Project description:Chemical communication is crucial in ecosystems with complex microbial assemblages. However, due to archaeal cultivation challenges, our understanding of the structure diversity and function of secondary metabolites (SMs) within archaeal communities is limited compared to the extensively studied and well-documented bacterial counterparts. Our comprehensive investigation into the biosynthetic potential of archaea, combined with metabolic analyses and the first report of heterologous expression in archaea, has unveiled the previously unexplored biosynthetic capabilities and chemical diversity of archaeal ribosomally synthesized and post-translationally modified peptide (RiPP). We have identified twenty-four new lanthipeptides of RiPPs exhibiting unique chemical characteristics, including a novel subfamily featuring an unexplored type with diamino-dicarboxylic (DADC) termini, largely expanding the chemical landscape of archaeal SMs. This sheds light on the chemical novelty of archaeal metabolites and emphasizes their potential as an untapped resource for natural product discovery. Additionally, archaeal lanthipeptides demonstrate specific antagonistic activity against haloarchaea, mediating the unique biotic interaction in the halophilic niche. Furthermore, they showcased a unique ecological role in enhancing the host's motility by inducing the rod-shaped cell morphology and upregulating the archaellum gene flgA1, facilitating the archaeal interaction with abiotic environments. These discoveries broaden our understanding of archaeal chemical language and provide promising prospects for future exploration of SM-mediated interaction.
Project description:Early and mature biofilm formation in the extremely halophilic euryarchaeon Halobacterium salinarum strain R1 was characterized by SWATH-LC/MS/MS. Using a simple surfactant-assisted protein solubilization protocol and one-dimensional ultrahigh performance nanoflow chromatography on the front end, 63.2% and 58.6% of the predicted Hbt. salinarum R1 proteome could be detected and quantified, respectively. Analysis of biophysical protein properties, functional analysis and pathway mapping indicate that we achieved a comprehensive characterization of the proteome. 60.8% of quantified proteins (or 34.5% of the predicted proteome) exhibited significant abundance changes between planktonic and biofilm states, demonstrating that haloarchaeal biofilm formation represents a profound “lifestyle change” on the molecular level. Taken together our results and analysis constitute the first comprehensive study to track the molecular changes from planktonic cells to initial and mature archaeal biofilms on the proteome level. Proteins exemplifying different protein expression level profiles were selected, and their corresponding gene transcripts targeted by qRT-PCR to test the feasibility of establishing rapid PCR-based assays for archaeal biofilm formation.
Project description:Diverse studies including protemoics, genome-wide binding, and transcriptional profiling of the model halophile Halobacterium salinarum suggest that its putative histone protein acts not as a chromatin protein but a direct and indirect transcriptional regulator. Here, we characterise the putative histone (HstA) of another model halophile (Haloferax volcanii) with ChIP-Seq to understand its genome-wide binding, and compare it with binding patterns seen from histones, nucleoid-associated proteins, and transcription factors of Halobacterium salinarum, other archaea, and eukaryotes. Analysis of this data by visual inspection, start site occupancy profiles, DNA motif searching, and dinucleotide periodicity suggests that the binding mode of halophilic histones shares features with TFs, NAPs, and more typical archaeal/eukaryotic histones.
