659Q mutant TAP proteins is a surprising finding, given that the human small cell lung cancer line H1436, in which the mutation was found, was described as essentially "HLA class I negative" (16). Several explanations may account for this discrepancy.…”

Section: Discussionmentioning

confidence: 67%

“…Inversion of the carboxyl-terminal Ser-Thr residues (mutants T1ST545/6TS and T2ST510/1TS) has been reported to enhance efficiency of MgATP utilization by the cystic fibrosis transmembrane conductance regulator (CFTR) (25). Finally, mutation T1R659Q corresponds to a natural mutation in the TAP1 Walker B motif previously identified in a human small cell lung cancer line and was described to be associated with a TAPdeficient cell phenotype (16). Replacements of entire Walker A motifs by synthetic linker peptides (mutants T1Rep and T2Rep), or complete Walker A deletions (mutants T1Del and T2Del) were included to study TAP proteins highly likely to be unable to hydrolyze and bind ATP.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, similar to the CFTR (25), mutation T1ST545/6TS may enhance efficiency of ATP hydrolysis by TAP1. Surprisingly, mutation T1R659Q, reported to create a TAP-deficient cell phenotype (16), reduced peptide accumulation by about 50% rather than abolishing it. ATP-independent peptide accumulation after prolonged microsome incubation at 37°C is likely to reflect vesicle "leakiness."…”

Section: Peptide Translocation and Supply To Hla-b27 Molecules Bymentioning

confidence: 99%

“…Thus, diminution or loss of TAP function plays a role in the pathogenesis of viral and malignant diseases. These perturbations of TAP function may be related to mutations or protein interactions interfering with ATP metabolism; indeed, a case of a human lung tumor with impaired TAP function because of a mutation in the Walker B region has been described (16).…”

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confidence: 99%

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Distinct Functions of the ATP Binding Cassettes of Transporters Associated with Antigen Processing

Saveanu

Daniel

Endert

2001

Journal of Biological Chemistry

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The transporters associated with antigen processing (TAP1/TAP2) provide peptides to MHC class I molecules in the endoplasmic reticulum. Like other ATP-binding cassette proteins, TAP uses ATP hydrolysis to power transport. We have studied peptide binding to as well as translocation by TAP proteins with mutations in the Walker A and B sequences that are known to mediate ATP binding and hydrolysis. We show that a mutation in the TAP1 Walker B sequence reported to abrogate class I expression by a lung tumor does not affect ATP binding affinity, suggesting a defect restricted to ATP hydrolysis. This mutation reduces peptide transport by only 50%, suggesting that TAP function can be highly limiting for antigen presentation in non-lymphoid cells. Single substitutions in Walker A sequences (TAP1K544A, TAP2K509A), or their complete replacements, abrogate nucleotide binding to each subunit. Although all of these mutations abrogate peptide transport, they reveal distinct roles for nucleotide binding to the two transporter subunits in TAP folding and in regulation of peptide substrate affinity, respectively. Alteration of the TAP1 Walker A motif can have strong effects on TAP1 and thereby TAP complex folding. However, TAP1 Walker A mutations compatible with correct folding do not affect peptide binding. In contrast, abrogation of the TAP2 nucleotide binding capacity has little or no effect on TAP folding but eliminates peptide binding to TAP at 37°C in the presence of nucleotides. Thus, nucleotide binding to TAP2 but not to TAP1 is a prerequisite for peptide binding to TAP. Based on these results, we propose a model in which nucleotide and peptide release from TAP are coupled and followed by ATP binding to TAP2, which induces high peptide affinity and initiates the transport cycle.The transporters associated with antigen processing (TAP) 1 belong to the family of ATP binding cassette (ABC) transporters, a large group of proteins that use energy provided by nucleotide triphosphates to translocate a vast variety of substrates across intracellular or cell surface membranes (1). All ABC transporters possess two transmembrane domains, each generally composed of six membrane-spanning segments, and two nucleotide binding domains (NBDs) with primary sequence homology across the protein family. Whereas substrate interaction is generally thought to involve the transmembrane domains, the NBDs bind and hydrolyze ATP. Both of the latter events have been shown to lead to conformational changes that upon transmission to substrate binding domains in an undefined fashion result in substrate translocation (2).Given the important role of ABC transporters in diseases such as mucoviscidosis or cancer, the mechanism of substrate transport has been subject to intense scrutiny. Mutagenesis studies and crystallographic analysis of HisP and MalK, the NBDs of bacterial histidine and maltose transporters, respectively, have elucidated the role of several conserved sequence motifs contained in ABC transporter NBDs (3, 4). Thus, the Walker A consensus s...

