Pseudomonas aeruginosa Contact-Dependent Growth Inhibition Plays Dual Role in Host-Pathogen Interactions

Abstract

How bacteria compete and communicate with each other is an increasingly recognized aspect of microbial pathogenesis with a major impact on disease outcomes. Gram-negative bacteria have recently been shown to employ a contact-dependent toxin-antitoxin system to achieve both competition and regulation of their physiology. Here, we show that this system is vital for virulence in acute infection as well as for establishment of chronic infection in the multidrug-resistant pathogen Pseudomonas aeruginosa. Greater understanding of the mechanisms underlying bacterial virulence and infection is important for the development of effective therapeutics in the era of increasing antimicrobial resistance.

Movers and shakers: Bumble bee foraging behavior shapes the dispersal of microbes among and within flowers

“…, Melvin et al. ). To track microbial dispersal, we transformed P. fluorescens SBW25 with a plasmid (pSMC21) that constitutively expresses GFP through electroporation following Bloemberg et al.…”

“…To study pollinator-mediated microbial dispersal among flowers, we used P. fluorescens, a bacterium commonly found on plants, related to Pseudomonas spp. isolated from flowers and pollinators, used in managed apivectoring to flowers, and readily transformable according to established literature (Johnson et al 1993, Ganeshan and Kumar 2005, Pusey et al 2009, McFrederick et al 2012, Aleklett et al 2014, Melvin et al 2017. To track microbial dispersal, we transformed P. fluorescens SBW25 with a plasmid (pSMC21) that constitutively expresses GFP through electroporation following Bloemberg et al (1997).…”

“…This plasmid contains a rhlA::gfp transcriptional fusion and confers resistance against carbenicillin (the selective marker). The plasmid is stable for at least several days in P. fluorescens in the absence of antibiotic selection (Bloemberg et al 1997, Melvin et al 2017. We cultured the strain in sterile tryptic soy broth and 100 mg/L carbenicillin in a shaker at 28°C and 200 rpm for 24 h. The strain was thereafter transferred to 1.5-mL sterile microcentrifuge tubes (Fisher Scientific, Hampton, New Hampshire, USA) and put through two rounds of centrifuging (9.6g for 5 min) and sterile saline (8.5% NaCl) substitution and elimination to purge media.…”

Target highlights in CASP13: Experimental target structures through the eyes of their authors

“…To protect themselves from self‐intoxication, CDI + cells also produce a CdiI immunity protein that binds the CdiA‐CT to neutralize toxin activity. Though characterized most extensively in E. coli , CDI systems are broadly distributed throughout Gram‐negative bacteria including pathogens and have been implicated in cooperative behaviors, such as biofilm formation, persistence, and virulence . CdiA effectors carry extraordinarily diverse CdiA‐CT regions, indicating that the systems deploy many distinct toxins.…”

“…Though characterized most extensively in E. coli, CDI systems are broadly distributed throughout Gram-negative bacteria including pathogens 35 and have been implicated in cooperative behaviors, such as biofilm formation, persistence, and virulence. [36][37][38] CdiA effectors carry extraordinarily diverse CdiA-CT regions, indicating that the systems deploy many distinct toxins. Similarly, CdiI sequences are also highly variable, and each immunity protein only provides protection against its cognate toxin.…”