8 research outputs found
The importance of biofilm formation for cultivation of a Micrarchaeon and its interactions with its Thermoplasmatales host
Micrarchaeota is a distinctive lineage assigned to the DPANN archaea, which includes poorly characterised microorganisms with reduced genomes that likely depend on interactions with hosts for growth and survival. Here, we report the enrichment of a stable co-culture of a member of the Micrarchaeota (Ca. Micrarchaeum harzensis) together with its Thermoplasmatales host (Ca. Scheffleriplasma hospitalis), as well as the isolation of the latter. We show that symbiont-host interactions depend on biofilm formation as evidenced by growth experiments, comparative transcriptomic analyses and electron microscopy. In addition, genomic, metabolomic, extracellular polymeric substances and lipid content analyses indicate that the Micrarchaeon symbiont relies on the acquisition of metabolites from its host. Our study of the cell biology and physiology of a Micrarchaeon and its host adds to our limited knowledge of archaeal symbioses
Biochemical Characterization of Recombinant Isocitrate Dehydrogenase and Its Putative Role in the Physiology of an Acidophilic Micrarchaeon
Despite several discoveries in recent years, the physiology of acidophilic Micrarchaeota, such as “Candidatus Micrarchaeum harzensis A_DKE”, remains largely enigmatic, as they highly express numerous genes encoding hypothetical proteins. Due to a lacking genetic system, it is difficult to elucidate the biological function of the corresponding proteins and heterologous expression is required. In order to prove the viability of this approach, A_DKE’s isocitrate dehydrogenase (MhIDH) was recombinantly produced in Escherichia coli and purified to electrophoretic homogeneity for biochemical characterization. MhIDH showed optimal activity around pH 8 and appeared to be specific for NADP+ yet promiscuous regarding divalent cations as cofactors. Kinetic studies showed KM-values of 53.03 ± 5.63 µM and 1.94 ± 0.12 mM and kcat-values of 38.48 ± 1.62 and 43.99 ± 1.46 s−1 resulting in kcat/KM-values of 725 ± 107.62 and 22.69 ± 2.15 mM−1 s−1 for DL-isocitrate and NADP+, respectively. MhIDH’s exceptionally low affinity for NADP+, potentially limiting its reaction rate, can likely be attributed to the presence of a proline residue in the NADP+ binding pocket, which might cause a decrease in hydrogen bonding of the cofactor and a distortion of local secondary structure
A Micrarchaeon Isolate Is Covered by a Proteinaceous S-Layer
Our knowledge about the DPANN superphylum, which comprises several archaeal phyla with limited metabolic capacities, is mostly based on genomic data derived from cultivation-independent approaches. This study examined the surface structure of a recently cultivated member “ Candidatus Micrarchaeum harzensis A_DKE,” an archaeal symbiont dependent on an interaction with a host organism for growth
A Micrarchaeon Isolate Is Covered by a Proteinaceous S-Layer
In previous publications, it was hypothesized that Micrarchaeota cells are covered by two individual membrane systems. This study proves that at least the recently cultivated "Candidatus Micrarchaeum harzensis A_DKE" possesses an S-layer covering its cytoplasmic membrane. The potential Slayer protein was found to be among the proteins with the highest abundance in "Ca. Micrarchaeum harzensis A_DKE," and in silico characterization of its primary structure indicated homologies to other known S-layer proteins. Homologues of this protein were found in other Micrarchaeota genomes, which raises the question of whether the ability to form an S-layer is a common trait within this phylum. The S-layer protein seems to be glycosylated, and the micrarchaeon expresses genes for N-glycosylation under cultivation conditions, despite not being able to synthesize carbohydrates. Electron micrographs of freeze-etched samples of a previously described coculture, containing "Ca. Micrarchaeum harzensis A_DKE" and a Thermopiasmatales member as its host organism, verified the hypothesis of an S-layer on the surface of "Ca. Micrarchaeum harzensis A_DKE." Both organisms are clearly distinguishable by cell size, shape, and surface structure. IMPORTANCE Our knowledge about the DPANN superphylum, which comprises several archaeal phyla with limited metabolic capacities, is mostly based on genomic data derived from cultivation-independent approaches. This study examined the surface structure of a recently cultivated member "Candidatus Micrarchaeum harzensis A_DKE," an archaeal symbiont dependent on an interaction with a host organism for growth. The interaction requires direct cell contact between interaction partners, a mechanism which is also described for other DPANN archaea. Investigating the surface structure of "Ca. Micrarchaeum harzensis A_DKE" is an important step toward understanding the interaction between Micrarchaeota and their host organisms and living with limited metabolic capabilities, a trait shared by several DPANN archaea
