Project description:Ammonia-oxidizing archaea (AOA) play important roles in nitrogen and carbon cycling in marine and terrestrial ecosystems. Here, we present the draft genome sequence for the ammonia-oxidizing archaeon "Candidatus Nitrosopumilus salaria" BD31, which was enriched in culture from sediments of the San Francisco Bay estuary. The genome sequences revealed many similarities to the genome of Nitrosopumilus maritimus.
Project description:<p>Archaea are differentiated from the other two domains of life by their biomolecular characteristics. One such characteristic is the unique structure and composition of their lipids. Characterization of the whole set of lipids in a biological system (the lipidome) remains technologically challenging. This is because the lipidome is innately complex, and not all lipid species are extractable, separable or ionizable by a single analytical method. Furthermore, lipids are structurally and chemically diverse. Many lipids are isobaric or isomeric and often indistinguishable by the measurement of mass or even their fragmentation spectra. Here we developed a novel analytical protocol based on liquid chromatography ion mobility mass spectrometry to enhance the coverage of the lipidome and characterize the conformations of archaeal lipids by their collision cross-sections (CCSs). The measurements of ion mobility revealed the gas-phase ion chemistry of representative archaeal lipids and provided further insights into their attributions to the adaptability of archaea to environmental stresses. A comprehensive characterization of the lipidome of mesophilic marine thaumarchaeon, <em>Nitrosopumilus maritimus</em> (strain SCM1) revealed potentially an unreported phosphate- and sulfate-containing lipid candidate by negative ionization analysis. It was the first time that experimentally derived CCS values of archaeal lipids were reported. Discrimination of crenarchaeol and its proposed stereoisomer was, however, not achieved with the resolving power of the SYNAPT G2 ion mobility system, and a high-resolution ion mobility system may be required for future work. Structural and spectral libraries of archaeal lipids were constructed in non-vendor-specific formats and are being made available to the community to promote research of Archaea by lipidomics. </p>
Project description:Casposase, a homolog of Cas1 integrase, is encoded by a superfamily of mobile genetic elements known as casposons. While family 2 casposase has been well documented in both function and structure, little is known about the other three casposase families. Here, we studied the family 1 casposase lacking the helix-turn-helix (HTH) domain from Candidatus Nitrosopumilus koreensis AR1 (Ca. N. koreensis). The determinants for integration by Ca. N. koreensis casposase were extensively investigated, and it was found that a 13-bp target site duplication (TSD) sequence, a minimal 3-bp leader and three different nucleotides of the TSD sequences are indispensable for target specific integration. Significantly, the casposase can site-specifically integrate a broad range of terminal inverted repeat (TIR)-derived oligonucleotides ranging from 7-nt to ∼4000-bp, and various oligonucleotides lacking the 5'-TTCTA-3' motif at the 3' end of TIR sequence can be integrated efficiently. Furthermore, similar to some Cas1 homologs, the casposase utilizes a 5'-ATAA-3' motif in the TSD as a molecular ruler to dictate nucleophilic attack at 9-bp downstream of the end of the ruler during the spacer-side integration. By characterizing the family 1 Ca. N. koreensis casposase, we have extended our understanding on mechanistic similarities and evolutionary connections between casposons and the adaptation elements of CRISPR-Cas immunity.
Project description:Ammonia-oxidizing archaea (AOA) are ubiquitous in various marine environments and play important roles in the global nitrogen and carbon cycles. We here present a high-quality draft genome sequence of an ammonia-oxidizing archaeon, "Candidatus Nitrosopumilus koreensis" AR1, which was found to dominate an ammonia-oxidizing enrichment culture in marine sediment off Svalbard, the Arctic Circle. Despite a significant number of nonoverlapping genes (ca. 30%), similarities of this strain to "Candidatus Nitrosopumilus maritimus" were revealed by core genes for archaeal ammonia oxidation and carbon fixation, G+C content, and extensive synteny conservation.