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Asymmetric growth and division in M ycobacterium spp.: compensatory mechanisms for non‐medial septa
Author(s) -
Singh Bhupender,
Nitharwal Ram Gopal,
Ramesh Malavika,
Pettersson B. M. Fredrik,
Kirsebom Leif A.,
Dasgupta Santanu
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12169
Subject(s) - biology , ftsz , cell division , nucleoid , translocase , microbiology and biotechnology , division (mathematics) , chromosomal translocation , cell , genetics , gene , escherichia coli , arithmetic , mathematics
Summary M ycobacterium spp., rod‐shaped cells belonging to the phylum A ctinomycetes, 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 M ycobacterium marinum and M ycobacterium 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 ‐ V anco), 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 M ycobacterium spp.