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Sonja-verena Albers – One of the best experts on this subject based on the ideXlab platform.

  • taxis in Archaea
    Emerging Topics in Life Sciences, 2018
    Co-Authors: Tessa E F Quax, Sonja-verena Albers, Friedhelm Pfeiffer


    Microorganisms can move towards favorable growth conditions as a response to environmental stimuli. This process requires a motility structure and a system to direct the movement. For swimming motility, Archaea employ a rotating filament, the archaellum. This Archaea-specific structure is functionally equivalent, but structurally different, from the bacterial flagellum. To control the directionality of movement, some Archaea make use of the chemotaxis system, which is used for the same purpose by bacteria. Over the past decades, chemotaxis has been studied in detail in several model bacteria. In contrast, Archaeal chemotaxis is much less explored and largely restricted to analyses in halophilic Archaea. In this review, we summarize the available information on Archaeal taxis. We conclude that Archaeal chemotaxis proteins function similarly as their bacterial counterparts. However, because the motility structures are fundamentally different, an Archaea-specific docking mechanism is required, for which initial experimental data have only recently been obtained.

  • Archaeal biofilm formation
    Nature Reviews Microbiology, 2018
    Co-Authors: Marleen Wolferen, Alvaro Orell, Sonja-verena Albers


    Archaea have been found in biofilms in a variety of habitats. In this Review, Albers and colleagues explore the different stages of Archaeal biofilm development and highlight the similarities and differences between Archaea and bacteria. They also consider their role in different industrial processes. Biofilms are structured and organized communities of microorganisms that represent one of the most successful forms of life on Earth. Bacterial biofilms have been studied in great detail, and many molecular details are known about the processes that govern bacterial biofilm formation, however, Archaea are ubiquitous in almost all habitats on Earth and can also form biofilms. In recent years, insights have been gained into the development of Archaeal biofilms, how Archaea communicate to form biofilms and how the switch from a free-living lifestyle to a sessile lifestyle is regulated. In this Review, we explore the different stages of Archaeal biofilm development and highlight similarities and differences between Archaea and bacteria on a molecular level. We also consider the role of Archaeal biofilms in industry and their use in different industrial processes.

  • Versatile cell surface structures of Archaea.
    Molecular Microbiology, 2017
    Co-Authors: Paushali Chaudhury, Tessa E F Quax, Sonja-verena Albers


    Archaea are ubiquitously present in nature and colonize environments with broadly varying growth conditions. Several surface appendages support their colonization of new habitats. A hallmark of Archaea seems to be the high abundance of type IV pili (T4P). However, some unique non T4 filaments are present in a number of Archaeal species. Archaeal surface structures can mediate different processes such as cellular surface adhesion, DNA exchange, motility and biofilm formation and represent an initial attachment site for infecting viruses. In addition to the functionally characterized Archaeal T4P, Archaeal genomes encode a large number of T4P components that might form yet undiscovered surface structures with novel functions. In this review, we summarize recent advancement in structural and functional characterizations of known Archaeal surface structures and highlight the diverse processes in which they play a role.

Wf Doolittle – One of the best experts on this subject based on the ideXlab platform.

  • Phylogenetic analyses of two “Archaeal” genes in Thermotoga maritima reveal multiple transfers between Archaea and Bacteria
    Molecular Biology and Evolution, 2001
    Co-Authors: Cl Nesbo, Stéphane L'haridon, Ko Stetter, Wf Doolittle


    The genome sequence of Thermotoga maritima revealed that 24% of its open reading frames (ORFs) showed the highest similarity scores to Archaeal genes in BLAST analyses. Here we screened 16 strains from the genus Thermotoga and other related Thermotogales for the occurrence of two of these “Archaeal” genes: the gene encoding the large subunit of glutamate synthase (gltB) and the mpo-inositol 1P synthase gene (ino1). Both genes were restricted to the Thermotoga species within the Thermotogales. The distribution of the two genes, along with results from phylogenetic analyses, showed that they were acquired from Archaea during the divergence of the Thermotogales. Database searches revealed that three other bacteria-Dehalococcoides ethenogenes, Sinorhizobium meliloti, and Clostridium difficile-possess Archaeal-type gltBs, and the phylogenetic analyses confirmed at least two lateral gene transfer (LGT) events between Bacteria and Archaea. These LGT events were also strongly supported by gene structure data, as the three domains in bacterial-type gltB are homologous to three independent ORFs in Archaea and Bacteria with Archaeal-type gltBs. The ino1 gene has a scattered distribution among Bacteria, and apart from the Thermotoga strains it is found only in Aquifex aeolicus, D. ethenogenes, and some high-G + C Gram-positive bacteria. Phylogenetic analysis of the ino1 sequences revealed three highly supported prokaryotic clades, all containing a mixture of Archaeal and bacterial sequences, and suggested that all bacterial ino1 genes had been recruited from Archaeal donors. The Thermotoga strains and A. aeolicus acquired this gene independently from different Archaeal species. Although transfer of genes from hyperthermophilic Archaea may have facilitated the evolution of bacterial hyperthermophily, between-domain transfers also affect mesophilic species. For hyperthermophiles, we hypothesize that LGT may be as much a consequence as the cause of adaptation to hyperthermophily.

