The world of asRNAs in Gram-negative and Gram-positive bacteria

Abstract

Bacteria exhibit an amazing diversity of mechanisms controlling gene expression to both maintain essential functions and modulate accessory functions in response to environmental cues. Over the years, it has become clear that bacterial regulation of gene expression is still far from fully understood. This review focuses on antisense RNAs (asRNAs), a class of RNA regulators defined by their location in cis and their perfect complementarity with their targets, as opposed to small RNAs (sRNAs) which act in trans with only short regions of complementarity. For a long time, only few functional asRNAs in bacteria were known and were almost exclusively found on mobile genetic elements (MGEs), thus, their importance among the other regulators was underestimated. However, the extensive application of global "omics" approaches has revealed the ubiquity of asRNAs in bacteria. This review aims, first, to describe the inherent ambiguity in the existence of asRNAs in bacteria, second, to highlight their diversity and their involvement in all aspects of bacterial life by presenting a list of 67 characterized asRNAs from both Grampositive and Gram-negative bacteria.

A Novel Regulation of K-antigen Capsule Synthesis in Porphyromonas gingivalis Is Driven by the Response Regulator PG0720-Directed Antisense RNA

“…Transcriptomic studies have shown that bacteria synthesize an array of antisense regulatory RNAs [ 53 ]. These molecules vary greatly in their size, their location in respect to sense strand genes, and the mechanisms by which they impact gene expression levels [ 53 ].…”

“…Transcriptomic studies have shown that bacteria synthesize an array of antisense regulatory RNAs [ 53 ]. These molecules vary greatly in their size, their location in respect to sense strand genes, and the mechanisms by which they impact gene expression levels [ 53 ]. A variety of bacterial antisense RNAs have been characterized and shown to play a role in regulating motility, iron acquisition, and biofilm development [ 54 ].…”

Diversity and Versatility in Small RNA-Mediated Regulation in Bacterial Pathogens

“…In bacterial pathogens, several examples of asRNAs overlapping an RBS have been described, and they go beyond plasmid replication-related functions ( Thomason and Storz, 2010 ; Lejars and Hajnsdorf, 2020 ). This is the case in Pseudomonas , Salmonella , Shigella , Clostridioides difficile , L. monocytogenes , and S. aureus , although precise demonstrations of this mechanism of action are lacking, and it is often linked to transcript abundance variations, as recently reviewed ( Lejars and Hajnsdorf, 2020 ). This indicates that translation inhibition and mRNA decay are often concomitant, as we will see for RNAIII in the next section.…”

Isatis indigotica: from (ethno) botany, biochemistry to synthetic biology

“…The leaf extracts can inhibit infection and proliferation of influenza A, H7N9, encephalitis B, mumps viruses, HSV-II, Dengue virus II, and Cytomegalovirus, among others (Ma, 2014 ; Zhou et al, 2006 ); directly neutralize and degrade endotoxin in actinomycin D-sensitized mice (Shi and Zhang, 2006 ) and promote interleukin 2 (IL-2) secretion by spleen lymphocytes induced by concanavalin A to enhance immunity in normal mice (Hsuan et al, 2009 ; Liang et al, 2000 ). They also have anti-bacterial effects against Staphylococcus aureus and Escherichia coli (Lejars and Hajnsdorf, 1863 ) and promote bile excretion and relieve pain (Hong et al, 2010 ; Liu et al, 2009 ). The root extracts have similar activities, such as inhibiting the human H7N9 avian influenza virus by preventing the virus from invading the host cells; inhibiting HSV-1 by preventing its replication and proliferation in cells; inhibiting E. coli , Staphylococcus epidermidis , Pneumococcus , Haemophilus influenzae , and Streptococcus ; and decreasing the levels of tumor necrosis factor-α (TNF-α) and IL-6 in peritoneal macrophages of mice (Hu et al, 2003 ; Wang et al, 2012 ).…”