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Characterization of a Type II-A CRISPR-Cas System in Streptococcus mutans.
mSphere. 2020 Jun 24; 5(3)M

Abstract

Streptococcus mutans and its virulent phages are important members of the human oral microbiota. S. mutans is also the primary causal agent of dental caries. To survive in this ecological niche, S. mutans must encode phage defense mechanisms, which include CRISPR-Cas systems. Here, we describe the CRISPR-Cas type II-A system of S. mutans strain P42S, which was found to display natural adaptation and interference activity in response to phage infection and plasmid transformation. Newly acquired spacers were integrated both at the 5' end of the CRISPR locus and ectopically. In comparisons of the cas genes of P42S to those of other strains of S. mutans, cas1, cas2, and csn2 appear to be highly conserved within the species. However, more diversity was observed with cas9 While the nuclease domains of S. mutans Cas9 (SmCas9) are conserved, the C terminus of the protein, including the protospacer adjacent motif (PAM) recognition domain, is less conserved. In support of these findings, we experimentally demonstrated that the PAMs associated with SmCas9 of strain P42S are NAA and NGAA. These PAMs are different from those previously reported for the CRISPR-Cas system of the model strain S. mutans UA159. This study illustrates the diversity of CRISPR-Cas type II-A systems that can be found within the same bacterial species.IMPORTANCE CRISPR-Cas is one of the mechanisms used by bacteria to defend against viral predation. Increasing our knowledge of the biology and diversity of CRISPR-Cas systems will also improve our understanding of virus-bacterium interactions. As CRISPR-Cas systems acquiring novel immunities under laboratory conditions are rare, Streptococcus mutans strain P42S provides an alternative model to study the adaptation step, which is still the least understood step in CRISPR-Cas biology. Furthermore, the availability of a natural Cas9 protein recognizing an AT-rich PAM opens up new avenues for genome editing purposes.

Authors+Show Affiliations

Département de Biochimie, de Microbiologie, et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec City, Quebec, Canada. Groupe de Recherche en Écologie Buccale, Faculté de Médecine Dentaire, Université Laval, Québec City, Quebec, Canada.Département de Biochimie, de Microbiologie, et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec City, Quebec, Canada Sylvain.Moineau@bcm.ulaval.ca. Groupe de Recherche en Écologie Buccale, Faculté de Médecine Dentaire, Université Laval, Québec City, Quebec, Canada. Félix d'Hérelle Reference Center for Bacterial Viruses, Faculté de Médecine Dentaire, Université Laval, Québec City, Quebec, Canada.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

32581075

Citation

Mosterd, Cas, and Sylvain Moineau. "Characterization of a Type II-A CRISPR-Cas System in Streptococcus Mutans." MSphere, vol. 5, no. 3, 2020.
Mosterd C, Moineau S. Characterization of a Type II-A CRISPR-Cas System in Streptococcus mutans. mSphere. 2020;5(3).
Mosterd, C., & Moineau, S. (2020). Characterization of a Type II-A CRISPR-Cas System in Streptococcus mutans. MSphere, 5(3). https://doi.org/10.1128/mSphere.00235-20
Mosterd C, Moineau S. Characterization of a Type II-A CRISPR-Cas System in Streptococcus Mutans. mSphere. 2020 Jun 24;5(3) PubMed PMID: 32581075.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Characterization of a Type II-A CRISPR-Cas System in Streptococcus mutans. AU - Mosterd,Cas, AU - Moineau,Sylvain, Y1 - 2020/06/24/ PY - 2020/6/26/entrez PY - 2020/6/26/pubmed PY - 2020/6/26/medline KW - CRISPR KW - CRISPR-Cas KW - Cas9 KW - Streptococcus KW - bacteriophages KW - mutans KW - phage resistance KW - plasmids KW - spacers JF - mSphere JO - mSphere VL - 5 IS - 3 N2 - Streptococcus mutans and its virulent phages are important members of the human oral microbiota. S. mutans is also the primary causal agent of dental caries. To survive in this ecological niche, S. mutans must encode phage defense mechanisms, which include CRISPR-Cas systems. Here, we describe the CRISPR-Cas type II-A system of S. mutans strain P42S, which was found to display natural adaptation and interference activity in response to phage infection and plasmid transformation. Newly acquired spacers were integrated both at the 5' end of the CRISPR locus and ectopically. In comparisons of the cas genes of P42S to those of other strains of S. mutans, cas1, cas2, and csn2 appear to be highly conserved within the species. However, more diversity was observed with cas9 While the nuclease domains of S. mutans Cas9 (SmCas9) are conserved, the C terminus of the protein, including the protospacer adjacent motif (PAM) recognition domain, is less conserved. In support of these findings, we experimentally demonstrated that the PAMs associated with SmCas9 of strain P42S are NAA and NGAA. These PAMs are different from those previously reported for the CRISPR-Cas system of the model strain S. mutans UA159. This study illustrates the diversity of CRISPR-Cas type II-A systems that can be found within the same bacterial species.IMPORTANCE CRISPR-Cas is one of the mechanisms used by bacteria to defend against viral predation. Increasing our knowledge of the biology and diversity of CRISPR-Cas systems will also improve our understanding of virus-bacterium interactions. As CRISPR-Cas systems acquiring novel immunities under laboratory conditions are rare, Streptococcus mutans strain P42S provides an alternative model to study the adaptation step, which is still the least understood step in CRISPR-Cas biology. Furthermore, the availability of a natural Cas9 protein recognizing an AT-rich PAM opens up new avenues for genome editing purposes. SN - 2379-5042 UR - https://www.unboundmedicine.com/medline/citation/32581075/Characterization_of_a_Type_II-A_CRISPR-Cas_System_in_Streptococcus_mutans L2 - https://doi.org/10.1128/mSphere.00235-20 DB - PRIME DP - Unbound Medicine ER -
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