Difference between Mitochondrial RNase P and Nuclear RNase P [Letters to the Editor]

[Discussion of: Puranam, R. S., and G. Attardi. 2001. The RNase P associated with HeLa cell mitochondria contains an essential RNA component identical in sequence to that of the nuclear RNase P. Mol. Cell. Biol. 21:548-561.

Localization of Human RNase Z Isoforms: Dual Nuclear/Mitochondrial Targeting of the ELAC2 Gene Product by Alternative Translation Initiation

RNase Z is an endonuclease responsible for the removal of 3′ extensions from tRNA precursors, an essential step in tRNA biogenesis. Human cells contain a long form (RNase ZL) encoded by ELAC2, and a short form (RNase ZS; ELAC1). We studied their subcellular localization by expression of proteins fused to green fluorescent protein. RNase ZS was found in the cytosol, whereas RNase ZL localized to the nucleus and mitochondria. We show that alternative translation initiation is responsible for the dual targeting of RNase ZL. Due to the unfavorable context of the first AUG of ELAC2, translation apparently also starts from the second AUG, whereby the mitochondrial targeting sequence is lost and the protein is instead routed to the nucleus. Our data suggest that RNase ZL is the enzyme involved in both, nuclear and mitochondrial tRNA 3′ end maturation

Positioning Europe for the EPITRANSCRIPTOMICS challenge

The genetic alphabet consists of the four letters: C, A, G, and T in DNA and C,A,G, and U in RNA. Triplets of these four letters jointly encode 20 different amino acids out of which proteins of all organisms are built. This system is universal and is found in all kingdoms of life. However, bases in DNA and RNA can be chemically modified. In DNA, around 10 different modifications are known, and those have been studied intensively over the past 20 years. Scientific studies on DNA modifications and proteins that recognize them gave rise to the large field of epigenetic and epigenomic research. The outcome of this intense research field is the discovery that development, ageing, and stem-cell dependent regeneration but also several diseases including cancer are largely controlled by the epigenetic state of cells. Consequently, this research has already led to the first FDA approved drugs that exploit the gained knowledge to combat disease. In recent years, the ~150 modifications found in RNA have come to the focus of intense research. Here we provide a perspective on necessary and expected developments in the fast expanding area of RNA modifications, termed epitranscriptomics.SCOPUS: no.jinfo:eu-repo/semantics/publishe

The amyloid-β-SDR5C1(ABAD) interaction does not mediate a specific inhibition of mitochondrial RNase P.

The amyloid-β peptide (Aβ) is suggested to cause mitochondrial dysfunction in Alzheimer's disease. The mitochondrial dehydrogenase SDR5C1 (also known as ABAD) was shown to bind Aβ and was proposed to thereby mediate mitochondrial toxicity, but the molecular mechanism has not been clarified. We recently identified SDR5C1 as an essential component of human mitochondrial RNase P and its associated tRNA:m¹R9 methyltransferase, the enzymes responsible for tRNA 5'-end processing and methylation of purines at tRNA position 9, respectively. With this work we investigated whether SDR5C1's role as a subunit of these two tRNA-maturation activities represents the mechanistic link between Aβ and mitochondrial dysfunction. Using recombinant enzyme components, we tested RNase P and methyltransferase activity upon titration of Aβ. Micromolar concentrations of monomeric or oligomerized Aβ were required to inhibit tRNA 5'-end processing and position 9 methylation catalyzed by the SDR5C1-containing enzymes, yet similar concentrations of Aβ also inhibited related RNase P and methyltransferase activities, which do not contain an SDR5C1 homolog. In conclusion, the proposed deleterious effect of Aβ on mitochondrial function cannot be explained by a specific inhibition of mitochondrial RNase P or its tRNA:m¹R9 methyltransferase subcomplex, and the molecular mechanism of SDR5C1-mediated Aβ toxicity remains unclear

Nucleic Acids Research / Molecular insights into HSD10 disease : impact of SDR5C1 mutations on the human mitochondrial RNase P complex

SDR5C1 is an amino and fatty acid dehydrogenase/reductase, moonlighting as a component of human mitochondrial RNase P, which is the enzyme removing 5′-extensions of tRNAs, an early and crucial step in tRNA maturation. Moreover, a subcomplex of mitochondrial RNase P catalyzes the N1-methylation of purines at position 9, a modification found in most mitochondrial tRNAs and thought to stabilize their structure. Missense mutations in SDR5C1 cause a disease characterized by progressive neurodegeneration and cardiomyopathy, called HSD10 disease. We have investigated the effect of selected mutations on SDR5C1's functions. We show that pathogenic mutations impair SDR5C1-dependent dehydrogenation, tRNA processing and methylation. Some mutations disrupt the homotetramerization of SDR5C1 and/or impair its interaction with TRMT10C, the methyltransferase subunit of the mitochondrial RNase P complex. We propose that the structural and functional alterations of SDR5C1 impair mitochondrial RNA processing and modification, leading to the mitochondrial dysfunction observed in HSD10 patients.(VLID)458980

Technique of Measuring Bunch Length by Phasing an RF Cavity.

No abstract prepared

A Simple Beam Position Monitor System for CEBAF

CEBAF is a recirculating linac where the beam passes several times through the linac structures. As a result, up to five beams of different energies may be present in the same linac vacuum chambers simultaneously. One method of distinguishing between the beams involves modulating the current for a time interval of less than one revolution period. In this paper, a very simple low cost beam position monitor system based on the detection of this modulation is presented. Initial results indicated that 1mm displacements for beam currents of 1 micro-amp can be measured. With the incorporation of several improvements to the present monitor design, the sensitivity is expected to be increased to 1 mm for a 100 nA beam

Effect of Aβ on tRNA:m¹R9 methyltransferase activity.

<p>(<b>A</b>) (mt)tRNA^Ile specifically labeled at position 9 was incubated with the TRMT10C-SDR5C1 complex in the presence of a methyl group donor and the indicated concentrations fresh Aβ₄₂ or scrambled sequence peptide. No enzyme was added to the mock reaction. The tRNA hydrolysate was resolved by TLC and visualized by phosphor imaging. The 30-minute time-point of the reactions is shown. (<b>B</b>) Product formation in experiments like that shown in (A) was quantitatively analyzed and results plotted. Data are expressed relative to control reactions, to which only the solvent had been added. Mean and SD of three or four independent experiments are shown. (<b>C</b>) The methyltransferase activity of yeast Trm10p was assayed in the presence of different concentrations of fresh Aβ or scrambled sequence peptide and the results of four independent experiments were analyzed and plotted like in (B).</p

Effect of Aβ on the dehydrogenase activity of SDR5C1.

<p>L-3-hydroxyacyl-CoA dehydrogenase activity of SDR5C1 was measured with acetoacetyl-CoA as substrate and in presence of either (<b>A</b>) freshly dissolved or (<b>B</b>) “<i>in vitro</i> aged”, oligomeric (oligo) preparations of Aβ₄₂ or scrambled sequence peptide (scr). Data are expressed relative to the activity of control reactions, to which only the solvent had been added. Mean and SD of two (A) and three (B) independent experiments are shown.</p