Small regulatory RNAs modulate lactococcal susceptibility to cell wall-targeting antimicrobials

Area of Science:

• Microbiology
• Bacterial Genetics
• RNA Biology

Background:

• Lactic acid bacteria (LAB) like Lactococcus cremoris possess cell wall defense mechanisms vital for survival.
• The role of small regulatory RNAs (sRNAs) in modulating these defenses in L. cremoris is largely unknown.
• Understanding sRNA regulation is crucial for developing strategies against bacterial environmental insults.

Purpose of the Study:

• To characterize small regulatory RNA (sRNA) profiles in Lactococcus cremoris.
• To investigate the impact of cell wall-targeting antimicrobials on sRNA expression.
• To identify specific sRNAs involved in bacterial resistance and stress responses.

Main Methods:

• Genome-wide identification and profiling of 193 putative small regulatory RNAs (sRNAs).
• Analysis of sRNA expression changes upon treatment with lysozyme and penicillin G.
• Functional screening to assess the role of identified sRNAs in antimicrobial resistance and stress response.

Main Results:

• 20 and 25 sRNAs showed altered expression after lysozyme and penicillin G treatments, respectively.
• Four sRNAs (sLLM1042+, sLLM2-, sLLM1993+, sLLM461+) differentially modulated lysozyme resistance.
• sLLM2- and sLLM1042+ influenced sensitivity to penicillin G, abiotic stresses, and tellurite, impacting gene regulation and protein levels.

Conclusions:

• Small regulatory RNAs (sRNAs) play a significant role in Lactococcus cremoris' response to cell wall-targeting antimicrobials.
• Specific sRNAs modulate bacterial resistance and sensitivity to various stresses, including antimicrobial agents.
• sRNA regulation may involve altering D-alanine levels, impacting cell wall synthesis and modification.