Novel role of zinc-finger protein 518 in heterochromatin formation on α-satellite DNA.

Aneuploidy is caused by chromosomal missegregation and is frequently observed in cancers and hematological diseases. Therefore, it is important to understand the molecular mechanisms underlying chromosomal segregation. The centromere's intricate structure is crucial for proper chromosome segregation, with heterochromatin at the pericentromeric α-satellites playing a key role.

A role for condensin-mediator interaction in mitotic chromosomal organization.

Eukaryotic genomes are organized by condensin into 3D chromosomal architectures suitable for chromosomal segregation during mitosis. However, molecular mechanisms underlying the condensin-mediated chromosomal organization remain largely unclear. Here, we investigate the role of newly identified interaction between the Cnd1 condensin and Pmc4 mediator subunits in fission yeast, Schizosaccharomyces pombe.

Chemo-Senolytic Therapeutic Potential against Angiosarcoma.

Angiosarcoma is an aggressive soft-tissue sarcoma with a poor prognosis. Chemotherapy for this cancer typically employs paclitaxel, a taxane (genotoxic drug), although it has a limited effect owing to chemoresistance to prolonged treatment. In this study, we examine an alternative angiosarcoma treatment approach that combines chemotherapeutic and senolytic agents.

CCDC86 is a novel Ki-67-interacting protein important for cell division.

The chromosome periphery is a network of proteins and RNAs that coats the outer surface of mitotic chromosomes. Despite the identification of new components, the functions of this complex compartment are poorly characterised. In this study, we identified a novel chromosome periphery-associated protein, CCDC86 (also known as cyclon).

HP1α targets the chromosomal passenger complex for activation at heterochromatin before mitotic entry.

The chromosomal passenger complex (CPC) is directed to centromeres during mitosis via binding to H3T3ph and Sgo1. Whether and how heterochromatin protein 1α (HP1α) influences CPC localisation and function during mitotic entry is less clear. Here, we alter HP1α dynamics by fusing it to a CENP-B DNA-binding domain.

Nano Random Forests to mine protein complexes and their relationships in quantitative proteomics data.

Ever-increasing numbers of quantitative proteomics data sets constitute an underexploited resource for investigating protein function. Multiprotein complexes often follow consistent trends in these experiments, which could provide insights about their biology. Yet, as more experiments are considered, a complex's signature may become conditional and less identifiable.

Identification of Mitosis-Specific Phosphorylation in Mitotic Chromosome-Associated Proteins.

During mitosis, phosphorylation of chromosome-associated proteins is a key regulatory mechanism. Mass spectrometry has been successfully applied to determine the complete protein composition of mitotic chromosomes, but not to identify post-translational modifications. Here, we quantitatively compared the phosphoproteome of isolated mitotic chromosomes with that of chromosomes in nonsynchronized cells.

Dual Emission and Mechanofluorochromism of a V-Shaped π-System Composed of Disulfonyl-Substituted Dibenzocyclooctatetraenes.

A series of dibenzocyclooctatetraenes 6 bearing phenylethynyl and phenylsulfonyl groups were synthesized from bromo-substituted formylbenzyl sulfone 4 via cyclic dimerization of 4 and Sonogashira coupling of the resulting dibromocyclooctatetraene 3 with terminal acetylenes. The diamino derivative 6b exhibited dual emission with emission maxima at 436 and 547 nm. Furthermore, in the fluorescence of 6b, solvatofluorochromism was observed in response to solvent polarity, whereas in the solid states, mechanofluorochromism was observed.

Proteomics Analysis with a Nano Random Forest Approach Reveals Novel Functional Interactions Regulated by SMC Complexes on Mitotic Chromosomes.

Packaging of DNA into condensed chromosomes during mitosis is essential for the faithful segregation of the genome into daughter nuclei. Although the structure and composition of mitotic chromosomes have been studied for over 30 years, these aspects are yet to be fully elucidated. Here, we used stable isotope labeling with amino acids in cell culture to compare the proteomes of mitotic chromosomes isolated from cell lines harboring conditional knockouts of members of the condensin (SMC2, CAP-H, CAP-D3), cohesin (Scc1/Rad21), and SMC5/6 (SMC5) complexes.

Auxin/AID versus conventional knockouts: distinguishing the roles of CENP-T/W in mitotic kinetochore assembly and stability.

Most studies using knockout technologies to examine protein function have relied either on shutting off transcription (conventional conditional knockouts with tetracycline-regulated gene expression or gene disruption) or destroying the mature mRNA (RNAi technology). In both cases, the target protein is lost at a rate determined by its intrinsic half-life. Thus, protein levels typically fall over at least 1-3 days, and cells continue to cycle while exposed to a decreasing concentration of the protein.

Polyglutamylated Tubulin Binding Protein C1orf96/CSAP Is Involved in Microtubule Stabilization in Mitotic Spindles.

The centrosome-associated C1orf96/Centriole, Cilia and Spindle-Associated Protein (CSAP) targets polyglutamylated tubulin in mitotic microtubules (MTs). Loss of CSAP causes critical defects in brain development; however, it is unclear how CSAP association with MTs affects mitosis progression. In this study, we explored the molecular mechanisms of the interaction of CSAP with mitotic spindles.

CENP-32 is required to maintain centrosomal dominance in bipolar spindle assembly.

Centrosomes nucleate spindle formation, direct spindle pole positioning, and are important for proper chromosome segregation during mitosis in most animal cells. We previously reported that centromere protein 32 (CENP-32) is required for centrosome association with spindle poles during metaphase. In this study, we show that CENP-32 depletion seems to release centrosomes from bipolar spindles whose assembly they had previously initiated.

