In
taxonomy
Taxonomy is the practice and science of categorization or classification.
A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. A ...
, the Sulfolobales are an
order of the
Thermoprotei
The Thermoprotei is a class of the Thermoproteota.
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information
The National Cen ...
.
Phylogeny
The currently accepted taxonomy is based on the
List of Prokaryotic names with Standing in Nomenclature
List of Prokaryotic names with Standing in Nomenclature (LPSN) is an online database that maintains information on the naming and taxonomy of prokaryotes, following the taxonomy requirements and rulings of the International Code of Nomenclature o ...
(LPSN)
and
National Center for Biotechnology Information
The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The ...
(NCBI)
DNA transfer
Exposure of ''Sulfolobus solfataricus'' to the DNA damaging agents
UV-irradiation,
bleomycin
-13- (1''H''-imidazol-5-yl)methyl9-hydroxy-5- 1''R'')-1-hydroxyethyl8,10-dimethyl-4,7,12,15-tetraoxo-3,6,11,14-tetraazapentadec-1-yl}-2,4'-bi-1,3-thiazol-4-yl)carbonyl]amino}propyl)(dimethyl)sulfonium
, chemical_formula =
, C=55 , H=84 , N=1 ...
or
Mitomycins, mitomycin C induces cellular aggregation.
Other physical stressors, such as pH or temperature shift, do not induce aggregation, suggesting that induction of aggregation is caused specifically by DNA damage. Ajon et al.
showed that UV-induced cellular aggregation mediates chromosomal marker exchange with high frequency. Recombination rates exceeded those of uninduced cultures by up to three orders of magnitude. Frols et al.
and Ajon et al.
hypothesized that the UV-inducible DNA transfer process and subsequent
homologous recombination
Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in cellular organisms but may be ...
al repair represents an important mechanism to maintain chromosome integrity. This response may be a primitive form of sexual interaction, similar to the more well-studied bacterial transformation that is also associated with DNA transfer between cells leading to homologous recombinational repair of DNA damage. In another related species, ''Sulfolobus acidocaldarius'', UV-irradiation also increases the frequency of recombination due to genetic exchange.
The ''ups'' operon
The ''ups'' (UV-induced pilus) operon of ''Sulfolobus'' species is highly induced by UV irradiation. The
pili encoded by this operon are employed in promoting cellular aggregation, which is necessary for subsequent DNA exchange between cells, resulting in
homologous recombination
Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in cellular organisms but may be ...
.
[
A study of the ''Sulfolobales acidocaldarius ups'' operon showed that one of the genes downstream of the operon, ''saci-1497'', encodes an ]endonuclease
Endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain. Some, such as deoxyribonuclease I, cut DNA relatively nonspecifically (without regard to sequence), while many, typically called restriction endonucleases ...
III that nicks UV-damaged DNA; and another gene of the operon, ''saci-1500'', encodes a RecQ-like helicase that is able to unwind homologous recombination intermediates such as Holliday junction
A Holliday junction is a branched nucleic acid structure that contains four double-stranded arms joined. These arms may adopt one of several conformations depending on buffer salt concentrations and the sequence of nucleobases closest to the ju ...
s.
References
Further reading
Scientific journals
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Scientific books
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Scientific databases
External links
{{Taxonbar, from=Q1046960
Archaea taxonomic orders
Thermoproteota