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Polish Society of Microbiologists

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VOLUME 57 , ISSUE 4 (April 2018) > List of articles


Dawid Gmiter * / Grzegorz Czerwonka / Wiesław Kaca

Keywords : contact-dependent growth inhibition, bacterial competition, type Vb secretion system, type VI secretion system

Citation Information : Postępy Mikrobiologii - Advancements of Microbiology. Volume 57, Issue 4, Pages 360-373, DOI: https://doi.org/10.21307/PM-2018.57.4.360

License : (CC BY-NC-ND 4.0)

Published Online: 24-May-2019



Bacterial competition, defined as a local neighbour interaction, can lead to competitors’ coexistence, bacterial community self-organization or rearrangement of species dominance structure in ecological niches. Bacteria developed many mechanisms to communicate and compete. Kin discrimination mechanisms in bacterial populations allow species to distinguish a friend from a foe in bacterial environment. Type Vb and VI secretion systems (TVIbSS and TVISS) play a crucial role in this phenomenon. A contact-dependent growth inhibition (CDI), primarily found in Escherichia coli strains, utilizes CdiB/CdiA protein of type Vb secretion system, described also as two-partner secretion (TPS) system, to inhibit growth of non-kin strains, where cell contact is required. Presence of an intracellular small immunity protein (CdiI) protects E. coli cells from autoinhibition. Other bacterial competition system, involved mainly in the nodulation process of Rhizobium leguminosarum bv. Trifolii strain, engages type VI secretion system. The structure of TVISS is more complicated and comprises a series of proteins with structural homology to bacteriophage tail proteins and membrane proteins, which build the core of the system (Tss proteins). Other proteins of the TVISS have been described as associated proteins
(Tag proteins). Important proteins for TVISS are also haemolysin coregulated protein (Hcp), which has a hexameric, tubular structure, and VgrG protein (valine-glycine repeat G). VgrG plays a dual role in the process: is a chaperone protein in the secretion of effector toxin or/and is secreted as a toxin itself. Despite the structural differences between these secretion systems, they both show functional homology in the competition phenomenon and govern the social life of bacterial community.

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