Proteomic Adaptation of Clostridioides difficile to Treatment with the Antimicrobial Peptide Nisin

Sandra Maaß,Rabea Schlüter,Jürgen Bartel,Pierre-Alexander Mücke,Dörte Becher,Thomas Sura,Sander H J Smits,Julia Zaschke-Kriesche

doi:10.3390/cells10020372

Sandra Maaß, Rabea Schlüter + Show 6 more

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https://doi.org/10.3390/cells10020372

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Abstract

Clostridioides difficile is the leading cause of antibiotic-associated diarrhea but can also result in more serious, life-threatening conditions. The incidence of C. difficile infections in hospitals is increasing, both in frequency and severity, and antibiotic-resistant C. difficile strains are advancing. Against this background antimicrobial peptides (AMPs) are an interesting alternative to classic antibiotics. Information on the effects of AMPs on C. difficile will not only enhance the knowledge for possible biomedical application but may also provide insights into mechanisms of C. difficile to adapt or counteract AMPs. This study applies state-of-the-art mass spectrometry methods to quantitatively investigate the proteomic response of C. difficile 630∆erm to sublethal concentrations of the AMP nisin allowing to follow the cellular stress adaptation in a time-resolved manner. The results do not only point at a heavy reorganization of the cellular envelope but also resulted in pronounced changes in central cellular processes such as carbohydrate metabolism. Further, the number of flagella per cell was increased during the adaptation process. The potential involvement of flagella in nisin adaptation was supported by a more resistant phenotype exhibited by a non-motile but hyper-flagellated mutant.

Highlights

Lantibiotics are ribosomally synthesized antimicrobial peptides produced by a range of Gram-positive bacteria [1]
In order to find a nisin concentration that exhibits sublethal effects to C. difficile cells and allows for sampling of intact cells, exponentially growing C. difficile 630∆erm in brain heart infusion (BHI) medium was treated with different amounts of nisin and the optical density was monitored for at least four hours after nisin addition (Figure 1)
While recent work describes an increase in dltD transcription during growth in the presence of nisin for 18 h [25], the metabolic proteins encoded by the dlt operon did not significantly accumulate within the 3 h after nisin addition examined in the current study

Summary

Introduction

Lantibiotics are ribosomally synthesized antimicrobial peptides produced by a range of Gram-positive bacteria [1]. During the synthesis of lantibiotics, posttranslational modifications lead to the creation of unusual amino acids such as dehydroalanine, dehydrobutyrine or lanthionine. The resulting lanthionine residues were eponymous (from lanthionine containing antibiotics) for this important class of bacteriocins and ensure the high antimicrobial activity of lantibiotics against various, mainly Gram-positive, bacteria. This high activity in combination with the high stability against proteolytic digestion facilitated the usage of lantibiotics as food preservatives. The cationic, linear peptide of 34 amino acids is naturally produced by Lactococcus lactis subsp. It has been shown that nisin exhibits antimicrobial effects on a range of nonfood-related bacteria such as Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant enterococci (VRE), and Streptococcus pneumoniae [7,8,9]

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