Mechanistic study of the immune defense function of the CRISPR1-Cas system in Enterococcus faecalis

Enterococci are Gram-positive cocci that are considered to be one of the causative agents of hospital-acquired infections. CRISPR-Cas is an adaptive immune system with targeted defense functions against foreign invading nucleic acids and plays an important role in antibiotic resistance. In this stud...

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Main Authors: Shuan Tao, Yewei Fang, Lin Zheng, He Zhang, Yao Xu, Wei Liang
Format: Article
Language:English
Published: Taylor & Francis Group 2025-12-01
Series:Virulence
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Online Access:https://www.tandfonline.com/doi/10.1080/21505594.2025.2530665
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author Shuan Tao
Yewei Fang
Lin Zheng
He Zhang
Yao Xu
Wei Liang
author_facet Shuan Tao
Yewei Fang
Lin Zheng
He Zhang
Yao Xu
Wei Liang
author_sort Shuan Tao
collection DOAJ
description Enterococci are Gram-positive cocci that are considered to be one of the causative agents of hospital-acquired infections. CRISPR-Cas is an adaptive immune system with targeted defense functions against foreign invading nucleic acids and plays an important role in antibiotic resistance. In this study, we aimed to investigate II-A CRISPR-Cas-mediated immunity and the molecular mechanism underlying the horizontal transfer of drug resistance genes in Enterococcus faecalis. The mutant strains were constructed by the homologous recombination strategy. The interference of plasmid transformation by the Enterococcus faecalis CRISPR1/Cas system was confirmed through plasmid transformation efficiency. The different mutation positions in the protospacer sequence S1 and PAM region recombinant plasmids were constructed through enzyme digestion and sequencing verification to assess the impact of the CRISPR-encoded immunity. In the wild-type strain, the transformation efficiency of plasmids pAT28-S1-S9 containing protospacers and PAM sites decreased (p < 0.05). Single-base mutations at positions 25 and 28 of the protospacer region eliminated the ability of the wild-type strain to prevent plasmid transformation containing the protospacer and PAM sites (p > 0.05), whereas a single mismatch at protospacer positions 2,10,18,23 did not affect the ability of CRISPR-Cas system-positive strains to interfere with plasmid transformation (p < 0.05). There was no significant difference between the wild-type strain and the mutant strain in the transformation efficiency of the pS1-pΔPAM plasmid without PAM and plasmids containing single mutations (p > 0.05). In conclusion, the CRISPR-Cas system can block the transformation of matching protospacer sequences, and mutations near or within the protospacer adjacent motif (PAM) allow the plasmid to escape CRISPR-encoded immunity.
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series Virulence
spelling doaj-art-90a8308d152d46b0ad7a0dd078e260732025-08-20T03:25:23ZengTaylor & Francis GroupVirulence2150-55942150-56082025-12-0116110.1080/21505594.2025.2530665Mechanistic study of the immune defense function of the CRISPR1-Cas system in Enterococcus faecalisShuan Tao0Yewei Fang1Lin Zheng2He Zhang3Yao Xu4Wei Liang5Department of Clinical Laboratory, The First Affiliated Hospital of Ningbo University, Ningbo, ChinaDepartment of Clinical Laboratory, The First Affiliated Hospital of Ningbo University, Ningbo, ChinaDepartment of Clinical Laboratory, The First Affiliated Hospital of Ningbo University, Ningbo, ChinaDepartment of Medical Laboratory, Bengbu Medical College, Bengbu, ChinaSchool of Medicine, Ningbo University, Ningbo, ChinaDepartment of Clinical Laboratory, The First Affiliated Hospital of Ningbo University, Ningbo, ChinaEnterococci are Gram-positive cocci that are considered to be one of the causative agents of hospital-acquired infections. CRISPR-Cas is an adaptive immune system with targeted defense functions against foreign invading nucleic acids and plays an important role in antibiotic resistance. In this study, we aimed to investigate II-A CRISPR-Cas-mediated immunity and the molecular mechanism underlying the horizontal transfer of drug resistance genes in Enterococcus faecalis. The mutant strains were constructed by the homologous recombination strategy. The interference of plasmid transformation by the Enterococcus faecalis CRISPR1/Cas system was confirmed through plasmid transformation efficiency. The different mutation positions in the protospacer sequence S1 and PAM region recombinant plasmids were constructed through enzyme digestion and sequencing verification to assess the impact of the CRISPR-encoded immunity. In the wild-type strain, the transformation efficiency of plasmids pAT28-S1-S9 containing protospacers and PAM sites decreased (p < 0.05). Single-base mutations at positions 25 and 28 of the protospacer region eliminated the ability of the wild-type strain to prevent plasmid transformation containing the protospacer and PAM sites (p > 0.05), whereas a single mismatch at protospacer positions 2,10,18,23 did not affect the ability of CRISPR-Cas system-positive strains to interfere with plasmid transformation (p < 0.05). There was no significant difference between the wild-type strain and the mutant strain in the transformation efficiency of the pS1-pΔPAM plasmid without PAM and plasmids containing single mutations (p > 0.05). In conclusion, the CRISPR-Cas system can block the transformation of matching protospacer sequences, and mutations near or within the protospacer adjacent motif (PAM) allow the plasmid to escape CRISPR-encoded immunity.https://www.tandfonline.com/doi/10.1080/21505594.2025.2530665Enterococcus faecalisantibiotic resistanceCRISPR-Casimmune defense mechanism
spellingShingle Shuan Tao
Yewei Fang
Lin Zheng
He Zhang
Yao Xu
Wei Liang
Mechanistic study of the immune defense function of the CRISPR1-Cas system in Enterococcus faecalis
Virulence
Enterococcus faecalis
antibiotic resistance
CRISPR-Cas
immune defense mechanism
title Mechanistic study of the immune defense function of the CRISPR1-Cas system in Enterococcus faecalis
title_full Mechanistic study of the immune defense function of the CRISPR1-Cas system in Enterococcus faecalis
title_fullStr Mechanistic study of the immune defense function of the CRISPR1-Cas system in Enterococcus faecalis
title_full_unstemmed Mechanistic study of the immune defense function of the CRISPR1-Cas system in Enterococcus faecalis
title_short Mechanistic study of the immune defense function of the CRISPR1-Cas system in Enterococcus faecalis
title_sort mechanistic study of the immune defense function of the crispr1 cas system in enterococcus faecalis
topic Enterococcus faecalis
antibiotic resistance
CRISPR-Cas
immune defense mechanism
url https://www.tandfonline.com/doi/10.1080/21505594.2025.2530665
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