Deciphering the interactions between the Bacillus cereus linear plasmid, pBClin15, and its host by high-throughput comparative proteomics

Abstract

Bacteria belonging to the Bacillus cereus group include B. cereus, a notorious food borne pathogen which causes gastroenteritis. The B. cereus type, strain ATCC 14579, harbors a linear plasmid, pBClin15, which displays cryptic prophage behavior. Here, we present data supporting the idea that pBClin15 may have a much greater role in B. cereus metabolism that has hitherto been suspected. Specifically, our comparative proteomic analyses reveal that pBClin15 manages B. cereus central metabolism to optimize energy and carbon utilization through the repression of several chromosome-encoded phage proteins. These results suggest that pBClin15 provides benefit to the host for surviving adverse environmental conditions.

Adaptation in Bacillus cereus: From Stress to Disease

“…Bacillus cereus excretes high level of proteins into the extracellular medium. However, the level of excreted proteins is lower during anaerobic fermentative growth than under aerobic respiratory growth ( Madeira et al, 2016a , b ). Like transcription and translation, exportation of proteins is an energetically expensive process.…”

“…The proteins arising from cellular secretion and other protein export mechanisms are components of the B. cereus exoproteome ( Armengaud et al, 2012 ). B. cereus exoproteome has been the focus of several shotgun proteomic studies ( Clair et al, 2010 , 2013 ; Laouami et al, 2014 ; Madeira et al, 2015 , 2016b ). These proteomic studies identified up to 377 different exoproteins.…”

Methionine Residues in Exoproteins and Their Recycling by Methionine Sulfoxide Reductase AB Serve as an Antioxidant Strategy in Bacillus cereus

“…Wild-type B. cereus ATCC 14579 without its pBClin15 plasmid (Madeira et al, 2016a,b), its Δ msrAB mutant and Δ msrAB /pHT304 msrAB complemented strains were grown in MOD medium supplemented with 30 mM glucose as the carbon source, as previously described (Madeira et al, 2016b). The inoculum was a sample of exponential subculture harvested by centrifugation, washed and diluted in fresh medium to obtain an initial optical density at 600 nm of 0.02.…”

“…The specific growth rate (μ) was determined using the modified Gompertz equation (Zwietering et al, 1990). Cells and filtered culture supernatants were harvested at the indicated growth stage as previously described (Madeira et al, 2015, 2016b). Exoproteins were immediately precipitated from the culture supernatant using trichloroacetic acid (TCA), as previously described, and stored at 4°C until analysis.…”

“…Analyses of changes of peptides and proteins in terms of abundance were achieved by comparing the spectral counts of proteins after voom transformation of abundance values using the R package LIMMA (Ritchie et al, 2015), as previously described (Madeira et al, 2016b). Data were normalized using the trimmed mean of M -values (TMM), implemented in the R package edgeR (Robinson et al, 2010).…”