User:TingGu81/Nanoarchaeota

Nanoarchaeota (Greek, "dwarf or tiny ancient one") are a phylum of the Archaea. This phylum currently has only one representative, Nanoarchaeum equitans (N. equitans). Nanoarcheaota were first discovered in 2002 in a submarine hydrothermal vent (Huver et al., 2002).

Taxonomy
Despite its small size and limited genomic repertoire, N. equitans has unique metabolic features and has been found to have a highly complex molecular machinery for intercellular communication with its host.

53 marker proteins based GTDB 07-RS207 phylogeny.

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI).


 * Class Nanobdellia Kato et al. 2022
 * Order Nanobdellales Kato et al. 2022
 * Family Nanobdellaceae Kato et al. 2022
 * Genus Nanobdella Kato et al. 2022
 * N. aerobiophila Kato et al. 2022
 * Class "Nanoarchaeia" Vazquez-Campos et al. 2021 ["Nanoarchaea" Huber et al. 2011 ]
 * Order "Nanoarchaeales" Huber et al. 2011
 * Family "Nanoarchaeaceae" Huber et al. 2011
 * Genus "Nanoarchaeum" Huber et al. 2002
 * "N. equitans" Huber et al. 2002
 * Family "Nanopusillaceae" Huber et al. 2011
 * Genus "Candidatus Nanoclepta" St. John et al. 2019
 * "Ca. N. minuta" St. John et al. 2019
 * Genus "Candidatus Nanopusillus" Wurch et al. 2016
 * "Ca. N. acidilobi" Wurch et al. 2016
 * "Ca. N. stetteri" (Castelle et al. 2015) Rinke et al. 2020
 * Order "Tiddalikarchaeales" Vazquez-Campos et al. 2021
 * Family "Tiddalikarchaeaceae" Vazquez-Campos et al. 2021
 * Genus "Candidatus Tiddalikarchaeum" Vazquez-Campos et al. 2021
 * "Ca. T. anstoanum" Vazquez-Campos et al. 2021
 * Order "Parvarchaeales" Rinke et al. 2020
 * Family "Acidifodinimicrobiaceae" Luo et al. 2020
 * Genus "Candidatus Acidifodinimicrobium" Luo et al. 2020
 * "Ca. A. mancum" Luo et al. 2020
 * Family "Parvarchaeaceae" Rinke et al. 2020 (ARMAN 4 & 5)
 * Genus "Candidatus Parvarchaeum" Baker et al. 2010
 * "Ca. P. acidiphilum" Baker et al. 2010
 * "Ca. P. paracidiphilum" corrig. Baker et al. 2010

Phylogeny
The phylogeny of the Nanoarchaeota is highly related to a representative genus, Nanoarchaeum equitans. N. equitans is confirmed to be a separate part in a phylogenetic tree different from the Crenarchaeota and Euryarchaeota lineages. Further analysis has shown that N. equitans diverged early on in the evolution of Archaea, as indicated by the 16S rRNA sequence. This suggests that they occupy a deeply branching position within this group.

Habitat
Nanoarchaeota are obligate symbionts that grow attached to an archaeal host known as Ignicoccus (Huver et al., 2002). Both terrestrial hot springs and underwater hydrothermal vents have yielded Nanoarchaeum isolates (amils). However, there is proof that Nanoarcheota reside in a variety of habitats outside of marine thermal vents (Munson-McGee et al., 2015). Genetic evidence of Nanoarchaeota has been discovered to be pervasive in terrestrial hot springs and mesophilic hypersaline habitat using primers created from the 16S rRNA gene of Nanoarchaeum equitans (N. equitans) (Munson-McGee et al., 2015). In addition, the discovery f ribosmoal sequences in photic-zone water samples taken distant from hydrothermal vents raises the possibility that Nanoarcheota are an ubiquitous and diversified class of Archaea that can live in habitats with a variety of temperatures and geochemical settings (Munson-McGee et al., 2015).

Characteristics
N. equitans cells are spherical with a diameter of approximately 400 nm (Huver et al., 2002). N. equitans has a very short and compact DNA sequence with the entire genome containing only 490,885 base pairs (Waters et al., 2003). While they have the genetic code to carry out processing and repair, they cannot carry out certain biosynthetic and metabolic processes such as lipid, amino acid, cofactor, or nucleotide synthesis (Waters et al., 2003). Due to its limited machinery, it is an obligate parasite, the only one known in the Archaeal kingdom (Waters et al., 2003). Because of their unusual ss rRNA sequences, they are difficult to detect using standard polymerase chain reaction methods (Huver et al., 2002). N. equitans contain a normal S-layer with sixfold symmetry with a 15nm lattice constant (Huver et al., 2002).

Metabolism
Although Nanoarchaeota metabolism is unknown, its host is an autotroph that grows on elemental sulphur as an electron acceptor and H2 as an electron giver (Amils). The majority of recognized metabolic processes, such as the creation of monomers like amino acids, nucleotides, and coenzymes, lack recognizable genes in this organism (amils).