Identification of EhTIF-IA: The putative E. histolytica orthologue of the human ribosomal RNA transcription initiation factor-IA.
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Date
2016-03
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Abstract
Initiation of rDNA transcription requires the assembly of a specific multi-protein complex at the rDNA promoter
containing the RNA Pol I with auxiliary factors. One of these factors is known as Rrn3P in yeast and Transcription
Initiation Factor IA (TIF-IA) in mammals. Rrn3p/TIF-IA serves as a bridge between RNA Pol I and the pre-initiation
complex at the promoter. It is phosphorylated at multiple sites and is involved in regulation of rDNA transcription in a
growth-dependent manner. In the early branching parasitic protist Entamoeba histolytica, the rRNA genes are present
exclusively on circular extra chromosomal plasmids. The protein factors involved in regulation of rDNA transcription
in E. histolytica are not known. We have identified the E. histolytica equivalent of TIF-1A (EhTIF-IA) by homology
search within the database and was further cloned and expressed. Immuno-localization studies showed that EhTIF-IA
co-localized partially with fibrillarin in the peripherally localized nucleolus. EhTIF-IA was shown to interact with the
RNA Pol I-specific subunit RPA12 both in vivo and in vitro. Mass spectroscopy data identified RNA Pol I-specific
subunits and other nucleolar proteins to be the interacting partners of EhTIF-IA. Our study demonstrates for the first
time a conserved putative RNA Pol I transcription factor TIF-IA in E. histolytica.
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Keywords
Entamoeba histolytica, Nucleolus, rDNA, RNA polymerase I, rRNA transcription
Citation
Srivastava Ankita, Bhattacharya Alok, Bhattacharya Sudha, Jhingan Gagan Deep. Identification of EhTIF-IA: The putative E. histolytica orthologue of the human ribosomal RNA transcription initiation factor-IA. Journal of Biosciences. 2016 Mar; 41(1): 51-62.