title: Multifork chromosome replication in slow-growing bacteria.
abstract: The growth rates of bacteria must be coordinated with major cell cycle events, including chromosome replication. When the doubling time (Td) is shorter than the duration of chromosome replication (C period), a new round of replication begins before the previous round terminates. Thus, newborn cells inherit partially duplicated chromosomes. This phenomenon, which is termed multifork replication, occurs among fast-growing bacteria such as Escherichia coli and Bacillus subtilis. In contrast, it was historically believed that slow-growing bacteria (including mycobacteria) do not reinitiate chromosome replication until the previous round has been completed. Here, we use single-cell time-lapse analyses to reveal that mycobacterial cell populations exhibit heterogeneity in their DNA replication dynamics. In addition to cells with non-overlapping replication rounds, we observed cells in which the next replication round was initiated before completion of the previous replication round. We speculate that this heterogeneity may reflect a relaxation of cell cycle checkpoints, possibly increasing the ability of slow-growing mycobacteria to adapt to environmental conditions.
authors.affiliation: Department of Molecular Microbiology, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland.
authors.forename: Damian
authors.initials: D
authors.lastname: Trojanowski
authors.affiliation: Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Hołówka
authors.affiliation: Department of Molecular Microbiology, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland.|Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Ginda
authors.affiliation: Department of Molecular Microbiology, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland.|Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland.
authors.forename: Dagmara
authors.initials: D
authors.lastname: Jakimowicz
authors.affiliation: Department of Molecular Microbiology, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland.|Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Zakrzewska-Czerwińska
mesh_terms: D002455:Cell Division / Q000235:genetics; D002876:Chromosomes, Bacterial / Q000235:genetics*; D004261:DNA Replication; D004269:DNA, Bacterial / Q000235:genetics*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods; D020102:Mycobacterium smegmatis / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D059010:Single-Cell Analysis / Q000379:methods; D059008:Time-Lapse Imaging / Q000379:methods
chemical_list: D004269:DNA, Bacterial; D008164:Luminescent Proteins