The secretory (Sec) pathway is the major pathway of Bacillus subtilis for protein export from the cytoplasm to the extracellular milieu. An amino‐terminal signal peptide is required to initiate protein translocation across the cytoplasmic membrane via Sec. Generally, Sec pathway signal peptides of B. subtilis are around 20–30 amino acids long and tend to be relatively hydrophobic compared to signal peptides from other organisms. In view of the importance of signal peptides for high‐level secretory protein production, understanding how signal peptide structure and length influence the efficiency of protein secretion is crucial. Accordingly, the present study was aimed at investigating the effects of signal peptide size and, in particular the subdomain sizes of a signal peptide, in relation to protein secretion efficiency. To this end, a rational engineering approach was employed for the design of shortened signal peptides that can still drive effective protein secretion. This involved in silico interaction studies with the signal recognition particle, which is involved in protein targeting from the ribosome to the membrane. Our results show that the hydrophobic H‐domain of a B. subtilis signal peptide can be shortened from seventeen to seven hydrophobic amino acid residues without a detectable decrease in protein secretion.
D. A. Pranoto, Danilo Milo, Lorenzo de la Parra Soto et al.· Microbial Biotechnology· 0 citations
Faecalibacterium is one of the most abundant anaerobes in the human colon. At the genus level, this bacterium shows a strong positive association with human health. Expanding collections of isolates and metagenome-assembled genomes have revealed its species diversity, yet species-level functions remain so far underexplored. Here, we describe a novel species, Faecalibacterium harmsenii. In addition, we reclassify another isolate as a member of the recently reported F. langellae species. Despite close genomic relatedness, these isolates exhibit distinct physiological and biochemical traits, including differences in carbohydrate utilization, stress tolerance, enzymatic activity, Gram-staining and fatty acid composition. Our present comparative genomics analyses further uncover extensive functional diversity and plasticity across type strains, with F. harmsenii being distinguished by an expanded carbohydrate gene repertoire and reduced defense systems, mobile genetic elements and antibiotic resistance genes. Extending to the species, we identify species-specific ecological niches across hosts and differential sensitivities to human diseases, highlighting certain species as reliable biomarkers of gut health. Together, these findings refine our understanding of Faecalibacterium diversity and provide a framework for its use in microbiome-based diagnostics and therapeutic development.
Qiqi Pan, E. Tsompanidou, Wenbing Hu et al.· ISME Communications· 0 citations
