Here we investigate this question by inserting the known fibril-forming segment NNQQNY into the globular enzyme, T7 endonuclease I. From earlier studies, we know that in its fibril form, NNQQNY is in an extended conformation.

We first found that the inserted NNQQNY stimulates fibril formation of T7 endonuclease I in solution. Thus NNQQNY within T7 endonuclease I can exist in an extended conformation, capable of forming the steric zipper in the core of a fibril. We also found that T7 endonuclease I folds into a decamer that does not form fibrils. We determined the structure of the decamer by X-ray crystallography, finding an unusual oligomer without point group symmetry, and finding that the NNQQNY segments within the decamer adopt two twisted conformations, neither is apparently Selleck Pritelivir able to fibrillize. We conclude that twisting of fibril forming sequences from the fully extended conformation, imposed by the context of their placement in proteins, can interfere with fibril formation.”
“The find more purpose of these studies was to identify human leukocyte antigen (HLA)-A2(+) immunogenic peptides derived from

XBP1 antigens to induce a multiple myeloma (MM)-specific immune response. Six native peptides from non-spliced XBP1 antigen and three native peptides from spliced XBP1 antigen were selected and evaluated for their HLA-A2 specificity. Among them, XBP1(184-192), XBP1 SP196-204 and XBP1 SP367-375 peptides showed the highest level of binding affinity, but not stability to HLA-A2 molecules. Novel heteroclitic XBP1 peptides, YISPWILAV or YLFPQLISV, demonstrated a significant improvement in HLA-A2 stability from their native XBP1(184-192) or XBP1 SP367-375 peptide, respectively. Cytotoxic T lymphocytes generated by repeated

stimulation of CD3(+) T cells with each HLA-A2-specific heteroclitic peptide showed an increased percentage of CD8(+) (cytotoxic) and CD69(+)/ CD45RO(+) (activated SC75741 ic50 memory) T cells and a lower percentage of CD4(+) (helper) and CD45RA(+)/CCR7(+) (naive) T cells, which were distinct from the control T cells. Functionally, the cytotoxic T lymphocytes (CTL) demonstrated MM-specific and HLA-A2-restricted proliferation, interferon-gamma secretion and cytotoxic activity in response to MM cell lines and importantly, cytotoxicity against primary MM cells. These data demonstrate the distinct immunogenic characteristics of unique heteroclitic XBP1 peptides, which induce MM-specific CTLs and highlights their potential application for immunotherapy to treat the patients with MM or its pre-malignant condition. Leukemia (2011) 25, 1610-1619; doi:10.1038/leu.2011.