title: Asymmetric growth and division in Mycobacterium spp.: compensatory mechanisms for non-medial septa.
abstract: Mycobacterium spp., rod-shaped cells belonging to the phylum Actinomycetes, lack the Min- and Noc/Slm systems responsible for preventing the placement of division sites at the poles or over the nucleoids to ensure septal assembly at mid-cell. We show that the position for establishment of the FtsZ-ring in exponentially growing Mycobacterium marinum and Mycobacterium smegmatis cells is nearly random, and that the cells often divide non-medially, producing two unequal but viable daughters. Septal sites and cellular growth disclosed by staining with the membrane-specific dye FM4-64 and fluorescent antibiotic vancomycin (FL-Vanco), respectively, showed that many division sites were off-centre, often over the nucleoids, and that apical cell growth was frequently unequal at the two poles. DNA transfer through the division septum was detected, and translocation activity was supported by the presence of a putative mycobacterial DNA translocase (MSMEG2690) at the majority of the division sites. Time-lapse imaging of single live cells through several generations confirmed both acentric division site placement and unequal polar growth in mycobacteria. Our evidence suggests that post-septal DNA transport and unequal polar growth may compensate for the non-medial division site placement in Mycobacterium spp.
authors: Department of Cell and Molecular Biology, Uppsala University Biomedical Center, Box 596, 751 24 Uppsala, Sweden.
authors: Bhupender
authors: B
authors: Singh
authors: Ram Gopal
authors: RG
authors: Nitharwal
authors: Malavika
authors: M
authors: Ramesh
authors: B M Fredrik
authors: BM
authors: Pettersson
authors: Leif A
authors: LA
authors: Kirsebom
authors: Santanu
authors: S
authors: Dasgupta
mesh_terms: D060049:Asymmetric Cell Division; D002453:Cell Cycle; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D004269:DNA, Bacterial / Q000378:metabolism; D009161:Mycobacterium / Q000166:cytology* / Q000254:growth & development* / Q000648:ultrastructure; D033704:Nucleotide Transport Proteins / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D033704:Nucleotide Transport Proteins