Ribosome biogenesis requires a highly diverged XRN family 5'->3' exoribonuclease for rRNA processing in Trypanosoma brucei.
Ribosome biogenesis requires a highly diverged XRN family 5'->3' exoribonuclease for rRNA processing in Trypanosoma brucei.
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DOI：
10.1261/rna.038547.113
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发表时间：
2013-10
期刊：
影响因子：
--
通讯作者：
Read LK
中科院分区：
文献类型：
--
作者：
Sakyiama J;Zimmer SL;Ciganda M;Williams N;Read LK
This paper describes the identification of an exonuclease in a kinetoplastid that is related to the XRN family of exonucleases present in higher eukaryotes. Functional studies demonstrate that knockdown of this exonuclease is not lethal but results in defects in rRNA processing. Although biogenesis of ribosomes is a crucial process in all organisms and is thus well conserved, Trypanosoma brucei ribosome biogenesis, of which maturation of rRNAs is an early step, has multiple points of divergence. Our aim was to determine whether in the processing of the pre-rRNA precursor molecule, 5′→3′ exoribonuclease activity in addition to endonucleolytic cleavage is necessary in T. brucei as in other organisms. Our approach initiated with the bioinformatic identification of a putative 5′→3′ exoribonuclease, XRNE, which is highly diverged from the XRN2/Rat1 enzyme responsible for rRNA processing in other organisms. Tagging this protein in vivo allowed us to classify XRNE as nucleolar by indirect immunofluorescence and identify by copurification interacting proteins, many of which were ribosomal proteins, ribosome biogenesis proteins, and/or RNA processing proteins. To determine whether XRNE plays a role in ribosome biogenesis in procyclic form cells, we inducibly depleted the protein by RNA interference. This resulted in the generation of aberrant preprocessed 18S rRNA and 5′ extended 5.8S rRNA, implicating XRNE in rRNA processing. Polysome profiles of XRNE-depleted cells demonstrated abnormal features including an increase in ribosome small subunit abundance, a decrease in large subunit abundance, and defects in polysome assembly. Furthermore, the 5′ extended 5.8S rRNA in XRNE-depleted cells was observed in the large subunit, monosomes, and polysomes in this gradient. Therefore, the function of XRNE in rRNA processing, presumably due to exonucleolytic activity very early in ribosome biogenesis, has consequences that persist throughout all biogenesis stages.
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DOI：
10.1083/jcb.136.4.761
发表时间：
1997-02-24
期刊：
The Journal of cell biology
影响因子：
--
作者：
Bashkirov VI;Scherthan H;Solinger JA;Buerstedde JM;Heyer WD
通讯作者：
Heyer WD
影响因子：
4.5
作者：
Hashimi, Hassan;Zikova, Alena;Lukes, Julius
通讯作者：
Lukes, Julius
影响因子：
4.5
作者：
Fang, F;Phillips, S;Butler, JS
通讯作者：
Butler, JS
影响因子：
14.9
作者：
Hartshorne, T;Toyofuku, W
通讯作者：
Toyofuku, W
影响因子：
5.8
作者：
Craig, R;Beavis, RC
通讯作者：
Beavis, RC