Towards the Understanding of the Function of Lanthipeptide and TOMM-Related Genes in Haloferax mediterranei .

Research on secondary metabolites produced by Archaea such as ribosomally synthesized and post-translationally modified peptides (RiPPs) is limited. The genome of Haloferax mediterranei ATCC 33500 encodes lanthipeptide synthetases ( med M1, med M2, and med M3) and a thiazole-forming cyclodehydratase ( ycaO ), possibly involved in the biosynthesis of lanthipeptides and the TOMMs haloazolisins, respectively. Lanthipeptides and TOMMs often have antimicrobial activity, and H. mediterranei has antagonistic activity towards haloarchaea shown to be independent of med M genes. This study investigated (i) the transcription of ycaO and med M genes, (ii) the involvement of YcaO in bioactivity, and (iii) the impact of YcaO and MedM-encoding genes' absence in the biomolecular profile of H. mediterranei . The assays were performed with biomass grown in agar and included RT-qPCR, the generation of knockout mutants, bioassays, and FTIR analysis. Results suggest that ycaO and med M genes are transcriptionally active, with the highest number of transcripts observed for med M2. The deletion of ycaO gene had no effect on H. mediterranei antihaloarchaea activity. FTIR analysis of med M and ycaO knockout mutants suggest that MedMs and YcaO activity might be directly or indirectly related t lipids, a novel perspective that deserves further investigation.