Mitotic chromosomes are compacted laterally by KIF4 and condensin and axially by topoisomerase IIα.

Mitotic chromosome formation involves a relatively minor condensation of the chromatin volume coupled with a dramatic reorganization into the characteristic "X" shape. Here we report results of a detailed morphological analysis, which revealed that chromokinesin KIF4 cooperated in a parallel pathway with condensin complexes to promote the lateral compaction of chromatid arms. In this analysis, KIF4 and condensin were mutually dependent for their dynamic localization on the chromatid axes.

The protein composition of mitotic chromosomes determined using multiclassifier combinatorial proteomics.

Despite many decades of study, mitotic chromosome structure and composition remain poorly characterized. Here, we have integrated quantitative proteomics with bioinformatic analysis to generate a series of independent classifiers that describe the approximately 4,000 proteins identified in isolated mitotic chromosomes. Integrating these classifiers by machine learning uncovers functional relationships between protein complexes in the context of intact chromosomes and reveals which of the approximately 560 uncharacterized proteins identified here merits further study.

Defining lipid-binding regions of human serum amyloid A using its fragment peptides.

Human serum amyloid A (SAA) protein is an apolipoprotein predominantly present in the high-density lipoprotein fraction of plasma. Despite its critical roles in lipid metabolism, especially in acute phases, systematic understanding of the lipid interaction of this protein is limited. Lipid-binding properties of synthetic fragment peptides corresponding to the N-terminal (residues 1-27), central (residues 43-63), and C-terminal (residues 77-104) parts of SAA molecule were examined.

Evaluation of lipid-binding properties of the N-terminal helical segments in human apolipoprotein A-I using fragment peptides.

Although the N-terminal region in human apolipoprotein (apo) A-I is thought to stabilize the lipid-free structure of the protein, its role in lipid binding is unknown. Using synthetic fragment peptides, we examined the lipid-binding properties of the first 43 residues (1-43) of apoA-I in comparison with residues 44-65 and 220-241, which have strong lipid affinity in the molecule. Circular dichroism measurements demonstrated that peptides corresponding to each segment have potential propensity to form alpha-helical structure in trifluoroethanol.

Molecular and genetic analysis of condensin function in vertebrate cells.

We engineered mutants into residues of SMC2 to dissect the role of ATPase function in the condensin complex. These residues are predicted to be involved in ATP binding or hydrolysis and in the Q-loop, which is thought to act as a mediator of conformational changes induced by substrate binding. All the engineered ATPase mutations resulted in lethality when introduced into SMC2 null cells.

Contributions of the N- and C-terminal helical segments to the lipid-free structure and lipid interaction of apolipoprotein A-I.

The tertiary structure of lipid-free apolipoprotein (apo) A-I in the monomeric state comprises two domains: a N-terminal alpha-helix bundle and a less organized C-terminal domain. This study examined how the N- and C-terminal segments of apoA-I (residues 1-43 and 223-243), which contain the most hydrophobic regions in the molecule and are located in opposite structural domains, contribute to the lipid-free conformation and lipid interaction. Measurements of circular dichroism in conjunction with tryptophan and 8-anilino-1-naphthalenesulfonic acid fluorescence data demonstrated that single (L230P) or triple (L230P/L233P/Y236P) proline insertions into the C-terminal alpha helix disrupted the organization of the C-terminal domain without affecting the stability of the N-terminal helix bundle.

Involvement of two domains with helix-turn-helix and zinc finger motifs in the binding of IS1 transposase to terminal inverted repeats.

The insertion element IS1 has two open reading frames (ORFs), insA and insB, and produces a transframe protein InsAB, known as IS1 transposase, by translational frameshifting. The transposase binds to terminal inverted repeats (IRL and IRR) to promote IS1 transposition. Unless frameshifting occurs, IS1 produces InsA protein, which also binds to IRs and therefore acts as an inhibitor of transposition, as well as a transcriptional repressor of the promoter in IRL.

A novel IS element, IS621, of the IS110/IS492 family transposes to a specific site in repetitive extragenic palindromic sequences in Escherichia coli.

An Escherichia coli strain, ECOR28, was found to have insertions of an identical sequence (1,279 bp in length) at 10 loci in its genome. This insertion sequence (named IS621) has one large open reading frame encoding a putative protein that is 326 amino acids in length. A computer-aided homology search using the DNA sequence as the query revealed that IS621 was homologous to the piv genes, encoding pilin gene invertase (PIV).

Titanium alkoxide complex of functionalized conjugated dienes. A versatile bis-anionic template for stereoselective construction of carbon frameworks.

1,3-Butadiene-2-carboxylates were treated with a titanium(II) alkoxide reagent, Ti(O-i-Pr)4/2i-PrMgCl, to generate diene-titanium alkoxide complexes, the presence of which was verified by hydrolysis and deuteriolysis to give the corresponding monoolefins or their bis-deuterated counterpart. These diene complexes underwent successive addition to an aldehyde (as the first electrophile) and iodine (as the second one) in a highly regio- and stereoselective manner to give the corresponding iodo alcohol. Optically active 1,3-butadiene-2-carboxylates afforded the same adducts of high asymmetric induction.

Presence of a characteristic D-D-E motif in IS1 transposase.

Transposases encoded by various transposable DNA elements and retroviral integrases belong to a family of proteins with three conserved acidic amino acids, D, D, and E, constituting the D-D-E motif that represents the active center of the proteins. IS1, one of the smallest transposable elements in bacteria, encodes a transposase which has been thought not to belong to the family of proteins with the D-D-E motif. In this study, we found several IS1 family elements that were widely distributed not only in eubacteria but also in archaebacteria.