3ln5
From Proteopedia
Crystal structure of HLA-B*4104 in complex with a 11mer self-peptide derived from S-methyl-5-thioadenosine phosphorylase
Structural highlights
Disease[MTAP_HUMAN] Defects in MTAP are the cause of diaphyseal medullary stenosis with malignant fibrous histiocytoma (DMSMFH) [MIM:112250]. An autosomal dominant bone dysplasia characterized by pathologic fractures due to abnormal cortical growth and diaphyseal medullary stenosis. The fractures heal poorly, and there is progressive bowing of the lower extremities. Some patients show a limb-girdle myopathy, with muscle weakness and atrophy. Approximately 35% of affected individuals develop an aggressive form of bone sarcoma consistent with malignant fibrous histiocytoma or osteosarcoma. Note=DMSMFH causing mutations found in MTAP exon 9 result in exon skipping and dysregulated alternative splicing of all MTAP isoforms (PubMed:22464254).[1] Note=Loss of MTAP activity may play a role in human cancer. MTAP loss has been reported in a number of cancers, including osteosarcoma, malignant melanoma and gastric cancer.[HAMAP-Rule:MF_03155] [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.[2] 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.[3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] Function[1B41_HUMAN] Involved in the presentation of foreign antigens to the immune system. [MTAP_HUMAN] Catalyzes the reversible phosphorylation of S-methyl-5'-thioadenosine (MTA) to adenine and 5-methylthioribose-1-phosphate. Involved in the breakdown of MTA, a major by-product of polyamine biosynthesis. Responsible for the first step in the methionine salvage pathway after MTA has been generated from S-adenosylmethionine. Has broad substrate specificity with 6-aminopurine nucleosides as preferred substrates.[16] [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 PubMedAbstract Background. Polymorphic differences between human leucocyte antigen (HLA) molecules affect the specificity and conformation of their bound peptides and lead to differential selection of the T-cell repertoire. Mismatching during allogeneic transplantation can therefore lead to immunological reactions. Design and methods. We investigated the structure-function relationships of six members of the HLA-B*41 allelic group that differ by six polymorphic amino acids, including positions 80, 95, 97 and 114 within the antigen binding cleft. Peptide-binding motifs for B*4101, *4102, *4103, *4104, *4105 and *4106 were determined by sequencing self-peptides from recombinant B*41 molecules by ESI-MS-MS fragmentation. The crystal structures of HLA-B*4103 bound to a natural 16-mer self-ligand (AEMYGSVTEHPSPSPL) and HLA-B*4104 bound to a natural 11-mer self-ligand (HEEAVSVDRVL) were solved. Results. Peptide analysis revealed that all B*41 alleles have an identical p2 anchor (Glu), but differ in their choice of C-terminal p_anchor (Pro, Val, Leu). Additionally, B*4104 displayed a greater preference for long peptides (>10 residues) when compared to the other B*41 allomorphs, while the longest peptide to be eluted from the allelic group (a 16mer) was obtained from B*4103. The crystal structures of HLA-B*4103 and HLA-B*4104 revealed that both alleles interact in a highly conserved manner with the terminal regions of their respective ligands, while micropolymorphism-induced changes in the steric and electrostatic properties of the Ag-binding cleft account for differences in peptide repertoire and auxiliary anchoring. Conclusions. Differences in peptide repertoire, and peptide length specificity reflect the significant functional evolution of these closely related allotypes and signal their importance in allogeneic transplantation, especially B*4103 and B*4104, which accommodate longer peptides, creating structurally distinct pHLA-I (peptide-HLA) ligands. The impact of human leucocyte antigen (HLA) micropolymorphism on ligand specificity within the HLA-B*41 allotypic family.,Bade-Doeding C, Theodossis A, Gras S, Kjer-Nielsen L, Eiz-Vesper B, Seltsam A, Huyton T, Rossjohn J, McCluskey J, Blasczyk R Haematologica. 2010 Oct 7. PMID:20934997[17] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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