Defining the response of a microorganism to temperatures that span its complete growth temperature range (−2°C to 28°C) using multiplex quantitative proteomics

Abstract

The growth of all microorganisms is limited to a specific temperature range. However, it has not previously been determined to what extent global protein profiles change in response to temperatures that incrementally span the complete growth temperature range of a microorganism. As a result it has remained unclear to what extent cellular processes (inferred from protein abundance profiles) are affected by growth temperature and which, in particular, constrain growth at upper and lower temperature limits. To evaluate this, 8-plex iTRAQ proteomics was performed on the Antarctic microorganism, Methanococcoides burtonii. Methanococcoides burtonii was chosen due to its importance as a model psychrophilic (cold-adapted) member of the Archaea, and the fact that proteomic methods, including subcellular fractionation procedures, have been well developed. Differential abundance patterns were obtained for cells grown at seven different growth temperatures (-2°C, 1°C, 4°C, 10°C, 16°C, 23°C, 28°C) and a principal component analysis (PCA) was performed to identify trends in protein abundances. The multiplex analysis enabled three largely distinct physiological states to be described: cold stress (-2°C), cold adaptation (1°C, 4°C, 10°C and 16°C), and heat stress (23°C and 28°C). A particular feature of the thermal extremes was the synthesis of heat- and cold-specific stress proteins, reflecting the important, yet distinct ways in which temperature-induced stress manifests in the cell. This is the first quantitative proteomic investigation to simultaneously assess the response of a microorganism to numerous growth temperatures, including the upper and lower growth temperatures limits, and has revealed a new level of understanding about cellular adaptive responses.

Microbial ecology of an Antarctic hypersaline lake: genomic assessment of ecophysiology among dominant haloarchaea

“…The production of extracellular polymeric substances (EPS) and biofilm formation has been observed for certain strains of tADL and H. lacusprofundi, with N-acetylglucosamine and/or sialic acid identified as constituent glycoconjugates (Frö ls et al, 2012). EPS promote cell aggregation and biofilm formation of archaea at low temperatures (Reid et al, 2006;Allen et al, 2009;Williams et al, 2011). As well as facilitating adhesion to solid surfaces, EPS is also inferred to serve in protection against desiccation, osmotic stress and phage attack (Sutherland, 2001).…”

On the concept of a psychrophile

“…Problems with the concept of a psychrophile have arisen because of the tendency for many in the field to use temperature-dependent growth rate as a measure for assessing how well adapted a microorganism is to the cold (see discussion in Brenchley, 1996;Feller and Gerday, 2003;Bakermans and Nealson, 2004;Cavicchioli and Siddiqui, 2004;Goodchild et al, 2004;Cavicchioli, 2006;Ting et al, 2010;Williams et al, 2011;Lauro et al, 2011a). This is a false guide because, when temperature increases, enzyme reaction rates increase as a result of the kinetic effect of heat, and microbial growth rates increase until some process in the cell becomes thermally compromised.…”

“…This includes assessments of growth yield, viability, level of enzyme secretion, protein synthesis, membrane permeability and stress markers (see discussion and papers cited in Brenchley, 1996;Feller and Gerday, 2003;Bakermans and Nealson, 2004;Cavicchioli and Siddiqui, 2004;Goodchild et al, 2004;Cavicchioli, 2006;Ting et al, 2010;Williams et al, 2011;Lauro et al, 2011a). Functional 'omic' studies canvass changes in global gene expression and provide a broad level of insight into cellular responses.…”

Draft Genome Sequence of a Psychrotolerant Sulfur-Oxidizing Bacterium, Sulfuricella denitrificans skB26, and Proteomic Insights into Cold Adaptation

“…Similarly, a 20-fold increase was observed for the ribosomal protein L7/L12 in LT, and 6 ribosomal proteins were identified only in LT. The protein L7/L12 has been reported to be a cold acclimation protein (6), and increased ribosomal protein abundance at low temperatures has been observed in other prokaryotes (11,33). The high cellular levels of ribosomal proteins observed in S. denitrificans may be associated with cold adaptation.…”