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1,050 results on '"Abee, Tjakko"'

30. Probing Peptidoglycan Synthesis in the Gut Commensal Akkermansia muciniphila with Bioorthogonal Chemical Reporters

Author

Sminia, Tjerk, Aalvink, Steven, de Jong, Hanna, Tempelaars, Marcel, Zuilhof, Han, Abee, Tjakko, de Vos, Willem, Tytgat, Hanne, Wennekes, Tom, Sminia, Tjerk, Aalvink, Steven, de Jong, Hanna, Tempelaars, Marcel, Zuilhof, Han, Abee, Tjakko, de Vos, Willem, Tytgat, Hanne, and Wennekes, Tom

Abstract

Our gut microbiota directly influences human physiology in health and disease. The myriad of surface glycoconjugates in both the bacterial cell envelope and our gut cells dominate the microbiota-host interface and play a critical role in host response and microbiota homeostasis. Among these, peptidoglycan is the basic glycan polymer offering the cell rigidity and a basis on which many other glycoconjugates are anchored. To directly study peptidoglycan in gut commensals and obtain the molecular insight required to understand their functional activities we need effective techniques like chemical probes to label peptidoglycan in live bacteria. Here we report a chemically guided approach to study peptidoglycan in a key mucin-degrading gut microbiota member of the Verrucomicrobia phylum, Akkermansia muciniphila. Two novel non-toxic tetrazine click-compatible peptidoglycan probes with either a cyclopropene or isonitrile handle allowed for the detection and imaging of peptidoglycan synthesis in this intestinal species.

Published
2024

31. Ribosomal mutations enable a switch between high fitness and high stress resistance in Listeria monocytogenes

Author

Koomen, Jeroen, Ma, Xuchuan, Bombelli, Alberto, Tempelaars, Marcel H., Boeren, Sjef, Zwietering, Marcel H., den Besten, Heidy M.W., Abee, Tjakko, Koomen, Jeroen, Ma, Xuchuan, Bombelli, Alberto, Tempelaars, Marcel H., Boeren, Sjef, Zwietering, Marcel H., den Besten, Heidy M.W., and Abee, Tjakko

Abstract

Multiple stress resistant variants of Listeria monocytogenes with mutations in rpsU encoding ribosomal protein RpsU have previously been isolated after a single exposure to acid stress. These variants, including L. monocytogenes LO28 variant V14 with a complete deletion of the rpsU gene, showed upregulation of the general stress sigma factor Sigma B-mediated stress resistance genes and had a lower maximum specific growth rate than the LO28 WT, signifying a trade-off between stress resistance and fitness. In the current work V14 has been subjected to an experimental evolution regime, selecting for higher fitness in two parallel evolving cultures. This resulted in two evolved variants with WT-like fitness: 14EV1 and 14EV2. Comparative analysis of growth performance, acid and heat stress resistance, in combination with proteomics and RNA-sequencing, indicated that in both lines reversion to WT-like fitness also resulted in WT-like stress sensitivity, due to lack of Sigma B-activated stress defense. Notably, genotyping of 14EV1 and 14EV2 provided evidence for unique point-mutations in the ribosomal rpsB gene causing amino acid substitutions at the same position in RpsB, resulting in RpsB22Arg-His and RpsB22Arg-Ser, respectively. Combined with data obtained with constructed RpsB22Arg-His and RpsB22Arg-Ser mutants in the V14 background, we provide evidence that loss of function of RpsU resulting in the multiple stress resistant and reduced fitness phenotype, can be reversed by single point mutations in rpsB leading to arginine substitutions in RpsB at position 22 into histidine or serine, resulting in a WT-like high fitness and low stress resistance phenotype. This demonstrates the impact of genetic changes in L. monocytogenes’ ribosomes on fitness and stress resistance.

Published
2024

49. A single point mutation in the Listeria monocytogenes ribosomal gene rpsU enables SigB activation independently of the stressosome and the anti-sigma factor antagonist RsbV.

Author

Xuchuan Ma, Tempelaars, Marcel H., Zwietering, Marcel H., Boeren, Sjef, O'Byrne, Conor P., den Besten, Heidy M. W., and Abee, Tjakko

Subjects
LISTERIA monocytogenes, SIGMA receptors, RIBOSOMAL proteins, PHENOTYPIC plasticity, MICROORGANISM populations, CELL populations
Abstract

Microbial population heterogeneity leads to different stress responses and growth behavior of individual cells in a population. Previously, a point mutation in the rpsU gene (rpsUG50C) encoding ribosomal protein S21 was identified in a Listeria monocytogenes LO28 variant, which leads to increased multistress resistance and a reduced maximum specific growth rate. However, the underlying mechanisms of these phenotypic changes remain unknown. In L. monocytogenes, the alternative sigma factor SigB regulates the general stress response, with its activation controlled by a series of Rsb proteins, including RsbR1 and anti-sigma factor RsbW and its antagonist RsbV. We combined a phenotype and proteomics approach to investigate the acid and heat stress resistance, growth rate, and SigB activation of L. monocytogenes EGDe wild type and the ΔsigB, ΔrsbV, and ΔrsbR1 mutant strains. While the introduction of rpsUG50C in the ΔsigB mutant did not induce a SigB-mediated increase in robustness, the presence of rpsUG50C in the ΔrsbV and the ΔrsbR1 mutants led to SigB activation and concomitant increased robustness, indicating an alternative signaling pathway for the SigB activation in rpsUG50C mutants. Interestingly, all these rpsUG50C mutants exhibited reduced maximum specific growth rates, independent of SigB activation, possibly attributed to compromised ribosomal functioning. In summary, the increased stress resistance in the L. monocytogenes EGDe rpsUG50C mutant results from SigB activation through an unknown mechanism distinct from the classical stressosome and RsbV/RsbW partner switching model. Moreover, the reduced maximum specific growth rate of the EGDe rpsUG50C mutant is likely unrelated to SigB activation and potentially linked to impaired ribosomal function. [ABSTRACT FROM AUTHOR]

Published
2024
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