Mycoplasmas are no exception to extracellular vesicles release: Revisiting old concepts

Abstract

Release of extracellular vesicles (EV) by Gram-negative and positive bacteria is being frequently reported. EV are nano-sized, membrane-derived, non-self-replicating, spherical structures shed into the extracellular environment that could play a role in bacteria-host interactions. Evidence of EV production in bacteria belonging to the class Mollicutes, which are wall-less, is mainly restricted to the genus Acholeplasma and is scanty for the Mycoplasma genus that comprises major human and animal pathogens. Here EV release by six Mycoplasma (sub)species of clinical importance was investigated. EV were obtained under nutritional stress conditions, purified by ultracentrifugation and observed by electron microscopy. The membrane proteins of EV from three different species were further identified by mass spectrometry as a preliminary approach to determining their potential role in host-pathogen interactions. EV were shown to be released by all six (sub)species although their quantities and sizes (30–220 nm) were very variable. EV purification was complicated by the minute size of viable mycoplasmal cells. The proteins of EV-membranes from three (sub)species included major components of host-pathogen interactions, suggesting that EV could contribute to make the host-pathogen interplay more complex. The process behind EV release has yet to be deciphered, although several observations demonstrated their active release from the plasma membrane of living cells. This work shed new light on old concepts of “elementary bodies” and “not-cell bound antigens”.

Proteases as Secreted Exoproteins in Mycoplasmas from Ruminant Lungs and Their Impact on Surface-Exposed Proteins

“…Its ratio within the pellet samples was quite stable, whichever mycoplasma strain was studied, with a mean of 6.7 ϫ 10 Ϫ3 (n ϭ 15; minimum ϭ 4.5 ϫ 10 Ϫ3 ; maximum ϭ 8.5 ϫ 10 Ϫ3 ) and a supernatant/pellet fold change level which ranged from 0.04 to 0.7, an indication that FtsH was detected mostly in the cell pellet. This preliminary analysis confirmed that our procedure for sample preparation did not induce a noticeable level of release of membrane fragments in the supernatant attributable due to cell lysis or vesicle formation (21). In contrast, a number of proteases were highly expressed and detected both in the pellet and in the supernatant (0.5-fold to 2.5-fold change).…”

The Diverse Functional Roles of Elongation Factor Tu (EF-Tu) in Microbial Pathogenesis

“…EF-Tu is present within MVs derived from Gram-positive bacteria including Listeria monocytogenes (Coelho et al, 2019), Mycobacterium bovis , Mycobacterium smegmatis , Mycobacterium tuberculosis (Prados-Rosales et al, 2011), Staphylococcus aureus (Lee et al, 2009; Wang et al, 2018), Streptococcus agalactiae (Surve et al, 2016), Streptococcus pnuemoniae (Olaya-Abril et al, 2014), and Streptococcus pyogenes (Resch et al, 2016); Gram-negative bacteria including Acinetobacter baumannii (Kwon et al, 2009), Bacteroides fragilis (Zakharzhevskaya et al, 2017), Cronobacter sakazakii (Alzahrani et al, 2015), Escherichia coli (Lee et al, 2007), Francisella novicida (Pierson et al, 2011), Haemophilus influenzae (Sharpe et al, 2011), Klebsiella pneumoniae (Lee et al, 2012), Neisseria gonorrhoeae (Pérez-Cruz et al, 2015), Neisseria meningitidis (Vipond et al, 2006), and Pseudomonas aeruginosa (Choi et al, 2011); and in six Mycoplasma species (Gaurivaud et al, 2018). Indeed, EF-Tu was reported as one of the most abundant protein in some of these studies (Lee et al, 2009; Pérez-Cruz et al, 2015; Gaurivaud et al, 2018). Interestingly, several MVs that contain EF-Tu have been reported to increase virulence (Surve et al, 2016), modulate immune responses (Prados-Rosales et al, 2011; Sharpe et al, 2011; Alzahrani et al, 2015), and offer protection to infection via immunization (Vipond et al, 2006; Pierson et al, 2011; Olaya-Abril et al, 2014).…”

Role of Extracellular Vesicles in Influenza Virus Infection

“…and even physiological or pathological environment of donor cells or tissues including hypoxia, hyperthermia, infections, circadian rhythms, hormones, and stage of cell cycle, etc. (Burger et al, 2017 ; Németh et al, 2017 ; Gaurivaud et al, 2018 ; Ludwig et al, 2019 ; Pegtel and Gould, 2019 ; Kalluri and LeBleu, 2020 ; Zubair et al, 2020 ). Moreover, the existing isolation and purification technologies (e.g., ultracentrifugation, nanoscale flow cytometry, immunoprecipitation/affinity capture, Exosome Isolation Reagent, etc.)…”