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How do Has1, Nop12, and Rrp5 Cooperate in Integrating 40S and 60S Assembly?
Author(s) -
Smith Hans,
Khoshnevis Sohail,
Karbstein Katrin
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.596.3
Subject(s) - ribosome , eukaryotic small ribosomal subunit , protein subunit , microbiology and biotechnology , eukaryotic ribosome , eukaryotic large ribosomal subunit , ribosomal protein , ribosomal rna , biology , chemistry , biochemistry , rna , gene
Ribosomes are present in every cell and are the machinery behind protein synthesis. Proper assembly of ribosomes is essential to the life of all organisms, however the mechanism by which they are assembled and maintained are largely unknown. There are over 200 assembly factors involved in ribosomal subunit formation. Of these, only 3 have been shown to be essential in the maturation of both the 40S and 60S subunits of the ribosome: Has1, Rrp5, and Prp43. During transcription, the 40S subunit is separated from the 60S subunit via cleavage at the A 2 site. Has1 is a DEAD‐box protein whose ATPase activity has been shown to be essential for A 2 cleavage, however the true role it plays has yet to be elucidated. Previous data from the Karbstein lab has shown that Rrp5 and Has1 have strong binding affinities for one another. Mapping out the full protein‐protein interaction network of Has1, or in the Rrp5‐Has1 complex, may prove to be vital in uncovering the roles these proteins have in ribosome maturation. Here we demonstrate that the 60S assembly factor, Nop12, also showed to have a strong affinity for Rrp5, which may have major implications in its role in the coordination of ribosome assembly. Has1's ATPase activity is stimulated equally by different lengths of rRNA segments and, interestingly, it shows cooperative binding when the segments move into the 5.8S region and on. No significant increase in ATPase activity for Has1 was observed when introduced with Rrp5 and Nop12. The data presented here suggest that the Rrp5‐Has1 complex interacts with Nop12 in such a way that causes a conformational shift in the rRNA segment being synthesized, which allows for proper A 2 cleavage. Support or Funding Information NSF REU funding for TSRI's SURF programSchematic of the pre‐rRNA segments being tested with Has1.Model of proposed mechanism of A 2 cleavage with coordination of Has1, Rrp5, and Nop12.