Shugoshin is an evolutionarily conserved protein, which is involved in tension sensing on mitotic chromosomes, kinetochore biorientation, and protection of centromeric (CEN) cohesin for faithful chromosome segregation. Interaction of the C-terminus of Sgo1 with phosphorylated histone H2A regulates its association with CEN and pericentromeric (peri-CEN) chromatin, whereas mutations in histone H3 selectively compromise the association of Sgo1 with peri-CEN but not CEN chromatin. Given that histone H3 is absent from CEN and is replaced by a histone H3 variant CENP-A, we investigated if CENP-A interacts with Sgo1 and promotes its association with the CEN chromatin. In this study, we found that Sgo1 interacts with CENP-A in vivo and in vitro. The N-terminus coiled-coil domain of Sgo1 without the C-terminus (sgo1-NT) is sufficient for its interaction with CENP-A, association with CEN but not the peri-CEN, and this CEN association is cell cycle dependent with maximum enrichment in mitosis. In agreement with the role of CENP-A in CEN maintenance of Sgo1, depletion of CENP-A results in the loss of Sgo1 and sgo1-NT from the CEN chromatin. The N-terminus of Sgo1 is required for genome stability as a mutant lacking the N-terminus (sgo1-CT) exhibits increased chromosome missegregation when compared to a sgo1-NT mutant. In summary, our results define a novel role for the N-terminus of Sgo1 in CENP-A mediated recruitment of Sgo1 to CEN chromatin for faithful chromosome segregation.

Protein α-N-methylation is an underexplored post-translational modification involving the covalent addition of methyl groups to the free α-amino group at protein N-termini. To systematically explore the extent of α-N-terminal methylation in yeast and humans, we reanalyzed publicly accessible proteomic datasets to identify N-terminal peptides contributing to the α-N-terminal methylome. This repurposing approach found evidence of α-N-methylation of established and novel protein substrates with canonical N-terminal motifs of established α-N-terminal methyltransferases, including human NTMT1/2 and yeast Tae1. NTMT1/2 are implicated in cancer and aging processes but have unclear and context-dependent roles. Moreover, α-N-methylation of noncanonical sequences was surprisingly prevalent, suggesting unappreciated and cryptic methylation events. Analysis of the amino acid frequencies of α-N-methylated peptides revealed a [S]1-[S/A/Q]2 pattern in yeast and [A/N/G]1-[A/S/V]2-[A/G]3 in humans, which differs from the canonical motif. We delineated the distribution of the two types of prevalent N-terminal modifications, acetylation and methylation, on amino acids at the first position. We tested three potentially methylated proteins and confirmed the α-N-terminal methylation of Hsp31 by additional proteomic analysis and immunoblotting. The other two proteins, Vma1 and Ssa3, were found to be predominantly acetylated, indicating that proteomic searching for α-N-terminal methylation requires careful consideration of mass spectra. This study demonstrates the feasibility of reprocessing proteomic data for global α-N-terminal methylome investigations.

Aging is characterized by changes in several cellular processes, including dysregulation of proteostasis. Current research has shown long‐lived rodents display elevated proteasome activity throughout life and proteasome dysfunction is linked to shorter lifespans in a transgenic mouse model. The ubiquitin proteasome system (UPS) is one of the main pathways leading to cellular protein clearance and quality maintenance. Reduction in proteasome activity is associated with aging and its related pathologies. Small molecule stimulators of the proteasome have been proposed to help alleviate cellular stress related to unwanted protein accumulation. Here we have described the development of techniques to monitor the impact of proteasome stimulation in wild‐type yeast and a strain that has impaired proteasome expression. We validated our chronological lifespan assay using both types of yeast with a variety of small molecule stimulators at different concentrations. By modifying the media conditions for the yeast, molecules can be evaluated for their potential to increase chronological lifespan in five days. Additionally, our assay conditions can be used to monitor the activity of proteasome stimulators in modulating the degradation of a YFP‐α‐synuclein fusion protein produced by yeast. We anticipate these methods to be valuable for those wishing to study the impact of increasing proteasome‐mediated degradation of proteins in a eukaryotic model organism.

Any field could be severely impacted by occasional stern crises. Therefore, having appropriate strategies to not only survive from the predicaments but also achieve subsequent long-term prosperity will be crucial. In this paper, Delta will be exemplified to show its successful tactics for disentangling its bankruptcy crisis that happened in 2005. The author will primarily illustrate and evaluate in two parts-the reasons that triggered its bankruptcy and the stratagems they used to exit-basically from the start of it filed bankruptcy in 2005 to the exit in 2007. In addition , through data analysis to show the importance of cost structure for a company, this paper is also meant to provide references for those companies which are on the edge of bankrupt after the coronavirus period.