Contact-Dependent Growth Inhibition in Bacteria: Do Not Get Too Close!

Abstract

Over millions of years of evolution, bacteria have developed complex strategies for intra-and interspecies interactions and competition for ecological niches and resources. Contact-dependent growth inhibition systems (CDI) are designed to realize a direct physical contact of one bacterial cell with other cells in proximity via receptor-mediated toxin delivery. These systems are found in many microorganisms including clinically important human pathogens. The main purpose of these systems is to provide competitive advantages for the growth of the population. In addition, non-competitive roles for CDI toxin delivery systems including interbacterial signal transduction and mediators of bacterial collaboration have been suggested. In this review, our goal was to systematize the recent findings on the structure, mechanisms, and purpose of CDI systems in bacterial populations and discuss the potential biological and evolutionary impact of CDI-mediated interbacterial competition and/or cooperation.

Potential Probiotic Bacillus subtilis Isolated from a Novel Niche Exhibits Broad Range Antibacterial Activity and Causes Virulence and Metabolic Dysregulation in Enterotoxic E. coli

“…For example, Bacillus subtilis have been shown to utilize the CDI secretion system to secrete and deliver toxic polymorphic protein regulatory factors to influence morphological changes and growth inhibition in target strains such as E. coli [49,50]. Contact-dependent growth inhibition is also profoundly used by gram-negative bacteria, such as E. coli, for delivering toxins to the neighbouring target cells [46,51], however, since we did not observe contact inhibition from the ETEC on CP9 in our study may suggest that CDI growth inhibition of ETEC was driven by CP9.…”

Target highlights in CASP14: Analysis of models by structure providers

“…Many Gram‐negative bacteria deploy “contact‐dependent growth inhibition” or “CDI” systems to inhibit the growth of competitors in environmental niches 40,41 . CDI has been characterized extensively in E. coli and other Gram‐negative bacteria, and these systems are particularly common in pathogenic species 41–45 .…”

“…In the case of ring assemblies, although some predictions were reasonably close to the targets, it was surprising to observe noticeable variations regarding ring diameter/orientation, and structure predictions of the monomers within the rings were not as Many Gram-negative bacteria deploy "contact-dependent growth inhibition" or "CDI" systems to inhibit the growth of competitors in environmental niches. 40,41 CDI has been characterized extensively in E. coli and other Gram-negative bacteria, and these systems are particularly common in pathogenic species. [41][42][43][44][45] CDI systems have also been shown to mediate cooperative behaviors-such as biofilm formation, persistence, and virulence-between isogenic sibling cells.…”

A large lipoprotein mediates target specificity for T6SS-dependent killing

“…A variety of interference competition strategies have been described including contact-dependent and diffusible mechanisms [3,4]. Contact-dependent mechanisms require an inhibitor cell to physically interact with a competitor cell to deliver toxic effectors [5][6][7], and such strategies may be particularly useful in liquid environments where diffusible antimicrobial molecules can quickly become diluted.…”