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Section: Discussionmentioning

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Section: Peptide Translocation and Supply To Hla-b27 Molecules Bymentioning

confidence: 99%

mentioning

confidence: 99%

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Distinct Functions of the ATP Binding Cassettes of Transporters Associated with Antigen Processing

Saveanu

Daniel

Endert

2001

Journal of Biological Chemistry

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“…Both NDBs bind ATP when expressed separately, but they do not hydrolyze ATP (19,20). Both ATP-binding sites need to be functional, because mutation of TAP1 NBD leads to a loss of transport function (21). However, the NBDs are used not only for energizing peptide translocation but also for synchronizing the entire process of peptide translocation, loading, and dissociation of MHC molecules from the TAP complex (22).…”

mentioning

confidence: 99%

Allosteric crosstalk between peptide-binding, transport, and ATP hydrolysis of the ABC transporter TAP

Gorbulev

Abele

Tampé

2001

Proc. Natl. Acad. Sci. U.S.A.

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116

114

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The transporter associated with antigen processing (TAP) is essential for intracellular transport of protein fragments into the endoplasmic reticulum for loading of major histocompatibility complex (MHC) class I molecules. On the cell surface, these peptide-MHC complexes are monitored by cytotoxic T lymphocytes. To study the ATP hydrolysis of TAP, we developed an enrichment and reconstitution procedure, by which we fully restored TAP function in proteoliposomes. A TAPspecific ATPase activity was identified that could be stimulated by peptides and blocked by the herpes simplex virus protein ICP47. Strikingly, the peptide-binding motif of TAP directly correlates with the stimulation of the ATPase activity, demonstrating that the initial peptide-binding step is responsible for TAP selectivity. ATP hydrolysis follows Michaelis-Menten kinetics with a maximal velocity V max of 2 mol͞min per mg TAP, corresponding to a turnover number of approximately 5 ATP per second. This turnover rate is sufficient to account for the role of TAP in peptide loading of MHC molecules and the overall process of antigen presentation. Interestingly, sterically restricted peptides that bind but are not transported by TAP do not stimulate ATPase activity. These results point to coordinated dialogue between the peptide-binding site, the nucleotide-binding domain, and the translocation site via conformational changes within the TAP complex.membrane proteins ͉ transport mechanism ͉ ATPase ͉ antigen processing A n essential step in the major histocompatibility complex (MHC) class I-mediated cellular immune defense is the transport of antigenic peptides from the cytoplasm into the endoplasmic reticulum (ER) (reviewed by ref. 1). The transporter associated with antigen processing (TAP) translocates peptides that are mainly derived from the proteasomal degradation into the ER (reviewed by ref. 2). Subsequently, peptides bind to MHC class I molecules and are presented at the cell surface, where they are recognized by cytotoxic T lymphocytes.TAP belongs to the family of ATP-binding cassette (ABC) transporters that, under consumption of ATP, translocate a vast spectrum of substrates across membranes (3). On the basis of sequence comparison, TAP fits in the B subfamily of human ABC transporters (www.gene.ucl.ac.uk͞users͞hester͞abc.html), including the well-characterized P-glycoprotein (ABCB1). The TAP complex forms a heterodimer of TAP1 (ABCB2) and TAP2 (ABCB3), where each subunit comprises a hydrophobic transmembrane domain and a cytoplasmic nucleotide-binding domain (NBD) containing the Walker A͞B and C-loop consensus sequences. The transmembrane domains are thought to form a channel by which peptides are transported across the ER membrane driven by ATP hydrolysis. The coupling between NBDs, the substrate-binding site, and the translocation pathway is not understood and is a central topic to be studied for all ABC transporters.TAP is part of a macromolecular peptide translocation and loading complex that comprises TAP1, TAP2, tapasin, MHC class I hea...

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Heterogeneity in expression of human leukocyte antigens and melanoma-associated antigens in advanced melanoma

Ohnmacht

Marincola

2000

J. Cell. Phys.

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The study of tumor immunology has led to many innovative therapeutic strategies for the treatment of melanoma. The strategies are primarily dependent on melanoma-associated antigen peptide vaccination or T-cell-based therapy. These immunotherapies are totally reliant on proper copresentation of human leukocyte antigen class I molecules in sufficient quantity and the presence and availability of melanoma-associated antigenic peptides. Altered expression of either HLA class I molecules or melanoma antigens is known to occur. These defects lead to altered manufacture and copresentation of HLA class I molecules with melanoma-associated antigens to T-cells. Defects in any one combination can lead to loss of recognition of melanoma cells and their subsequent destruction by cytotoxic T-lymphocytes. Thus, these immunotherapy strategies can be thwarted by defects or heterogeneity of expression of human leukocyte antigen class I or of melanoma-associated antigens.

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A functionally defective allele of TAP1 results in loss of MHC class I antigen presentation in a human lung cancer

Cited by 178 publications

References 13 publications

Distinct Functions of the ATP Binding Cassettes of Transporters Associated with Antigen Processing

Distinct Functions of the ATP Binding Cassettes of Transporters Associated with Antigen Processing

Allosteric crosstalk between peptide-binding, transport, and ATP hydrolysis of the ABC transporter TAP

Heterogeneity in expression of human leukocyte antigens and melanoma-associated antigens in advanced melanoma

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