Title:
Non-canonical structures and functions of the human ribosome: G-quadruplexes and heme appropriation

Thumbnail Image
Author(s)
Mestre Fos, Santiago
Authors
Advisor(s)
Williams, Loren D.
Advisor(s)
Editor(s)
Associated Organization(s)
Organizational Unit
Series
Supplementary to
Abstract
The ribosome is a macromolecular ribonucleoprotein machine that is responsible for the synthesis of all proteins in cells. Mammalian ribosomal RNAs (rRNAs) are nearly twice as large as those of prokaryotes. Differences in rRNA size are due to expansion segments (ESs), which are double-stranded RNA ramifications that protrude from the ribosomal surface. Here we show that numerous human rRNA ESs are capable of forming stable G-quadruplexes (G4s) in vitro and in vivo. G4s are non-canonical nucleic acid secondary structures that are thought to play key regulatory roles in cells. In addition, by taking a chemical biology approach that integrates results from immunofluorescence, G4 ligands, heme affinity reagents, and a genetically encoded fluorescent heme sensor, we report that human ribosomal G4s appropriate heme and regulate its cytosolic bioavailability. Immunofluorescence experiments indicate that the vast majority of extra-nuclear G4s are associated with rRNA. Overall, these results indicate that the RNA G-quadruplexome is ribosome-centric and suggest ribosomes are hubs of heme metabolism.
Sponsor
Date Issued
2020-07-14
Extent
Resource Type
Text
Resource Subtype
Dissertation
Rights Statement
Rights URI