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Tn Smu1 is a functional integrative and conjugative element in Streptococcus mutans that when expressed causes growth arrest of host bacteria
Author(s) -
McLellan Lisa K.,
Anderson Mary E.,
Grossman Alan D.
Publication year - 2022
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14992
Subject(s) - biology , extrachromosomal dna , bacteria , gene , streptococcus mutans , horizontal gene transfer , microbiology and biotechnology , dna , repressor , phenotype , function (biology) , genetics , gene expression , plasmid , phylogenetics
Integrative and conjugative elements (ICEs) are major drivers of horizontal gene transfer in bacteria. They mediate their own transfer from host cells (donors) to recipients and allow bacteria to acquire new phenotypes, including pathogenic and metabolic capabilities and drug resistances. Streptococcus mutans , a major causative agent of dental caries, contains a putative ICE, Tn Smu1 , integrated at the 3′ end of a leucyl tRNA gene. We found that Tn Smu1 is a functional ICE, containing all the genes necessary for ICE function. It excised from the chromosome and excision was stimulated by DNA damage. We identified the DNA junctions generated by excision of Tn Smu1 , defined the ends of the element, and detected the extrachromosomal circle. We found that Tn Smu1 can transfer from S. mutans donors to recipients when co‐cultured on solid medium. The presence of Tn Smu1 in recipients inhibited successful acquisition of another copy and this inhibition was mediated, at least in part, by the likely transcriptional repressor encoded by the element. Using microscopy to track individual cells, we found that activation of Tn Smu1 caused an arrest of cell growth. Our results demonstrate that Tn Smu1 is a functional ICE that affects the biology of its host cells.