Ghalei H, Trepreau J, Collins JC, Bhaskaran H, Strunk BS, Karbstein K. The ATPase Fap7 Tests the Ability to Carry Out Translocation-like Conformational Changes and Releases Dim1 during 40S Ribosome Maturation.
Mol Cell 2017;
67:990-1000.e3. [PMID:
28890337 PMCID:
PMC6192259 DOI:
10.1016/j.molcel.2017.08.007]
[Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 07/08/2017] [Accepted: 08/11/2017] [Indexed: 01/18/2023]
Abstract
Late in their maturation, nascent small (40S) ribosomal subunits bind 60S subunits to produce 80S-like ribosomes. Because of the analogy of this translation-like cycle to actual translation, and because 80S-like ribosomes do not produce any protein, it has been suggested that this represents a quality control mechanism for subunit functionality. Here we use genetic and biochemical experiments to show that the essential ATPase Fap7 promotes formation of the rotated state, a key intermediate in translocation, thereby releasing the essential assembly factor Dim1 from pre-40S subunits. Bypassing this quality control step produces defects in reading frame maintenance. These results show how progress in the maturation cascade is linked to a test for a key functionality of 40S ribosomes: their ability to translocate the mRNA⋅tRNA pair. Furthermore, our data demonstrate for the first time that the translation-like cycle is a quality control mechanism that ensures the fidelity of the cellular ribosome pool.
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