A subcomplex of human mitochondrial RNase P is a bifunctional methyltransferase--extensive moonlighting in mitochondrial tRNA biogenesis.

Transfer RNAs (tRNAs) reach their mature functional form through several steps of processing and modification. Some nucleotide modifications affect the proper folding of tRNAs, and they are crucial in case of the non-canonically structured animal mitochondrial tRNAs, as exemplified by the apparently ubiquitous methylation of purines at position 9. Here, we show that a subcomplex of human mitochondrial RNase P, the endonuclease removing tRNA 5' extensions, is the methyltransferase responsible for m(1)G9 and m(1)A9 formation.

Nuclear RNase P of Trypanosoma brucei: a single protein in place of the multicomponent RNA-protein complex.

RNase P is the endonuclease that removes 5' extensions from tRNA precursors. In its best-known form, the enzyme is composed of a catalytic RNA and a protein moiety variable in number and mass. This ribonucleoprotein enzyme is widely considered ubiquitous and apparently reached its highest complexity in the eukaryal nucleus, where it is typically composed of at least ten subunits.

Maternally inherited essential hypertension is associated with the novel 4263A>G mutation in the mitochondrial tRNAIle gene in a large Han Chinese family.

Rationale: Despite maternal transmission of hypertension in some pedigrees, pathophysiology of maternally inherited hypertension remains poorly understood.

Objective: To establish a causative link between mitochondrial dysfunction and essential hypertension.

Method And Results: A total of 106 subjects from a large Chinese family underwent clinical, genetic, molecular, and biochemical evaluations.

A single Arabidopsis organellar protein has RNase P activity.

The ubiquitous endonuclease RNase P is responsible for the 5' maturation of tRNA precursors. Until the discovery of human mitochondrial RNase P, these enzymes had typically been found to be ribonucleoproteins, the catalytic activity of which is associated with the RNA component. Here we show that, in Arabidopsis thaliana mitochondria and plastids, a single protein called 'proteinaceous RNase P' (PRORP1) can perform the endonucleolytic maturation of tRNA precursors that defines RNase P activity.

RNA-regulated interaction of transportin-1 and exportin-5 with the double-stranded RNA-binding domain regulates nucleocytoplasmic shuttling of ADAR1.

Double-stranded RNA (dsRNA)-binding proteins interact with substrate RNAs via dsRNA-binding domains (dsRBDs). Several proteins harboring these domains exhibit nucleocytoplasmic shuttling and possibly remain associated with their substrate RNAs bound in the nucleus during nuclear export. In the human RNA-editing enzyme ADAR1-c, the nuclear localization signal overlaps the third dsRBD, while the corresponding import factor is unknown.

RNA aptamers binding the double-stranded RNA-binding domain.

Specific RNA recognition of proteins containing the double-strand RNA-binding domain (dsRBD) is essential for several biological pathways such as ADAR-mediated adenosine deamination, localization of RNAs by Staufen, or RNA cleavage by RNAse III. Structural analysis has demonstrated the lack of base-specific interactions of dsRBDs with either a perfect RNA duplex or an RNA hairpin. We therefore asked whether in vitro selections performed in parallel with individual dsRBDs could yield RNAs that are specifically recognized by the dsRBD on which they were selected .