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Guérin H, Courtin P, Guillot A, Péchoux C, Mahony J, van Sinderen D, Kulakauskas S, Cambillau C, Touzé T, Chapot-Chartier MP. Molecular mechanisms underlying the structural diversity of rhamnose-rich cell wall polysaccharides in lactococci. J Biol Chem 2024; 300:105578. [PMID: 38110036 PMCID: PMC10821137 DOI: 10.1016/j.jbc.2023.105578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 12/04/2023] [Accepted: 12/11/2023] [Indexed: 12/20/2023] Open
Abstract
In Gram-positive bacteria, cell wall polysaccharides (CWPS) play critical roles in bacterial cell wall homeostasis and bacterial interactions with their immediate surroundings. In lactococci, CWPS consist of two components: a conserved rhamnan embedded in the peptidoglycan layer and a surface-exposed polysaccharide pellicle (PSP), which are linked together to form a large rhamnose-rich CWPS (Rha-CWPS). PSP, whose structure varies from strain to strain, is a receptor for many bacteriophages infecting lactococci. Here, we examined the first two steps of PSP biosynthesis, using in vitro enzymatic tests with lipid acceptor substrates combined with LC-MS analysis, AlfaFold2 modeling of protein 3D-structure, complementation experiments, and phage assays. We show that the PSP repeat unit is assembled on an undecaprenyl-monophosphate (C55P) lipid intermediate. Synthesis is initiated by the WpsA/WpsB complex with GlcNAc-P-C55 synthase activity and the PSP precursor GlcNAc-P-C55 is then elongated by specific glycosyltransferases that vary among lactococcal strains, resulting in PSPs with diverse structures. Also, we engineered the PSP biosynthesis pathway in lactococci to obtain a chimeric PSP structure, confirming the predicted glycosyltransferase specificities. This enabled us to highlight the importance of a single sugar residue of the PSP repeat unit in phage recognition. In conclusion, our results support a novel pathway for PSP biosynthesis on a lipid-monophosphate intermediate as an extracellular modification of rhamnan, unveiling an assembly machinery for complex Rha-CWPS with structural diversity in lactococci.
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Affiliation(s)
- Hugo Guérin
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Pascal Courtin
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Alain Guillot
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Christine Péchoux
- Université Paris-Saclay INRAE, AgroParisTech, GABI, Jouy-en-Josas, France
| | - Jennifer Mahony
- School of Microbiology and APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Douwe van Sinderen
- School of Microbiology and APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Saulius Kulakauskas
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Christian Cambillau
- School of Microbiology and APC Microbiome Ireland, University College Cork, Cork, Ireland; Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie, Bioénergies et Biotechnologie (IMM), Aix-Marseille Université - CNRS, UMR 7255, Marseille, France
| | - Thierry Touzé
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
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Seiler J, Millen A, Romero DA, Magill D, Simdon L. Novel P335-like Phage Resistance Arises from Deletion within Putative Autolysin yccB in Lactococcus lactis. Viruses 2023; 15:2193. [PMID: 38005870 PMCID: PMC10675428 DOI: 10.3390/v15112193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 10/18/2023] [Accepted: 10/26/2023] [Indexed: 11/26/2023] Open
Abstract
Lactococcus lactis and Lactococcus cremoris are broadly utilized as starter cultures for fermented dairy products and are inherently impacted by bacteriophage (phage) attacks in the industrial environment. Consequently, the generation of bacteriophage-insensitive mutants (BIMs) is a standard approach for addressing phage susceptibility in dairy starter strains. In this study, we characterized spontaneous BIMs of L. lactis DGCC12699 that gained resistance against homologous P335-like phages. Phage resistance was found to result from mutations in the YjdB domain of yccB, a putative autolysin gene. We further observed that alteration of a fused tail-associated lysin-receptor binding protein (Tal-RBP) in the phage restored infectivity on the yccB BIMs. Additional investigation found yccB homologs to be widespread in L. lactis and L. cremoris and that different yccB homologs are highly correlated with cell wall polysaccharide (CWPS) type/subtype. CWPS are known lactococcal phage receptors, and we found that truncation of a glycosyltransferase in the cwps operon also resulted in resistance to these P335-like phages. However, characterization of the CWPS mutant identified notable differences from the yccB mutants, suggesting the two resistance mechanisms are distinct. As phage resistance correlated with yccB mutation has not been previously described in L. lactis, this study offers insight into a novel gene involved in lactococcal phage sensitivity.
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Affiliation(s)
- Jenny Seiler
- IFF, Madison, WI 53716, USA; (A.M.); (D.A.R.); (L.S.)
| | - Anne Millen
- IFF, Madison, WI 53716, USA; (A.M.); (D.A.R.); (L.S.)
| | | | | | - Laura Simdon
- IFF, Madison, WI 53716, USA; (A.M.); (D.A.R.); (L.S.)
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