Changes in the Vibrio harveyi Cell Envelope Subproteome During Permanence in Cold Seawater

Abstract

Previous work demonstrated that physiological, morphological, and gene expression changes as well as the time-dependent entry into the viable but not culturable (VBNC) state are used by Vibrio species to survive and cope with diverse stress conditions including seasonal temperature downshifts and starvation. To learn more about the nature and specific contribution of membrane proteins to cell adaptation and survival, we analyzed variations in the protein composition of cell envelope and related them to morphological and physiological changes that were taking place during the long-term permanence of Vibrio harveyi in seawater microcosm at 4 °C. We found that after 21 days of permanence, nearly all population (ca. 99 %) of V. harveyi acquired the VBNC phenotype. Although the size of V. harveyi cells gradually decreased during the incubation time, we found that this morphological change was not directly related to their entry into the VBNC state. Our proteomic study revealed that the level of membrane proteins playing key roles in cellular transport, maintenance of cell structure, and in bioenergetics processes remained unchanged along starvation at low temperature, thus suggesting that V. harveyi might need these proteins for the long-term survival and/or for the resuscitation process. On a contrary, the level of two proteins, elongation factor Tu (EF-TU) and bacterioferritin, greatly increased reaching the maximal values by the end of the incubation period. We further discuss the above data with respect to the putative roles likely exerted by membrane proteins during transition to and maintaining of the VBNC state.

Survival of <i>Escherichia coli</i> under Nutrient-Deprived Conditions: Effect on Cell Envelope Subproteome

“…Despite the use of membrane fraction for mass spectrometry analysis, the PSORTb 3.0 program revealed that the resulting dataset potentially contained predicted cytosolic proteins (22%), including cytosolic subunits of ATP synthase or proteins that can conditionally be associated with the membrane (Tables 1 and 2). The fortuitous presence of cytoplasmic proteins in the membrane fractions was somewhat anticipated, as it was also observed in previous studies [24,31]. b NC, no significant changes with respect to the previous sample; ND, not detected.…”

“…Moreover, these authors reported a reduction in cellular size associated with the increase in the expression of the mreB gene. However, Ben Abdallah et al [65] and Parada et al [24] described the decline in the expression of the mreB gene and MreB protein content, respectively, in Vibrio species undergoing morphological changes in response to stress. Kruse et al [66] demonstrated that a decrease of MreB concentration leads to merodiploid spherical and inflated E. coli cells prone to cell lysis.…”

“…Membrane protein preparations were obtained according to the method described by Molloy et al [23] with minor variations [24]. Subsequent analysis of these proteins was performed by the Proteomics Core Facility-SGIKER at the University of the Basque Country, using the protocol previously described by Gonzalez-Fernandez et al [25].…”

“…Mass spectra were acquired using a data-independent acquisition mode (MSE) [26] as previously described by Gonzalez-Fernandez et al [25] and processed with ProteinLynx Global SERVER v2.4 Build RC7 (Waters Corporation). Protein identification was carried out using the database search algorithm of the program [27] and the parameters specified by Parada et al [24]. The absolute protein quantification based on peak area intensity of peptide precursors was calculated by the program using enolase peptides as an internal standard [28].…”

Analysis of Vibrio harveyi adaptation in sea water microcosms at elevated temperature provides insights into the putative mechanisms of its persistence and spread in the time of global warming

“…Analysis of V . harveyi adaptation revealed that deprivation of nutrients (starvation) can trigger profound morphological changes leading to reduction of cell size and conversion of rod-shaped bacteria into their coccoid-like variants 30–32 . In addition, when environmental conditions become unfavorable (e.g.…”