Cellular dynamics of tRNAs and their genes

Abstract

Edited by Manuel SantosKeywords: tRNA transcription tRNA processing tRNA modification Nucleolus tRNA nuclear export tRNA retrograde movement tRNA turnover a b s t r a c t This discussion focuses on the cellular dynamics of tRNA transcription, processing, and turnover. Early tRNA biosynthesis steps are shared among most tRNAs, while later ones are often individualized for specific tRNAs. In yeast, tRNA transcription and early processing occur coordinately in the nucleolus, requiring topological arrangement of 300 tRNA genes and early processing enzymes to this site; later processing events occur in the nucleoplasm or cytoplasm. tRNA nuclear export requires multiple exporters which function in parallel and the export process is coupled with other cellular events. Nuclear-cytoplasmic tRNA subcellular movement is not unidirectional as a retrograde pathway delivers mature cytoplasmic tRNAs to the nucleus. Despite the long half-lives, there are multiple pathways to turnover damaged tRNAs or normal tRNAs upon cellular stress.

The zipcode-binding protein ZBP1 influences the subcellular location of the Ro 60-kDa autoantigen and the noncoding Y3 RNA

“…Our result that Ro accumulates in nuclei in the presence of leptomycin B does not rule out this possibility, since some Ro remains cytoplasmic when CRM1 is inhibited. Similarly, studies showing that injection of excess hY3 or hY4 RNAs blocks hY1 export, which were interpreted as demonstrating that these RNAs all utilize the same export pathway (Rutjes et al 2001), could indicate that like tRNAs (Hopper et al 2010), Y RNAs can be exported through multiple pathways. Consistent with multiple export pathways, tRNA met i also competes with hY1 for export (Simons et al 1996).…”

Transfer RNA Post-Transcriptional Processing, Turnover, and Subcellular Dynamics in the YeastSaccharomyces cerevisiae

“…Although this review focuses on the studies from yeast, for perspective and where information is available, similarities and differences of the processes in budding yeast to those in other organisms are described. Many of the subjects considered here have been the subjects of other recent reviews (Hopper and Shaheen 2008;Hopper et al 2010;Phizicky and Alfonzo 2010;Phizicky and Hopper 2010;Rubio and Hopper 2011;Maraia and Lamichhane 2011;Parker 2012). Therefore, this article emphasizes the use of genetic and genomic analyses in yeast that led to the discoveries and provides information on new discoveries not previously reviewed.…”

“…There is a rich history of research, in both yeast and vertebrate cells, exploring the mechanism(s) to export nuclear-encoded tRNAs to the cytoplasm (reviewed in Gorlich and Kutay 1999;Simos and Hurt 1999;Grosshans et al 2000b;Yoshihisa 2006;Hopper and Shaheen 2008;Hopper et al 2010;Phizicky and Hopper 2010;Rubio and Hopper 2011;Lee et al 2011). Moreover, the studies have generated numerous unanticipated discoveries.…”

Comparative overview of RNA polymerase II and III transcription cycles, with focus on RNA polymerase III termination and reinitiation

“…3). We note that physical clustering of tRNA genes 107 would tend to increase the local concentration of RNAP III. New approaches that address these important issues and their relevance to the production of tRNAs and 5S rRNA in vivo are needed.…”