Correct positioning of the division plane is a prerequisite for the generation of daughter cells with a normal chromosome complement. Here, we present a mechanism that coordinates assembly and placement of the FtsZ cytokinetic ring with bipolar localization of the newly duplicated chromosomal origins in Caulobacter. After replication of the polarly located origin region, one copy moves rapidly to the opposite end of the cell in an MreB-dependent manner. A previously uncharacterized essential protein, MipZ, forms a complex with the partitioning protein ParB near the origin of replication and localizes with the duplicated origin regions to the cell poles. MipZ directly interferes with FtsZ polymerization, thereby restricting FtsZ ring formation to midcell, the region of lowest MipZ concentration. The cellular localization of MipZ thus serves the dual function of positioning the FtsZ ring and delaying formation of the cell division apparatus until chromosome segregation has initiated.
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http://dx.doi.org/10.1016/j.cell.2006.05.038 | DOI Listing |
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January 2025
D Cohen, Fundación IBYME. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)., Instituto de Biología y Medicina Experimental, Buenos Aires, Argentina.
Artificial oocyte activation (AOA) with Ca2+ ionophores is an experimental procedure that benefits patients who fail to obtain fertilized eggs. However, the impact of non-physiological Ca2+ increases on cellular events involved in egg-embryo transition and early development remains poorly understood. Using the mouse model, this study compares common Ca2+ ionophore protocols applied in clinical practice - one or two exposures to A23187 or a single exposure to ionomycin - focusing on embryonic development and cellular events associated with egg activation.
View Article and Find Full Text PDFUnlabelled: Meiotic chromosome segregation requires reciprocal exchanges between the parental chromosomes (homologs). Exchanges are formed via tightly-regulated repair of double-strand DNA breaks (DSBs). However, since repair intermediates are mostly quantified in fixed images, our understanding of the mechanisms that control the progression of repair remains limited.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Biology, Indiana University, 1001 E 3rd Street, Bloomington, IN 47405, USA.
Genome organization is important for DNA replication, gene expression, and chromosome segregation. In bacteria, two large families of proteins, nucleoid-associated proteins (NAPs) and SMC complexes, play important roles in organizing the genome. NAPs are highly abundant DNA-binding proteins that can bend, wrap, bridge, and compact DNA, while SMC complexes load onto the chromosome, translocate on the DNA, and extrude DNA loops.
View Article and Find Full Text PDFJ Med Virol
January 2025
The Wistar Institute, Philadelphia, Pennsylvania, USA.
Epstein-Barr virus (EBV) is a ubiquitous human ɣ-herpesvirus implicated in various malignancies, including Burkitt's lymphoma and gastric carcinomas. In most EBV-associated cancers, the viral genome is maintained as an extrachromosomal episome by the EBV nuclear antigen-1 (EBNA1). EBNA1 is considered to be a highly stable protein that interacts with the ubiquitin-specific protease 7 (USP7).
View Article and Find Full Text PDFJ Cell Biol
February 2025
Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, USA.
Kinetochores are multiprotein complexes that link chromosomes to microtubules and are essential for chromosome segregation during cell divisions. In this issue, Alves Domingos et al. (https://doi.
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