C1D and hMtr4p associate with the human exosome subunit PM/Scl-100 and are involved in pre-rRNA processing

Abstract

The exosome is a complex of 3′–5′ exoribonucleases and RNA-binding proteins, which is involved in processing or degradation of different classes of RNA. Previously, the characterization of purified exosome complexes from yeast and human cells suggested that C1D and KIAA0052/hMtr4p are associated with the exosome and thus might regulate its functional activities. Subcellular localization experiments demonstrated that C1D and KIAA0052/hMtr4p co-localize with exosome subunit PM/Scl-100 in the nucleoli of HEp-2 cells. Additionally, the nucleolar accumulation of C1D appeared to be dependent on PM/Scl-100. Protein–protein interaction studies showed that C1D binds to PM/Scl-100, whereas KIAA0052/hMtr4p was found to interact with MPP6, a previously identified exosome-associated protein. Moreover, we demonstrate that C1D, MPP6 and PM/Scl-100 form a stable trimeric complex in vitro. Knock-down of C1D, MPP6 and KIAA0052/hMtr4p by RNAi resulted in the accumulation of 3′-extended 5.8S rRNA precursors, showing that these proteins are required for rRNA processing. Interestingly, C1D appeared to contain RNA-binding activity with a potential preference for structured RNAs. Taken together, our results are consistent with a role for the exosome-associated proteins C1D, MPP6 and KIAA052/hMtr4p in the recruitment of the exosome to pre-rRNA to mediate the 3′ end processing of the 5.8S rRNA.

Exosome Cofactors Connect Transcription Termination to RNA Processing by Guiding Terminated Transcripts to the Appropriate Exonuclease within the Nuclear Exosome

“…4A). This suggests that a stable Mpp6-Rrp6-Rrp47 complex can assemble as previously shown in vitro using human proteins (34). Importantly, the region (MC-2) within Mpp6 that binds to the Nrd1 CID turns out to mediate the interaction with Rrp6 as well (Fig.…”

“…Mpp6 Interacts with Rrp6 -Human Mpp6 interacts directly with PM-Scl100 (human Rrp6) by Y2H and co-IP experiments (33,34). We consistently found that yeast Mpp6 also interacts with Rrp6 by Y2H assay (Fig.…”

“…For instance, Mpp6 may interact with Mtr4 as seen in human cells (33,34) and thus still indirectly stimulate the activity of Rrp6. To make it clear, our results do not exclude the role of Mpp6 in Rrp6-mediated processing of various RNA substrates.…”

Rrp6, Rrp47 and Cofactors of the Nuclear Exosome

“…11,14,64,65 Research on Rrp47 has focussed on its physical association with the exosome nuclease complex. …”

Ethylnitrosourea‐induced thymus‐defective mutants identify roles ofKIAA1440, TRRAP, andSKIV2L2in teleost organ development

“…SKIV2L2 is also associated with the human exosome subunit PM/ Scl-100 and is involved in pre-rRNA processing [36]. Medaka SKIV2L2 encodes a protein of 1036 amino acid residues, whereas the hjc mutation presumably produces a mutant protein containing 366 amino acid residues of SKIV2L2 N-terminus and four amino acid residues derived from the intron.…”