title: Self-circularizing 5'-ETS RNAs accumulate along with unprocessed pre ribosomal RNAs in growth-stressed Entamoeba histolytica.
abstract: The primary transcript of rRNA genes is a large pre rRNA which is precisely processed to release the mature rRNAs. The 5'-external transcribed spacer (ETS) of rRNA genes contains important sites for pre rRNA processing. Once the processing is accomplished the ETS is rapidly degraded. We show that in growth-stressed cells of the human parasitic protist Entamoeba histolytica the A'-A(0) sub-fragment of the 5'-ETS accumulates to high levels as a family of RNA molecules of size 666 to 912 nt. These etsRNAs are circular in vivo and can spontaneously self-circularize in vitro. The accumulation of etsRNAs is accompanied by accumulation of unprocessed pre rRNA, indicating a possible role of etsRNAs in inhibition of processing during growth stress. Our data shows for the first time that processed etsRNA is not a mere by-product destined for degradation but is stabilized by circularization and could play a regulatory role as noncoding RNA.
authors.affiliation: School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Abhishek Kumar
authors.initials: AK
authors.lastname: Gupta
authors.forename: Sunil Kumar
authors.initials: SK
authors.lastname: Panigrahi
authors.forename: Alok
authors.initials: A
authors.lastname: Bhattacharya
authors.forename: Sudha
authors.initials: S
authors.lastname: Bhattacharya
mesh_terms: D000818:Animals; D004748:Entamoeba histolytica / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012335:RNA, Ribosomal / Q000235:genetics*
chemical_list: D012335:RNA, Ribosomal