C-Terminal Motifs of the MTW1 Complex Cooperatively Stabilize Outer Kinetochore Assembly in Budding Yeast.

Kinetochores are macromolecular protein assemblies at centromeres that mediate accurate chromosome segregation during cell division. The outer kinetochore KNL1, MIS12, and NDC80 complexes assemble the KMN network, which harbors the sites of microtubule binding and spindle assembly checkpoint signaling. The buildup of the KMN network that transmits microtubule pulling forces to budding yeast point centromeres is poorly understood.

CCAN Assembly Configures Composite Binding Interfaces to Promote Cross-Linking of Ndc80 Complexes at the Kinetochore.

Partitioning of the genome requires kinetochores, large protein complexes that mediate dynamic attachment of chromosomes to the spindle. Kinetochores contain two supramolecular protein assemblies. The ten-protein KMN network harbors key microtubule-binding sites in the Ndc80 complex and mediates assembly of checkpoint complexes via the KNL-1/Spc105 protein [1, 2].

Architecture and RNA binding of the human negative elongation factor.

Transcription regulation in metazoans often involves promoter-proximal pausing of RNA polymerase (Pol) II, which requires the 4-subunit negative elongation factor (NELF). Here we discern the functional architecture of human NELF through X-ray crystallography, protein crosslinking, biochemical assays, and RNA crosslinking in cells. We identify a NELF core subcomplex formed by conserved regions in subunits NELF-A and NELF-C, and resolve its crystal structure.

xVis: a web server for the schematic visualization and interpretation of crosslink-derived spatial restraints.

The identification of crosslinks by mass spectrometry has recently been established as an integral part of the hybrid structural analysis of protein complexes and networks. The crosslinking analysis determines distance restraints between two covalently linked amino acids which are typically summarized in a table format that precludes the immediate and comprehensive interpretation of the topological data. xVis displays crosslinks in clear schematic representations in form of a circular, bar or network diagram.

A cooperative mechanism drives budding yeast kinetochore assembly downstream of CENP-A.

Kinetochores are megadalton-sized protein complexes that mediate chromosome-microtubule interactions in eukaryotes. How kinetochore assembly is triggered specifically on centromeric chromatin is poorly understood. Here we use biochemical reconstitution experiments alongside genetic and structural analysis to delineate the contributions of centromere-associated proteins to kinetochore assembly in yeast.

The pseudo GTPase CENP-M drives human kinetochore assembly.

Kinetochores, multi-subunit complexes that assemble at the interface with centromeres, bind spindle microtubules to ensure faithful delivery of chromosomes during cell division. The configuration and function of the kinetochore-centromere interface is poorly understood. We report that a protein at this interface, CENP-M, is structurally and evolutionarily related to small GTPases but is incapable of GTP-binding and conformational switching.

Structure of the VipA/B type VI secretion complex suggests a contraction-state-specific recycling mechanism.

The bacterial type VI secretion system is a multicomponent molecular machine directed against eukaryotic host cells and competing bacteria. An intracellular contractile tubular structure that bears functional homology with bacteriophage tails is pivotal for ejection of pathogenic effectors. Here, we present the 6 Å cryoelectron microscopy structure of the contracted Vibrio cholerae tubule consisting of the proteins VipA and VipB.

Spatiotemporal regulation of Ipl1/Aurora activity by direct Cdk1 phosphorylation.

Oscillating cyclin-dependent kinase 1 (Cdk1) activity is the major regulator of cell-cycle progression, whereas the Aurora B kinase, as part of the chromosome passenger complex (CPC), controls critical aspects of mitosis such as chromosome condensation and biorientation on the spindle. How these kinases mechanistically coordinate their important functions is only partially understood. Here, using budding yeast, we identify a regulatory mechanism by which the Cdk1 kinase Cdc28 directly controls the Aurora kinase Ipl1.

Phosphoregulation of the budding yeast EB1 homologue Bim1p by Aurora/Ipl1p.

EB1 (end binding 1) proteins have emerged as central regulators of microtubule (MT) plus ends in all eukaryotes, but molecular mechanisms controlling the activity of these proteins are poorly understood. In this study, we show that the budding yeast EB1 protein Bim1p is regulated by Aurora B/Ipl1p-mediated multisite phosphorylation. Bim1p forms a stable complex with Ipl1p and is phosphorylated on a cluster of six Ser residues in the flexible linker connecting the calponin homology (CH) and EB1 domains.