  • Bacterial origin for the isoprenoid biosynthesis enzyme HMG-CoA reductase of the Archaeal orders thermoplasmatales and archaeoglobales
    Molecular Biology and Evolution, 2001
    Co-Authors: Y Boucher, Ko Stetter, Stéphane L'haridon, H Huber, Wf Doolittle


    The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase or HMGR) fulfills an essential role in Archaea, as it is required for the synthesis of isoprenoid ethers, the main component of Archaeal cell membranes. There are two clearly homologous but structurally different classes of the enzyme, one found mainly in eukaryotes and Archaea (class 1), and the other found in bacteria (class 2). This feature facilitated the identification of several cases of interdomain lateral gene transfer (LGT), in particular, the bacterial origin for the HMGR gene from the archaeon Archaeoglobus fulgidus. In order to investigate if this LGT event was recent and limited in its scope of had a broad and long-term impact on the recipient and its related lineages, the HMGR gene was amplified and sequenced From a variety of Archaea. The survey covered close relatives of A. fulgidus, the only archaeon known prior to this study to possess a bacterial-like HMGR; representatives of each main euryArchaeal group were also inspected. All culturable members of the Archaeal group Archaeoglobales were found to display an HMGR very similar to the enzyme of the bacterium Pseudomonas mevalonii. Surprisingly, two species of the genus Thermoplasma also harbor an HMGR of bacterial origin highly similar to the enzymes found in the Archaeoglobales. Phylogenetic analyses of the HMGR gene and comparisons to reference phylogenies from other genes confirm a common bacterial origin for the HMGRs of Thermoplasmatales and Archaeoglobales. The most likely explanation of these results includes an initial bacteria-to-Archaea transfer, followed by a another event between Archaea. Their presence in two divergent Archaeal lineages suggests an important adaptive role for these laterally transferred genes.

Christa Schleper – One of the best experts on this subject based on the ideXlab platform.

  • Meet the relatives of our cellular ancestor
    Nature, 2020
    Co-Authors: Christa Schleper, Filipa L. Sousa


    Microorganisms called Asgard Archaea have been grown in the laboratory. Microorganisms related to lineages of the Asgard Archaea group are thought to have evolved into complex eukaryotic cells. Now the first Asgard Archaeal species to be grown in the laboratory reveals its metabolism and cell biology.

  • metagenomics of kamchatkan hot spring filaments reveal two new major hyper thermophilic lineages related to thaumarchaeota
    Research in Microbiology, 2013
    Co-Authors: Laila J Reigstad, Anja Spang, Christa Schleper, Anders Lanzen, Thomas Weinmaier, Thomas Rattei, Celine Brochierarmanet


    Based on phylogenetic analyses and gene distribution patterns of a few complete genomes, a new distinct phylum within the Archaea, the Thaumarchaeota, has recently been proposed. Here we present analyses of six Archaeal fosmid sequences derived from a microbial hot spring community in Kamchatka. The phylogenetic analysis of informational components (ribosomal RNAs and proteins) reveals two major (hyper-)thermophilic clades (“Hot Thaumarchaeota-related Clade” 1 and 2, HTC1 and HTC2) related to Thaumarchaeota, representing either deep branches of this phylum or a new Archaeal phylum and provides information regarding the ancient evolution of Archaea and their evolutionary links with Eukaryotes.

  • genomic studies of uncultivated Archaea
    Nature Reviews Microbiology, 2005
    Co-Authors: Christa Schleper, German Jurgens, Melanie Jonuscheit


    Archaea represent a considerable fraction of the prokaryotic world in marine and terrestrial ecosystems, indicating that organisms from this domain might have a large impact on global energy cycles. However, many novel Archaeal lineages that have been detected by molecular phylogenetic approaches have remained elusive because no laboratory-cultivated strains are available. Environmental genomic analyses have recently provided clues about the potential metabolic strategies of several of the uncultivated and abundant Archaeal species, including non-thermophilic terrestrial and marine crenarchaeota and methanotrophic euryarchaeota. These initial studies of natural Archaeal populations also revealed an unexpected degree of genomic variation that indicates considerable heterogeneity among Archaeal strains. Here, we review genomic studies of uncultivated Archaea within a framework of the phylogenetic diversity and ecological distribution of this domain.