Sissler, M. | bioRxiv Science

bioRxiv2024

AARS Online: a collaborative database on the structure, function, and evolution of the aminoacyl-tRNA synthetases

The aminoacyl-tRNA synthetases (aaRS) are a large group of enzymes that implement the genetic code in all known biological systems. They attach amino acids to their cognate tRNAs, moonlight in various non-translational activities, and are linked to many genetic disorders. The aaRS have a subtle ontology characterized by structural and functional idiosyncrasies that vary from organism to organism, and protein to protein. Across the tree of life, the twenty-two coded amino acids are handled by sixteen evolutionary Families of Class I aaRS and twenty-one Families of Class II aaRS. We introduce AARS Online, an interactive Wikipedia-like tool curated by an international consortium of field experts. This platform systematizes existing knowledge about the aaRS by showcasing a taxonomically diverse selection of aaRS sequences and structures. Through its graphical user interface, AARS Online facilitates a seamless exploration between protein sequence and structure, providing a friendly introduction to the material for non-experts and a useful resource for experts. Curated multiple sequence alignments can be extracted for downstream analyses. Accessible at www.aars.online, AARS Online is a free resource to delve into the world of the aaRS.

biochemistry↗

bioRxiv2020

Structure of the full kinetoplastids mitoribosome and insight on its large subunit maturation

Kinetoplastids are unicellular eukaryotic parasites responsible for human pathologies such as Chagas disease, sleeping sickness or Leishmaniasis1. They possess a single large mitochondrion, essential for the parasite survival2. In kinetoplastids mitochondrion, most of the molecular machineries and gene expression processes have significantly diverged and specialized, with an extreme example being their mitochondrial ribosomes3. These large complexes are in charge of translating the few essential mRNAs encoded by mitochondrial genomes4,5. Structural studies performed in Trypanosoma brucei already highlighted the numerous peculiarities of these mitoribosomes and the maturation of their small subunit3,6. However, several important aspects mainly related to the large subunit remain elusive, such as the structure and maturation of its ribosomal RNA3. Here, we present a cryo-electron microscopy study of the protozoans Leishmania tarentolae and Trypanosoma cruzi mitoribosomes. For both species, we obtained the structure of their mature mitoribosomes, complete rRNA of the large subunit as well as previously unidentified ribosomal proteins. Most importantly, we introduce the structure of an LSU assembly intermediate in presence of 16 identified maturation factors. These maturation factors act both on the intersubunit and solvent sides of the LSU, where they refold and chemically modify the rRNA and prevent early translation before full maturation of the LSU.Competing Interest StatementThe authors have declared no competing interest.View Full Text

molecular biology↗