Each sample corresponded to the same number of isolated chromosomes. A, Chromosomes, histone-depleted mitotic chromosomes, or histone-enriched (soluble) fraction isolated with (+) or without (−) 1% β-mercaptoethanol (βME) from DT40 cells were analyzed by immunoblotting using antibodies against SMC2, Top2A, or INCENP and Coomassie Brilliant Blue (CBB) staining for core histones. Proteomics of proteins concentrated in the mitotic chromosome scaffold. Further characterization of the functional role of BAZ1 proteins would provide new insights into the timing of chromosome condensation.Ĭell Biology Cell Cycle Cell Division Chromatin Function or Biology Chromosome Mitosis SILAC. Our results suggest that BAZ1 proteins are essential for timely chromosome condensation at mitosis entry. Knocking out BAZ1B caused prophase delay because of altered chromosome condensation timing and mitosis progression errors, and the effect was aggravated if BAZ1A, a BAZ1B homolog, was simultaneously knocked out however, protein composition of prometaphase chromosomes was normal. MS revealed a novel component of the chromosome scaffold, bromodomain adjacent to zinc finger 1B (BAZ1B), which was localized to the mitotic chromosome axis. We used the DT40 chicken cell line to isolate mitotic chromosomes and extract the associated protein fraction, which could contain the chromosome scaffold. The aim of this study was to determine the protein composition of the chromosome scaffold. The components of the chromosome scaffold, such as DNA topoisomerase IIα (TOP2A) and structural maintenance of chromosomes protein 2 (SMC2), are necessary to generate stable mitotic chromosomes however, the existence of this scaffold remains controversial. A classical model for mitotic chromosome condensation proposes that non-histone proteins act as a structural framework called the chromosome scaffold. and B.C.).In mitosis, chromosomes achieve their characteristic shape through condensation, an essential process for proper segregation of the genome during cell division. and B.C.) and European Research Council grant 716058 (K.M.C. and B.C.) Swiss National Center of Competence in Chemical Biology (K.M.C. and B.C.) Swiss National Center of Competence for Molecular Systems Engineering (K.M.C. and J.-H.C.) Swiss National Science Foundation (K.M.C. and D.T.) Amgen (S.L.) the Human Frontier Science Program Cross Disciplinary Fellowship (LT000395/2020-C) and EMBO Non-Stipendiary Fellowship (ALTF 1047-2019) (L.F.M.) the EMBO Fellowship (ALTF 191-2021) (T.S.) European Molecular Biology Organization Grant (ALTF 139-2018) (B.I.M.W.) the “la Caixa” Foundation (M.E.) the National Institute of Allergy and Infectious Diseases (NIAID) Federal Contract HHSN272201700059C (I.A.), NIH grant DP5OD026389 (S.O.) the National Science Foundation MCB 2032259 (S.O.) the Howard Hughes Medical Institute (D.B., R.R., and K.M.C.), the National Institute on Aging grant 5U19AG065156 (D.B., J.L.W., D.R.H., and M.E.) the National Cancer Institute grant R01CA240339 (D.B. and W.Y.) the DARPA Harnessing Enzymatic Activity for Lifesaving Remedies project HR001120S0052 contract HR-0012 (N.B.) the Washington Research Foundation (J.W.) the Open Philanthropy Project Improving Protein Design Fund (D.B. and J.D.) Eric and Wendy Schmidt by recommendation of the Schmidt Futures (D.J.) the DARPA Synergistic Discovery and Design project HR001117S0003 contract FA8750-17-C-0219 (D.B. This work was supported with funds provided by the Audacious Project at the Institute for Protein Design (D.B. Wicky, Andrew Muenks, Frank DiMaio, Bruno Correia, Sergey Ovchinnikov, and David Baker Show Fewerįunding: We thank Microsoft for support and for providing Azure computing resources. Hicks, Marc Expòsit, Thomas Schlichthaerle, Jung-Ho Chun, Justas Dauparas, Nathaniel Bennett, Basile I. Milles, Minkyung Baek, Ivan Anishchenko, Wei Yang, Derrick R. Castro, Robert Ragotte, … Show All …, Amijai Saragovi, Lukas F. Jue Wang, Sidney Lisanza, David Juergens, Doug Tischer, Joseph L.
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