| 词条 | MalK RNA motifs |
| 释义 |
They are defined by being consistently located upstream of malK genes, which encode an ATPase that is used by transporters whose ligand is likely a kind of sugar. Most of these genes are annotated either as transporting maltose or glycerol-3-phosphate, however the substrate of the transporters associated with malK motif RNAs has not been experimentally determined. All known types of malK RNA motif are generally located nearby to the Shine-Dalgarno sequence of the downstream gene. Given their positions upstream of genes and proximal to Shine-Dalgarno sequences, malK RNA motifs likely function as cis-regulatory elements, to regulate their associated malK genes. It is possible that they bind a sugar directly, and therefore function as riboswitches, but it is equally possible that regulation is mediated via a protein factor, or some other mechanism. Three class of malK RNA motif have been found, and each class exhibits a completely unrelated structure, in terms of different conserved sequence features and a different conserved secondary structure. malK-I motifs are found in Clostridia, while malK-II motifs are found in organisms within the genus Vibrio. malK-III motifs have not yet (as of 2018) been identified in any classified organism, but are known only from sequences isolated from metagenomic environmental samples. References1. ^{{cite journal |vauthors=Weinberg Z, Lünse CE, Corbino KA, Ames TD, Nelson JW, Roth A, Perkins KR, Sherlock ME, Breaker RR |title=Detection of 224 candidate structured RNAs by comparative analysis of specific subsets of intergenic regions |journal=Nucleic Acids Res. |volume=45 |issue=18 |pages=10811–10823 |date=October 2017 |pmid=28977401 |pmc=5737381 |doi=10.1093/nar/gkx699 |url=}} {{Navbox| name = hide the gallery | title = Gallery of MalK RNA motifs | titlestyle = background:#e7dcc3 | state = autocollapse | list1 = {{Gallery | lines=1 | Image:RF03069.svg|malK-I Secondary structure taken from the Rfam database. Family RF03069 | Image:RF03008.svg|malK-II Secondary structure taken from the Rfam database. Family RF03008 | Image:RF03009.svg|malK-III Secondary structure taken from the Rfam database. Family RF03009 }} }} 1 : Non-coding RNA |
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