| Title | Essential role of proline synthesis and the one-carbon metabolism pathways for systemic virulence of Streptococcus pneumoniae |
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| Type | Journal article |
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| Authors | Ramos-Sevillano, Elisa, Ercoli, Giuseppe, Betts, Modupeh, Guerra-Assunção, José Afonso, Iverson, Amy, Frank, Matthew, Partridge, Frederick, Lo, Stephanie W., Fernandes, Vitor E., Nasher, Fauzy, Wall, Emma, Wren, Brendan, Gordon, Stephen B., Ferreira, Daniela M., Heyderman, Rob, Rosch, Jason and Brown, Jeremy S. |
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| Abstract | Virulence screens have indicated potential roles during Streptococcus pneumoniae infection for the one-carbon metabolism pathway component Fhs and proline synthesis mediated by ProABC. To define how these metabolic pathways affect S. pneumoniae virulence, we have investigated the phenotypes, transcription, and metabolic profiles of Δ fhs and Δ proABC mutants. S. pneumoniae capsular serotype 6B BHN418 Δ fhs and Δ proABC mutant strains had strongly reduced virulence in mouse sepsis and pneumonia models but could colonize the nasopharynx. Both mutant strains grew normally in complete media but had markedly impaired growth in chemically defined medium, human serum, and human cerebrospinal fluid. The BHN418 Δ proABC strain also had impaired growth under conditions of osmotic and oxidative stress. The virulence role of proABC was strain specific, as the D39 Δ proABC strain could still cause septicemia and grow in serum. Compared to culture in broth, in serum, the BHN418 Δ fhs and Δ proABC strains showed considerable derangement in global gene transcription that affected multiple but different metabolic pathways for each mutant strain. Metabolic data suggested that Δ fhs had an impaired stringent response, and when cultured in sera, BHN418 Δ fhs and Δ proABC were under increased oxidative stress and had altered lipid profiles. Loss of proABC also affected carbohydrate metabolism and the accumulation of peptidoglycan synthesis precursors in the BHN418 but not the D39 background, linking this phenotype to the conditional virulence phenotype. These data identify the S. pneumoniae metabolic functions affected by S. pneumoniae one-carbon metabolism and proline biosynthesis, and the role of these genetic loci for establishing systemic infection. IMPORTANCE Rapid adaptation to grow within the physiological conditions found in the host environment is an essential but poorly understood virulence requirement for systemic pathogens such as Streptococcus pneumoniae . We have now demonstrated an essential role for the one-carbon metabolism pathway and a conditional role depending on strain background for proline biosynthesis for S. pneumoniae growth in serum or cerebrospinal fluid, and therefore for systemic virulence. RNAseq and metabolomic data demonstrated that the loss of one-carbon metabolism or proline biosynthesis has profound but differing effects on S. pneumoniae metabolism in human serum, identifying the metabolic processes dependent on each pathway during systemic infection. These data provide a more detailed understanding of the adaptations required by systemic bacterial pathogens in order to cause infection and demonstrate that the requirement for some of these adaptations varies between strains from the same species and could therefore underpin strain variations in virulence potential. |
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| Journal | mBio |
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| Journal citation | 15 (11), pp. e01758-24 |
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| ISSN | 2150-7511 |
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| Year | 2024 |
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| Publisher | American Society for Microbiology |
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| Publisher's version | License CC BY 4.0 File Access Level Open (open metadata and files) |
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| Digital Object Identifier (DOI) | https://doi.org/10.1128/mbio.01758-24 |
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| PubMed ID | 39422467 |
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| Publication dates |
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| Published online | 18 Oct 2024 |
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| Published in print | Nov 2024 |
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| Project | R/N02687X/1 |
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| MR/R015651/1 |
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| Funder | UKRI | Medical Research Council |
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| UKRI | Medical Research Council |
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| NIHR | University College London Hospitals Biomedical Research Centre |
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