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PLoS Genet. 2018 Oct 8;14(10):e1007709. doi: 10.1371/journal.pgen.1007709. eCollection 2018 Oct.

LytTR Regulatory Systems: A potential new class of prokaryotic sensory system.

Author information

1
Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, Oregon, United States of America.
2
Department of Biology, Portland State University, Portland, Oregon, United States of America.
3
MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.
4
Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, Oregon, United States of America.

Abstract

The most commonly studied prokaryotic sensory signal transduction systems include the one-component systems, phosphosignaling systems, extracytoplasmic function (ECF) sigma factor systems, and the various types of second messenger systems. Recently, we described the regulatory role of two separate sensory systems in Streptococcus mutans that jointly control bacteriocin gene expression, natural competence development, as well as a cell death pathway, yet they do not function via any of the currently recognized signal transduction paradigms. These systems, which we refer to as LytTR Regulatory Systems (LRS), minimally consist of two proteins, a transcription regulator from the LytTR Family and a transmembrane protein inhibitor of this transcription regulator. Here, we provide evidence suggesting that LRS are a unique uncharacterized class of prokaryotic sensory system. LRS exist in a basal inactive state. However, when LRS membrane inhibitor proteins are inactivated, an autoregulatory positive feedback loop is triggered due to LRS regulator protein interactions with direct repeat sequences located just upstream of the -35 sequences of LRS operon promoters. Uncharacterized LRS operons are widely encoded by a vast array of Gram positive and Gram negative bacteria as well as some archaea. These operons also contain unique direct repeat sequences immediately upstream of their operon promoters indicating that positive feedback autoregulation is a globally conserved feature of LRS. Despite the surprisingly widespread occurrence of LRS operons, the only characterized examples are those of S. mutans. Therefore, the current study provides a useful roadmap to investigate LRS function in the numerous other LRS-encoding organisms.

PMID:
30296267
PMCID:
PMC6193735
DOI:
10.1371/journal.pgen.1007709
[Indexed for MEDLINE]
Free PMC Article

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