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Category: Microbial Genetics and Molecular Biology
Intracellular Locations of RNA-Modifying Enzymes, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555818296/9781555811334_Chap24-1.gif /docserver/preview/fulltext/10.1128/9781555818296/9781555811334_Chap24-2.gifAbstract:
This chapter talks about the subcellular locations in which the modifications to eukaryotic RNA occur, and focuses mainly on tRNA and rRNA. Most tRNA molecules are built to a common general design, giving rise to the well-known cloverleaf secondary structure and "inverted L" tertiary structure. Availability of the genes and the means of manipulating their expression is of great importance, as stressed for several examples in the chapter, including PUS1 in the section on cytoplasmic tRNA, TRM1 and MODS in the section on mitochondrial tRNA and DIM1 in the section on cytoplasmic rRNA. Although the chapter has concentrated on eukaryotes, in which the questions of intracellular locations and organization are fairly obvious, it should not be excluded that some level of intracellular organization of RNA-modifying enzymes could also occur in prokaryotes, for example by multienzyme interactions between RNA-modifying enzymes and other enzymes of RNA function, such as aminoacyl-tRNA synthases.
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Sequential modifications to yeast tRNATyr precursors in Xenopus oocytes. Modifications which occur on the 104-nt precursor, the 92-nt precursor, and the 78-nt mature tRNA are indicated. Reprinted from Nishikura and De Robertis (1981) with permission.
Sequential modifications to yeast tRNATyr precursors in Xenopus oocytes. Modifications which occur on the 104-nt precursor, the 92-nt precursor, and the 78-nt mature tRNA are indicated. Reprinted from Nishikura and De Robertis (1981) with permission.
Classification of enzymes catalyzing tRNA modifications into two groups according to their sensitivities to the tRNA architecture. Enzymes of class I recognize fragments of tRNA structure, whereas enzymes of class II require the major features of the tRNA architecture to be intact. Reprinted from Grosjean et al. (1996b) with permission; see that reference for further details.
Classification of enzymes catalyzing tRNA modifications into two groups according to their sensitivities to the tRNA architecture. Enzymes of class I recognize fragments of tRNA structure, whereas enzymes of class II require the major features of the tRNA architecture to be intact. Reprinted from Grosjean et al. (1996b) with permission; see that reference for further details.
Schematic representation of translation start sites (in-frame ATG codons) and transcription start sites (starts of wavy lines) in the yeast genes TRM1 (A), MODS (B), and CCA1 (C). Reproduced from Martin and Hopper (1994) with permission.
Schematic representation of translation start sites (in-frame ATG codons) and transcription start sites (starts of wavy lines) in the yeast genes TRM1 (A), MODS (B), and CCA1 (C). Reproduced from Martin and Hopper (1994) with permission.
Frequently modified sites in tRNA a
Frequently modified sites in tRNA a
Positive or negative intron dependence and intron insensitivity to modified nucleoside formation in eukaryotic tRNAs a
Positive or negative intron dependence and intron insensitivity to modified nucleoside formation in eukaryotic tRNAs a
Known tRNA-modifying enzymes with dual specificities for cytoplasmic and mitochondrial tRNAs
Known tRNA-modifying enzymes with dual specificities for cytoplasmic and mitochondrial tRNAs
Numbers of modified nucleosides in representative rRNAs a
Numbers of modified nucleosides in representative rRNAs a
Base-modified nucleosides in eukaryotic rRNA a
Base-modified nucleosides in eukaryotic rRNA a