PreQ1-II Riboswitch on:
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PreQ1-II riboswitches form a class of 
riboswitch
In molecular biology, a riboswitch is a regulatory segment of a messenger RNA molecule that binds a small molecule, resulting in a change in Translation (biology), production of the proteins encoded by the mRNA. Thus, an mRNA that contains a ribo ...
es that specifically bind pre-queuosine1 (PreQ1), a precursor of the modified nucleoside queuosine
Queuosine is a modified nucleoside that is present in certain tRNAs in bacteria and eukaryotes. It contains the nucleobase queuine. Originally identified in ''E. coli'', queuosine was found to occupy the first anticodon position of tRNAs for his ...
. They are found in certain species of ''Streptococcus
''Streptococcus'' is a genus of gram-positive spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs along a sing ...
'' and ''Lactococcus
''Lactococcus'', from Latin 'lac', meaning "milk", and Ancient Greek κόκκος (''kókkos''), meaning "sphere", is a genus of lactic acid bacteria that were formerly included in the genus ''Streptococcus'' Group N1. They are known as homoferme ...
'', and were originally identified as a conserved RNA secondary structure called the "COG4708 motif". All known members of this riboswitch class appear to control members of COG4708 genes. These genes are predicted to encode membrane-bound proteins and have been proposed to be a transporter of preQ1, or a related metabolite, based on their association with preQ1-binding riboswitches. PreQ1-II riboswitches have no apparent similarities in sequence or structure to preQ1-I riboswitches, a previously discovered class of preQ1-binding riboswitches. PreQ1 thus joins S-adenosylmethionine
''S''-Adenosyl methionine (SAM), also known under the commercial names of SAMe, SAM-e, or AdoMet, is a common cosubstrate involved in methyl group transfers, transsulfuration, and aminopropylation. Although these anabolic reactions occur throug ...
as the second metabolite to be found that is the ligand of more than one riboswitch class.
References
External links
* Cis-regulatory RNA elements Riboswitch {{molecular-cell-biology-stub