Crystal Structure of HLA-A*2402 Complexed with a telomerase peptide
[TERT_HUMAN] Note=Activation of telomerase has been implicated in cell immortalization and cancer cell pathogenesis. Defects in TERT are associated with susceptibilty to aplastic anemia (AA) [MIM:609135]. AA is a rare disease in which the reduction of the circulating blood cells results from damage to the stem cell pool in bone marrow. In most patients, the stem cell lesion is caused by an autoimmune attack. T-lymphocytes, activated by an endogenous or exogenous, and most often unknown antigenic stimulus, secrete cytokines, including IFN-gamma, which would in turn be able to suppress hematopoiesis.    Note=Genetic variations in TERT are associated with coronary artery disease (CAD). Defects in TERT are the cause of dyskeratosis congenita autosomal dominant type 2 (DKCA2) [MIM:613989]. A rare multisystem disorder caused by defective telomere maintenance. It is characterized by progressive bone marrow failure, and the clinical triad of reticulated skin hyperpigmentation, nail dystrophy, and mucosal leukoplakia. Common but variable features include premature graying, aplastic anemia, low platelets, osteoporosis, pulmonary fibrosis, and liver fibrosis among others. Early mortality is often associated with bone marrow failure, infections, fatal pulmonary complications, or malignancy.  Defects in TERT are the cause of pulmonary fibrosis, and/or bone marrow failure, telomere-related, type 1 (PFBMFT1) [MIM:614742]. A disease associated with shortened telomeres. Pulmonary fibrosis is the most common manifestation. Other manifestations include aplastic anemia due to bone marrow failure, hepatic fibrosis, and increased cancer risk, particularly myelodysplastic syndrome and acute myeloid leukemia. Phenotype, age at onset, and severity are determined by telomere length. infections, fatal pulmonary complications, or malignancy.     Defects in TERT are the cause of dyskeratosis congenita autosomal recessive type 4 (DKCB4) [MIM:613989]. A rare multisystem disorder caused by defective telomere maintenance. It is characterized by progressive bone marrow failure, and the clinical triad of reticulated skin hyperpigmentation, nail dystrophy, and mucosal leukoplakia. Common but variable features include premature graying, aplastic anemia, low platelets, osteoporosis, pulmonary fibrosis, and liver fibrosis among others. Early mortality is often associated with bone marrow failure, infections, fatal pulmonary complications, or malignancy. Defects in TERT are a cause of susceptibility to pulmonary fibrosis idiopathic (IPF) [MIM:178500]. Pulmonary fibrosis is a lung disease characterized by shortness of breath, radiographically evident diffuse pulmonary infiltrates, and varying degrees of inflammation and fibrosis on biopsy. It results in acute lung injury with subsequent scarring and endstage lung disease. [B2MG_HUMAN] Defects in B2M are the cause of hypercatabolic hypoproteinemia (HYCATHYP) [MIM:241600]. Affected individuals show marked reduction in serum concentrations of immunoglobulin and albumin, probably due to rapid degradation. Note=Beta-2-microglobulin may adopt the fibrillar configuration of amyloid in certain pathologic states. The capacity to assemble into amyloid fibrils is concentration dependent. Persistently high beta(2)-microglobulin serum levels lead to amyloidosis in patients on long-term hemodialysis.            
[1A24_HUMAN] Involved in the presentation of foreign antigens to the immune system. [TERT_HUMAN] Telomerase is a ribonucleoprotein enzyme essential for the replication of chromosome termini in most eukaryotes. Active in progenitor and cancer cells. Inactive, or very low activity, in normal somatic cells. Catalytic component of the teleromerase holoenzyme complex whose main activity is the elongation of telomeres by acting as a reverse transcriptase that adds simple sequence repeats to chromosome ends by copying a template sequence within the RNA component of the enzyme. Catalyzes the RNA-dependent extension of 3'-chromosomal termini with the 6-nucleotide telomeric repeat unit, 5'-TTAGGG-3'. The catalytic cycle involves primer binding, primer extension and release of product once the template boundary has been reached or nascent product translocation followed by further extension. More active on substrates containing 2 or 3 telomeric repeats. Telomerase activity is regulated by a number of factors including telomerase complex-associated proteins, chaperones and polypeptide modifiers. Modulates Wnt signaling. Plays important roles in aging and antiapoptosis.            [B2MG_HUMAN] Component of the class I major histocompatibility complex (MHC). Involved in the presentation of peptide antigens to the immune system.
Publication Abstract from PubMed
HLA-A*2402 is the most commonly expressed HLA allele in oriental populations. It is also widely expressed in the Caucasian population, making it one of, if not the most abundant HLA I types. In order to study its structure in terms of overall fold and peptide presentation, a soluble form of this HLA I (alpha1, alpha2, alpha3 and beta(2)m domains) has been expressed, refolded and crystallized in complex with a cancer-related telomerase peptide (VYGFVRACL), and its structure has been solved to 2.8 A resolution. The overall structure of HLA-A*2402 is virtually identical to other reported peptide-HLA I structures. However, there are distinct features observable from this structure at the HLA I peptide binding pockets. The size and depth of pocket B makes it highly suitable for binding to large aromatic side chains, which explains the high prevalence of tyrosine at peptide position 2. Also, for HLA binding at peptide position 5, there is an additional anchor point, which allows the proximal amino acids to protrude out, providing a prominent feature for TCR interaction. Finally, pocket F allows the anchor residue at position 9 to be bound unusually deeply within the HLA structure.
Crystal structure of HLA-A*2402 complexed with a telomerase peptide.,Cole DK, Rizkallah PJ, Gao F, Watson NI, Boulter JM, Bell JI, Sami M, Gao GF, Jakobsen BK Eur J Immunol. 2006 Jan;36(1):170-9. PMID:16323248
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.