Investigation of theListeria monocytogenesScott A Acid Tolerance Response and Associated Physiological and Phenotypic Features via Whole Proteome Analysis

Abstract

The global proteomic responses of the foodborne pathogen Listeria monocytogenes strain Scott A, during active growth and transition to the stationary growth phase under progressively more acidic conditions, created by addition of lactic acid and HCl, were investigated using label-free liquid chromatography/tandem mass spectrometry. Approximately 56% of the Scott A proteome was quantitatively assessable, and the data provides insight into its acquired acid tolerance response (ATR) as well as the relation of the ATR to the growth phase transition. Alterations in protein abundance due to acid stress were focused in proteins belonging to the L. monocytogenes common genome, with few strain-dependent proteins involved. However, one of the two complete prophage genomes appeared to enter lysogeny. During progressive acidification, the growth rate and yield were reduced 55% and 98%, respectively, in comparison to nonacidified control cultures. The maintenance of the growth rate was determined to be connected to activation of cytoplasmic pH homeostatic mechanisms while cellular reproductive-related and cell component turnover proteins were markedly more abundant in acid stressed cultures. Cell biomass accumulation was impeded predominantly due to repression of phosphodonor-linked enzymes involved with sugar phosphotransfer, glycolysis, and cell wall polymer biosynthesis. Acidification caused a shift from heterofermentation to an oxidatively stressed state in which ATP appears to be generated mainly through the pyruvate dehydrogenase/pyruvate oxidase/phosphotransacetylase/acetate kinase and branched chain acid dehydrogenase pathways. Analysis of regulons indicated energy conservation occurs due to repression by the GTP/isoleucine sensor CodY and also the RelA mediated stringent response. Whole proteome analysis proved to be an effective way to highlight proteins involved with the acquisition of the ATR.

Proteomics analysis of Listeria monocytogenes ATCC 19115 in response to simultaneous triple stresses

“…Previous studies have carried out proteomics analyses of L. monocytogenes exposed to single-or dual-stress (cold, acid and salt) conditions (Cacace et al 2010;Bowman et al 2012;Pittman et al 2014). However, the response of the proteome of L. monocytogenes to simultaneous exposure to cold, acid and salt had not been investigated and was therefore examined in the present study.…”

“…In E. coli, Suf and Isc can both assemble Fe-S clusters, but the Suf pathway is the better choice under oxidative stress and iron starvation conditions (Ayala-Castro et al 2008). Previous studies have also discovered that cold, salt or acid stress enhances the expression of several iron-sulfur assembly proteins in L. monocytogenes (Cacace et al 2010;Bowman et al 2012;Pittman et al 2014). In conclusion, the expression of iron-sulfur cluster assembly proteins of L. monocytogenes was induced under triple stresses, suggesting that Suf system was also activated to meet the demand for maintaining Fe-S cluster assembly under oxidative stress conditions.…”

“…3), leading to the accumulation of pyruvate. On the contrary, single stresses, such as cold, acid or salt, increased the levels of the pleiotropic repressor CodY in the cells, presumably to repress energy-consuming processes for cellular energy conservation (Bowman et al 2012;Durack et al 2013).…”

“…Proteomics strategies have been applied to better understand the mechanisms of how L. monocytogenes responds to cold, heat, acidic, salt, alkali, detergent and redox stresses, respectively (Phan-Thanh and Gormon 1997; Duche et al 2002;Giotis et al 2008;Agoston et al 2009;Cacace et al 2010;Bowman et al 2012;Ignatova et al 2013). The response to cold, acid or salt stress mainly affects the biochemical processes related to oxidative stress, nutrient uptake and transcriptional regulation (Cacace et al 2010;Bowman et al 2012;Duche et al 2002).…”

“…The response to cold, acid or salt stress mainly affects the biochemical processes related to oxidative stress, nutrient uptake and transcriptional regulation (Cacace et al 2010;Bowman et al 2012;Duche et al 2002). Additionally, the metabolism of pathogen in response to stress can be adapted through reconstruction of metabolic pathways and formation of de novo end-products, such as lipid, Abstract Listeria monocytogenes can cause listeriosis in humans through consumption of contaminated food.…”