Fig. 1: Structures of the human mitochondrial tRNA maturation complexes.
From: Structural basis for human mitochondrial tRNA maturation
a Secondary structure of pre-tRNAIle and pre-tRNAHis-Ser, the 5′-leader and 3′-trailer are indicated in orange, tRNASer(AGY) is the 3′-trailer of tRNAHis. The sequence of the other pre-tRNAs used in this study and the nucleotide numbering used in the atomic coordinates deposited in the PDB are shown in Supplementary Fig. 1a. The maturation sites of the enzymes studied here are indicated. b Domain organisations of TRMT10C, SDR5C1, PRORP, ELAC2 and TRNT1; MTS: mitochondrial transport signal, NTD: N-terminal domain, MTase: methyltransferase, PPR: pentatrico-peptide repeat, CD: central domain. c Activity assays of reconstituted complexes showing methylation of pre-tRNAIle and pre-tRNAHis-Ser by the TRMT10C/SDR5C1 complex, processing of pre-tRNAHis-Ser by PRORP, processing of pre-tRNAHis(0,Ser) by ELAC2 and 3′-CCA addition to tRNAIle by TRNT1 when pre-tRNAs are bound to the TRMT10C/SDR5C1 complex, PRORPD479A and ELAC2H548A are not active. pre-tRNAHis(0,Ser) has no 5′-leader sequence, Blk is an assay without TRMT10C/SDR5C1. Marker M1 is pre-tRNAHis-Ser (133 nucleotides, nt), M2 is pre-tRNAHis(0,Ser) (128 nt) and M3 is tRNAIle (69 nt). Source data are provided as a Source Data file. For methylation assay, error bars represent standard deviation, n = 3 technical replicates, gels are representative of three experiments. d Cryo-EM density map and refined model of the complex responsible for human mitochondrial tRNA G9 N1-methylation, composed of TRMT10C(SAH)/SDR5C1(NADH)/pre-tRNAIle (Complex 1). e Composite map and refined model of the human mitochondrial RNase P with pre-tRNAHis-Ser, composed of TRMT10C(SAH)/SDR5C1(NADH)/pre-tRNAHis-Ser/PRORPD479A (Complex 2). f Composite map and refined model of the human mitochondrial RNase Z with pre-tRNAHis(0,Ser), composed of TRMT10C(SAH)/SDR5C1(NADH)/pre-tRNAHis(0,Ser)/ELAC2H548A (Complex 3). g Composite map and refined model of the complex responsible for the human mitochondrial tRNA 3’-CCA addition, composed of TRMT10C(SAH)/SDR5C1(NADH)/RNAIle/TRNT1/CDP (Complex 4). Domains of enzymes are colored as in b.
