Project description:During nuclear surveillance, the RNA exosome functions together with the TRAMP complexes, which include the RNA helicase Mtr4 together with a RNA binding protein (Air1 or Air2) and a poly(A) polymerase (Trf4 or Trf5). To better determine how RNA substrates are targeted, we analyzed protein and RNA interactions by TRAMP components. Mass spectrometry identified three distinct TRAMP complexes formed in vivo. These complexes preferentially assemble on different classes of transcripts. Unexpectedly, on many substrates, including pre-rRNAs and pre-mRNAs, specificity was apparently conferred by Trf4 and Trf5. Clustering of mRNAs by TRAMP association showed co-enrichment for mRNAs with functionally related products, supporting the significance of surveillance in regulating gene expression. Comparison of the binding sites of TRAMP components with multiple nuclear RNA binding proteins revealed preferential colocalization of subsets of factors. On pre-mRNAs, ∆trf5 deletion caused reduced Mtr4 binding and RNA accumulation of Trf5 top targets.
Project description:During nuclear surveillance in yeast, the RNA exosome functions together with the TRAMP complexes. These include the DEAH-box RNA helicase Mtr4 together with an RNA-binding protein (Air1 or Air2) and a poly(A) polymerase (Trf4 or Trf5). To better determine how RNA substrates are targeted, we analyzed protein and RNA interactions for TRAMP components. Mass spectrometry identified three distinct TRAMP complexes formed in vivo. These complexes preferentially assemble on different classes of transcripts. Unexpectedly, on many substrates, including pre-rRNAs and pre-mRNAs, binding specificity was apparently conferred by Trf4 and Trf5. Clustering of mRNAs by TRAMP association showed coenrichment for mRNAs with functionally related products, supporting the significance of surveillance in regulating gene expression. We compared binding sites of TRAMP components with multiple nuclear RNA binding proteins, revealing preferential colocalization of subsets of factors. TRF5 deletion reduced Mtr4 recruitment and increased RNA abundance for mRNAs specifically showing high Trf5 binding.
Project description:The Saccharomyces cerevisiae TRAMP4 and TRAMP5 complexes, which consist of the poly(A) polymerase Trf4 or Trf5, respectively, the zinc knuckle proteins Air1 or Air2, and the RNA helicase Mtr4, play a critical role in nuclear RNA surveillance. Although it is known to enhance the nuclease activity of the exosome, relatively little is known about the exact mechanism and specificity of TRAMP. To better define the specificities of the TRAMP complexes, we used phenotypic analysis and RNA deep-sequencing technology to measure differences in global RNA polyadenylation in air mutants, revealing specific requirements for each Air protein in the regulation of the levels of non-coding and coding RNAs. These findings reveal differential functions for Air proteins in eukaryotic RNA metabolism and indicate that they control the substrate specificity of the RNA exosome. Poly(A)+ RNA from WT, rrp6-M-NM-^T, air1-M-NM-^T rrp6-M-NM-^T and air2-M-NM-^T rrp6-M-NM-^T was sequenced using ABI SOLiD platform, in duplicate.
Project description:The Saccharomyces cerevisiae TRAMP4 and TRAMP5 complexes, which consist of the poly(A) polymerase Trf4 or Trf5, respectively, the zinc knuckle proteins Air1 or Air2, and the RNA helicase Mtr4, play a critical role in nuclear RNA surveillance. Although it is known to enhance the nuclease activity of the exosome, relatively little is known about the exact mechanism and specificity of TRAMP. To better define the specificities of the TRAMP complexes, we used phenotypic analysis and RNA deep-sequencing technology to measure differences in global RNA polyadenylation in air mutants, revealing specific requirements for each Air protein in the regulation of the levels of non-coding and coding RNAs. These findings reveal differential functions for Air proteins in eukaryotic RNA metabolism and indicate that they control the substrate specificity of the RNA exosome.
Project description:Abstract: Quality control requires discrimination between functional and aberrant species to selectively target substrates for destruction. Nuclear RNA quality control in Saccharomyces cerevisiae includes the TRAMP complex that marks RNA for decay via polyadenylation and helicase-dependent 3′ to 5′ degradation by the RNA exosome. Using reconstitution biochemistry we show that polyadenylation and helicase activities of TRAMP cooperate with processive and distributive exoribonuclease activities of the nuclear RNA exosome to selectively target and degrade an unmodified tRNA while leaving native tRNA intact. Inactivation of the distributive exoribonuclease activity of Rrp6 results in loss of substrate discrimination, leading to degradation of all RNAs. These data suggest that the activities of the Mtr4 helicase and Rrp6 exoribonuclease endow the TRAMP-RNA exosome complex with the ability to protect stable RNA while degrading defective RNA species. Rrp6 and its 3′-5′ exonuclease activity have previously been shown to contribute to quality control and processing of various types of nuclear RNAs. Our sequencing analysis further confirms that Rrp6 contributes to this process.
Project description:Purpose: The goal of this study is to compare RNA-seq libraries of wildtype Caulobacter crescentus with two lon deletion strains (delta lon and delta lon clpX*). Methods: See Methods section of "Plasticity in AAA+ proteases reveals substrate specificity niches" for information regarding methods or contact lead correspondence. Briefly, Samples for RNAseq were extracted from wt and lon deletion strains grown to stationary phase. Conclusions: Our study represents the first detailed analysis of lon deletions (delta lon and delta lon clpX*) comparison to wt caulobacter transcriptomes, with biologic replicates, generated by RNA-seq technology in stationary phas