Exploring the lipoproteome of Parageobacillus thermoglucosidasius

Parageobacillus thermoglucosidasius is a thermophilic endospore-forming Bacillales of considerable biotechnological interest. Bacterial lipoproteins are a significant class of cell envelope components, influencing multiple aspects of the interactions of bacteria with their environments. We have therefore used a bioinformatic approach to identify the lipoproteins encoded in the P. thermoglucosidasius DSM 2542 type strain genome. Eighty-nine putative lipoproteins were found, representing ~2.3% of the P. thermoglucosidasius reference proteome; 84% (75) of these were also found in the predicted proteome of P. thermoglucosidasius strain Y4.1MC1. Just over half of the 89 putative lipoproteins are predicted to be substrate-binding proteins in ATP-binding cassette importer systems; others function in signalling pathways, protein translocation, redox processes, including the respiratory chain, and as enzymes. At least 10 lipoproteins are predicted to be involved in P. thermoglucosidasius spore cycle, whilst 15 are lipoproteins of unknown function. Proteomic analysis of P. thermoglucosidasius grown to exponential phase in Lysogeny Broth medium detected the expression of nearly 60% (52 out of 89) of the predicted lipoproteome, with the notable exception of those functionally linked to sporulation. These data contribute to the understanding of the P. thermoglucosidasius cell envelope and so should be of use to those studying the physiology, metabolism and biotechnological utility of this bacterium.