@article {5199, title = {Structure of Cdc4p, a contractile ring protein essential for cytokinesis in Schizosaccharomyces pombe}, journal = {Journal of Biological Chemistry}, volume = {276}, number = {8}, year = {2001}, note = {ISI Document Delivery No.: 404RUTimes Cited: 16Cited Reference Count: 49}, month = {Feb}, pages = {5943-5951}, type = {Article}, abstract = {The Schizosaccharomyces pombe Cdc4 protein is required for the formation and function of the contractile ring, presumably acting as a myosin light chain. By using NMR spectroscopy, we demonstrate that purified Cdc4p is a monomeric protein with two structurally independent domains, each exhibiting a fold reminiscent of the EF-hand class of calcium-binding proteins. Although Cdc4p has one potentially functional calcium-binding site, it does not bind calcium in vitro. Three variants of Cdc4p containing single point mutations responsible for temperature-sensitive arrest of the cell cycle at cytokinesis (Gly-19 to Glu, Gly-82 to Asp, and Gly-107 to Ser) were also characterized by NMR and circular dichroism spectroscopy. In each case, the amino acid substitution only leads to small perturbations in the conformation of the protein. Furthermore, thermal unfolding studies indicate that, like wild-type Cdc4p, the three mutant forms are all extremely stable, remaining completely folded at temperatures significantly above those causing failure of cytokinesis in intact cells. Therefore, the altered phenotype must arise directly from a disruption of the function of Cdc4p rather than indirectly through a disruption of its overall structure. Several mutant alleles of Cdc4p also show interallelic complementation in diploid cells. This phenomenon can be explained if Cdcp4 has more than one essential function or, alternatively, if two mutant proteins assemble to form a functional complex. Based on the structure of Cdc4p, possible models for interallelic complementation including interactions with partner proteins and the formation of a myosin complex with Cdc4p fulfilling the role of both an essential and regulatory light chain are proposed.}, keywords = {BINDING PROTEINS, CALCIUM-SATURATED STATES, ESSENTIAL LIGHT-CHAIN, FISSION YEAST, MYOSIN HEAVY-CHAIN, NUCLEAR-MAGNETIC-RESONANCE, REGULATORY DOMAIN, SCALLOP MYOSIN, TARGETED DISRUPTION, TROPONIN-C}, isbn = {0021-9258}, url = {://000167115100072}, author = {Slupsky, C. M. and Desautels, M. and Huebert, T. and Zhao, R. H. and Hemmingsen, S. M. and McIntosh, L. P.} } @article {4405, title = {Structure of the Ets-1 pointed domain and mitogen-activated protein kinase phosphorylation site}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {95}, number = {21}, year = {1998}, note = {ISI Document Delivery No.: 129DLTimes Cited: 84Cited Reference Count: 37}, month = {Oct}, pages = {12129-12134}, type = {Article}, abstract = {The Pointed (PNT) domain and an adjacent mitogen-activated protein (MAP) kinase phosphorylation site are defined by sequence conservation among a subset of ets transcription factors and are implicated in two regulatory strategies, protein interactions and posttranslational modifications, respectively. By using NMR, we have determined the structure of a 110-residue fragment of murine Ets-1 that includes the PNT domain and MAP kinase site. The Ets-1 PNT domain forms a monomeric five-helix bundle. The architecture is distinct from that of any known DNA- or protein-binding module, including the helix-loop-helix fold proposed for the PNT domain of the ets protein TEL. The MAP kinase site is in a highly flexible region of both the unphosphorylated and phosphorylated forms of the Ets-1 fragment. Phosphorylation alters neither the structure nor monomeric state of the PNT domain. These results suggest that the Ets-1 PNT domain functions in heterotypic protein interactions and support the possibility that target recognition is coupled to structuring of the MAP kinase site.}, keywords = {beta, CHRONIC MYELOMONOCYTIC LEUKEMIA, FUSION, GENE, NMR, OLIGOMERIZATION, TEL, TRANSCRIPTION FACTORS, TRANSLOCATION, TROPONIN-C}, isbn = {0027-8424}, url = {://000076447900013}, author = {Slupsky, C. M. and Gentile, L. N. and Donaldson, L. W. and Mackereth, C. D. and Seidel, J. J. and Graves, B. J. and McIntosh, L. P.} }