The Membrane Proteome of Spores and Vegetative Cells of the Food-Borne Pathogen Bacillus cereus

Abstract

Membrane proteins are fascinating since they play an important role in diverse cellular functions and constitute many drug targets. Membrane proteins are challenging to analyze. The spore, the most resistant form of known life, harbors a compressed inner membrane. This membrane acts not only as a barrier for undesired molecules but also as a scaffold for proteins involved in signal transduction and the transport of metabolites during spore germination and subsequent vegetative growth. In this study, we adapted a membrane enrichment method to study the membrane proteome of spores and cells of the food-borne pathogen Bacillus cereus using quantitative proteomics. Using bioinformatics filtering we identify and quantify 498 vegetative cell membrane proteins and 244 spore inner membrane proteins. Comparison of vegetative and spore membrane proteins showed there were 54 spore membrane-specific and 308 cell membrane-specific proteins. Functional characterization of these proteins showed that the cell membrane proteome has a far larger number of transporters, receptors and proteins related to cell division and motility. This was also reflected in the much higher expression level of many of these proteins in the cellular membrane for those proteins that were in common with the spore inner membrane. The spore inner membrane had specific expression of several germinant receptors and spore-specific proteins, but also seemed to show a preference towards the use of simple carbohydrates like glucose and fructose owing to only expressing transporters for these. These results show the differences in membrane proteome composition and show us the specific proteins necessary in the inner membrane of a dormant spore of this toxigenic spore-forming bacterium to survive adverse conditions.

Identification and characterization of new proteins crucial for bacterial spore resistance and germination

“…Consistent with the role of YetF and YdfS in spore heat resistance and their close relationship with 2Duf, yetF and ydfS genes exhibit the highest expression late in sporulation (see transcription browser in SubtiWiki; Pedreira et al, 2022 ) and their gene products have been identified in the IM fraction of spores of B. subtilis and homologs in Bacillus cereus spores’ IM ( Zheng et al, 2016 ; Gao et al, 2021 ). Since perturbation of spores’ IM has been shown to alter spore resistance not only to wet heat but also to agents that must cross the IM to damage spore core components, including DNA (formaldehyde and nitrous acid) or a core protein (H 2 O 2 ) ( Kanaan et al, 2021 ), the effects of yetF and ydfS mutations on spore resistance to these agents was also examined ( Figures 3A – C ).…”

“…There are many publications reporting mass spectrometry analyses of the proteome of B. subtilis , B. cereus and Clostridiodes difficile vegetative cells and spores, including IM proteins ( Zheng et al, 2016 ; Swarge et al, 2018 ; Abhyankar et al, 2019 ; Swarge et al, 2020 ; Gao et al, 2021 , 2022 ). Such work identified all five YetF homologs in the B. subtilis spore IM ( Zheng et al, 2016 ).…”

“…Presumably these spore proteins are degraded in spore outgrowth following germination. The B. cereus homolog with the best match to B. subtilis YetF (UniProt ID Q813Q8), as well as a 2Duf homolog (UniProt ID Q812J9), were also present in the B. cereus spore IM proteome (iBAQ ranks 559 and 626, respectively out of 1,254), but not in vegetative cells or the vegetative cell membrane fraction ( Gao et al, 2021 ). In addition, the one C. difficile spores’ 219 aa YetF homolog (UniProt ID Q187A0) was also identified in these spores’ IM proteome, with an approximate abundance at the median out of 1,021 proteins identified; this protein was also absent from the vegetative cell membrane fraction ( Abhyankar et al, 2019 ).…”

Tio2 Photocatalytic Biocidal Activity on Escherichia Coli and On Aspergillus Niger under Different Methodological Conditions

“…The ability of TiO2 to damage the cell membrane of E. coli explains its high antibacterial activity [22,41]. The differences between fungal cell membranes and bacterial ones may also contribute to the difference of TiO2 effects observed in our study [42,43].…”

HMMSTRTM: A hidden Markov model for local structure prediction in globular and membrane associated proteins

“…One region spans the membrane from the inside to the outside and the other which spans from outside to inside. This topology proved fruitful in predicting TMH regions of sequences determined to belong to TM proteins, and since its creation has been used to aid in experimental Protein Structure Determination (PSD) (Tani, et al 2021), and prediction of sequences belonging to TM proteins (Shinzato, et al 2021; Gao, et al 2021).…”