|
RyhB RNA is a 90 nucleotide non-coding RNA that down-regulates a set of iron-storage and iron-using proteins when iron is limiting; it is itself negatively regulated by the ferric uptake repressor protein, Fur (Ferric uptake regulator). This ncRNA gene was independently identified in two screens, named RyhB by Wasserman ''et al''. and called SraI by Argaman ''et al''. and was found to be expressed only in stationary phase. RyhB RNA levels are inversely correlated with mRNA levels for the ''sdhCDAB'' operon, encoding succinate dehydrogenase, as well as five other genes previously shown to be positively regulated by Fur by an unknown mechanism. These include two other genes encoding enzymes in the tricarboxylic acid cycle, ''acnA'' and ''fumA'', two ferritin genes, ''ftnA'' and ''bfr'', and a gene for superoxide dismutase, ''sodB''. A number of other genes have been predicted computationally and verified as targets by microarray analysis: ''napF'', ''sodA'', ''cysE'', ''yciS'', ''acpS'', ''nagZ'' and ''dadA''. RyhB is bound by the Hfq protein, that increases its interaction with its target messages. A comparative genomics target prediction approach suggests that the mRNAs of eleven additional iron containing proteins are controlled by RyhB in ''Escherichia coli''. Two of those (''erpA'', ''nirB'') and two additional targets that are not directly related to iron (''nagZ'', ''marA'') were verified with a GFP reporter system. It has been shown that RyhB has a role in targeting the polycistronic transcript iscRSUA for differential degradation. RyhB binds to the second cistron of iscRSUA, which encodes machinery for biosynthesis of Fe-S clusters. This binding promotes cleavage of the downstream iscSUA transcript. This cleavage leaves the 5' IscR transcript which is a transcriptional regulator responsible regulating several genes that depend on cellular Fe-S level. RyhB is an analog of the sRNA PrrF RNA found in ''Pseudomonas aeruginosa''. ==Naming== The RyhB gene name is an acronym composed of R for RNA, y for unknown function (after the protein naming convention), with the h representing the ten-minute-interval section of the ''E. coli'' map the gene is found in. The B comes from the fact that this was one of two RNA genes identified in this interval.〔 Other RNAs using this nomenclature include RydB RNA, RyeB RNA, RyeE RNA and RyfA RNA. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「RyhB RNA」の詳細全文を読む スポンサード リンク
|