The importance of biofilm formation for cultivation of a Micrarchaeon and its interactions with its Thermoplasmatales host (metabolome data)
Micrarchaeota is a distinctive lineage assigned to the DPANN archaea, which includes poorly characterized microorganisms with reduced genomes that likely depend on interactions with hosts for growth and survival. Here, we report the enrichment of a stable co-culture of a member of the Micrarchaeota (Ca. Micrarchaeum harzensis) together with its Thermoplasmatales host (Ca. Scheffleriplasma hospitalis), as well as the isolation of the latter. We show that symbiont-host interactions depend on biofilm formation as evidenced by growth experiments, comparative transcriptomic analyses and electron microscopy. In addition, genomic, metabolomic, extracellular polymeric substances and lipid content analyses indicate that the Micrarchaeon symbiont relies on the acquisition of metabolites from its host. Our study of the cell biology and physiology of a Micrarchaeon and its host adds to our limited knowledge of archaeal symbioses
The importance of biofilm formation for cultivation of a Micrarchaeon and its interactions with its Thermoplasmatales host
Micrarchaeota is a distinctive lineage assigned to the DPANN archaea, which includes poorly characterised microorganisms with reduced genomes that likely depend on interactions with hosts for growth and survival. Here, we report the enrichment of a stable co-culture of a member of the Micrarchaeota (Ca. Micrarchaeum harzensis) together with its Thermoplasmatales host (Ca. Scheffleriplasma hospitalis), as well as the isolation of the latter. We show that symbiont-host interactions depend on biofilm formation as evidenced by growth experiments, comparative transcriptomic analyses and electron microscopy. In addition, genomic, metabolomic, extracellular polymeric substances and lipid content analyses indicate that the Micrarchaeon symbiont relies on the acquisition of metabolites from its host. Our study of the cell biology and physiology of a Micrarchaeon and its host adds to our limited knowledge of archaeal symbioses. The Micrarchaeota lineage includes poorly characterized archaea with reduced genomes that likely depend on host interactions for survival. Here, the authors report a stable co-culture of a member of the Micrarchaeota and its host, and use multi-omic and physiological analyses to shed light on this symbiosis
The importance of biofilm formation for cultivation of a Micrarchaeon and its interactions with its Thermoplasmatales host
Micrarchaeota is a distinctive lineage assigned to the DPANN archaea, which includes poorly characterised microorganisms with reduced genomes that likely depend on interactions with hosts for growth and survival. Here, we report the enrichment of a stable co-culture of a member of the Micrarchaeota (Ca. Micrarchaeum harzensis) together with its Thermoplasmatales host (Ca. Scheffleriplasma hospitalis), as well as the isolation of the latter. We show that symbiont-host interactions depend on biofilm formation as evidenced by growth experiments, comparative transcriptomic analyses and electron microscopy. In addition, genomic, metabolomic, extracellular polymeric substances and lipid content analyses indicate that the Micrarchaeon symbiont relies on the acquisition of metabolites from its host. Our study of the cell biology and physiology of a Micrarchaeon and its host adds to our limited knowledge of archaeal symbioses. The Micrarchaeota lineage includes poorly characterized archaea with reduced genomes that likely depend on host interactions for survival. Here, the authors report a stable co-culture of a member of the Micrarchaeota and its host, and use multi-omic and physiological analyses to shed light on this symbiosis