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Chromosome Organization and Cell Growth of Corynebacterium glutamicum

2020; Springer Nature; Linguagem: Inglês

10.1007/978-3-030-39267-3_1

1862-5584

Kati Böhm, Giacomo Giacomelli, Fabian Meyer, Marc Bramkamp,

Genomics and Phylogenetic Studies

Corynebacterineae share an unusually complex cell envelope that discriminates species of this group markedly from other actinobacteria. Phylogenetically, they belong to the Gram-positives, but contain additionally to their peptidoglycan cell wall an extra cell envelope layer composed of arabinose and galactose polymers, the arabinogalactan. Covalently linked to the outer arabinose subunits are mycolic acids forming an inner leaflet of a membrane that is capped by trehalose mono- and dimycolates and forms the mycolic acid membrane, a permeability barrier similar to the outer membrane of Gram-negative bacteria. Like all actinobacteria, Corynebacterium glutamicum grows apically due to a polarly localized elongasome complex. A scaffold protein, DivIVA, is required for spatial organization of the elongasome. Besides organization of elongation growth, DivIVA is also involved in spatial organization of the chromosome. DivIVA serves as an anchor for the partitioning protein ParB that in turn binds DNA sequences in proximity to the origin of replication, thereby orienting the chromosomes to the cell pole. Remarkably, both cell poles contain a stably tethered chromosome, making C. glutamicum diploid. At fast growth conditions, DNA replication can be over-initiated and, hence, polyploidy is common under these conditions. Correct chromosome segregation is key for septum placement, while classical division-site-selection systems seem absent. Recent work unraveled that subcellular organization of Corynebacteria is in many aspects different to that in classical model organisms, indicating the importance to study bacterial species in all their various aspects.