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Target cell lysis is regulated by natural killer (NK) cell receptors that recognize class I MHC molecules. Here we report the crystal structure of the human immunoglobulin-like NK cell receptor KIR2DL2 in complex with its class I ligand HLA-Cw3 and peptide. KIR binds in a nearly orthogonal orientation across the alpha1 and alpha2 helices of Cw3 and directly(More)
Kinetoplast DNA (kDNA), the unusual mitochondrial DNA of Trypanosoma brucei, is a network containing thousands of catenated circles. Database searching for a kDNA replicative polymerase (pol) revealed no mitochondrial pol gamma homolog. Instead, we identified four proteins (TbPOLIA, IB, IC, and ID) related to bacterial pol I. Remarkably, all four localized(More)
ATP-dependent protease complexes are present in all living organisms, including the 26S proteasome in eukaryotes, Archaea, and Actinomycetales, and the HslVU protease in eubacteria. The structure of HslVU protease resembles that of the 26S proteasome, and the simultaneous presence of both proteases in one organism was deemed unlikely. However, HslVU(More)
Kinetoplastid protozoa such as trypanosomes and Leishmania are important because they cause human disease. These parasites are named after one of their most unusual features, a mitochondrial DNA known as kinetoplast DNA (kDNA). Unlike all other DNA in nature, kDNA comprises a giant network of interlocked DNA rings with a topology resembling that of medieval(More)
Gene-specific silencing by RNA interference is a valuable tool for analysis of gene function in the protozoan parasite Trypanosoma brucei. The development of tetracycline-regulated vectors for production of double-stranded RNA has facilitated its widespread use. RNA interference provides a fast and efficient method for determining whether a gene is(More)
Fcgamma receptors mediate antibody-dependent inflammatory responses and cytotoxicity as well as certain autoimmune dysfunctions. Here we report the crystal structure of a human Fc receptor (FcgammaRIIIB) in complex with an Fc fragment of human IgG1 determined from orthorhombic and hexagonal crystal forms at 3.0- and 3.5-A resolution, respectively. The(More)
In this review we will describe the replication of kinetoplast DNA, a subject that our lab has studied for many years. Our knowledge of kinetoplast DNA replication has depended mostly upon the investigation of the biochemical properties and intramitochondrial localisation of replication proteins and enzymes as well as a study of the structure and dynamics(More)
Kinetoplast DNA, the mitochondrial DNA of trypanosomatid protozoa, is a network containing several thousand topologically interlocked DNA minicircles. Kinetoplast DNA synthesis involves release of minicircles from the network, replication of the free minicircles, and reattachment of the progeny back onto the network. One enzyme involved in this process is(More)