Pre-40S ribosome biogenesis factor Tsr1 is an inactive structural mimic of translational GTPases

Urszula M McCaughan, Uma Jayachandran, Vadim Shchepachev, Zhuo Angel Chen, Juri Rappsilber, David Tollervey, Atlanta G Cook

Research output: Contribution to journalArticlepeer-review

Abstract

Budding yeast Tsr1 is a ribosome biogenesis factor with sequence similarity to GTPases, which is essential for cytoplasmic steps in 40S subunit maturation. Here we present the crystal structure of Tsr1 at 3.6 Å. Tsr1 has a similar domain architecture to translational GTPases such as EF-Tu and the selenocysteine incorporation factor SelB. However, active site residues required for GTP binding and hydrolysis are absent, explaining the lack of enzymatic activity in previous analyses. Modelling of Tsr1 into cryo-electron microscopy maps of pre-40S particles shows that a highly acidic surface of Tsr1 is presented on the outside of pre-40S particles, potentially preventing premature binding to 60S subunits. Late pre-40S maturation also requires the GTPase eIF5B and the ATPase Rio1. The location of Tsr1 is predicted to block binding by both factors, strongly indicating that removal of Tsr1 is an essential step during cytoplasmic maturation of 40S ribosomal subunits.

Original languageEnglish
Article number11789
Number of pages8
JournalNature Communications
Volume7
DOIs
Publication statusPublished - 2 Jun 2016

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