scholarly journals Manipulating Chloroplast Gene Expression: A Genetic and Mechanistic Analysis of Processes that Control RNA Stability

2004 ◽  
Author(s):  
David Stern ◽  
Gadi Schuster
Keyword(s):  
Gene Expression ◽  
Biochemical Characterization ◽  
Plastid Transformation ◽  
Rna Stability ◽  
Chloroplast Gene Expression ◽  
Endonucleolytic Cleavage ◽  
Mechanistic Analysis ◽  
Novel Traits ◽  
Major Player ◽  
Rna Accumulation

New potential for engineering chloroplasts to express novel traits has stimulated research into relevant techniques and genetic processes, including plastid transformation and gene regulation. This BARD-funded research dealt with the mechanisms that influence chloroplast RNA accumulation, and thus gene expression. Previous work on cpRNA catabolism has elucidated a pathway initiated by endonucleolytic cleavage, followed by polyadenylation and exonucleolytic degradation. A major player in this process is the nucleus-encoded exoribo-nuclease/polymerase polynucleotide phosphorylase (PNPase). Biochemical characterization of PNPase has revealed a modular structure that controls its RNA synthesis and degradation activities, which in turn are responsive to the phosphate (P) concentration. During the funding period, new insights emerged into the molecular mechanism of RNA metabolism in the chloroplast and cyanobacteria, suggesting strategies for improving agriculturally-important plants or plants with novel introduced traits.

Role of small nuclear RNAs in eukaryotic gene expression

2013 ◽  
Vol 54 ◽  
pp. 79-90 ◽  
Author(s):  
Saba Valadkhan ◽  
Lalith S. Gunawardane
Keyword(s):  
Gene Expression ◽  
Protein Interactions ◽  
Rna Stability ◽  
Splice Sites ◽  
Branch Site ◽  
Small Nuclear Rnas ◽  
Eukaryotic Gene Expression ◽  
Eukaryotic Gene ◽  
Rna Biogenesis

Eukaryotic cells contain small, highly abundant, nuclear-localized non-coding RNAs [snRNAs (small nuclear RNAs)] which play important roles in splicing of introns from primary genomic transcripts. Through a combination of RNA–RNA and RNA–protein interactions, two of the snRNPs, U1 and U2, recognize the splice sites and the branch site of introns. A complex remodelling of RNA–RNA and protein-based interactions follows, resulting in the assembly of catalytically competent spliceosomes, in which the snRNAs and their bound proteins play central roles. This process involves formation of extensive base-pairing interactions between U2 and U6, U6 and the 5′ splice site, and U5 and the exonic sequences immediately adjacent to the 5′ and 3′ splice sites. Thus RNA–RNA interactions involving U2, U5 and U6 help position the reacting groups of the first and second steps of splicing. In addition, U6 is also thought to participate in formation of the spliceosomal active site. Furthermore, emerging evidence suggests additional roles for snRNAs in regulation of various aspects of RNA biogenesis, from transcription to polyadenylation and RNA stability. These snRNP-mediated regulatory roles probably serve to ensure the co-ordination of the different processes involved in biogenesis of RNAs and point to the central importance of snRNAs in eukaryotic gene expression.

Transcriptional and posttranscriptional regulation of chloroplast gene expression by heavy metals in barley seedlings

2011 ◽  
Vol 58 (6) ◽  
pp. 1040-1047 ◽  
Author(s):  
N. R. Zaripova ◽  
V. P. Kholodova ◽  
Ya. O. Zubo ◽  
V. V. Kusnetsov ◽  
Vl. V. Kuznetsov
Keyword(s):  
Gene Expression ◽  
Heavy Metals ◽  
Posttranscriptional Regulation ◽  
Chloroplast Gene ◽  
Chloroplast Gene Expression

Photosynthetic control of chloroplast gene expression

Nature ◽  
10.1038/17624 ◽  
1999 ◽  
Vol 397 (6720) ◽  
pp. 625-628 ◽  
Author(s):  
Thomas Pfannschmidt ◽  
Anders Nilsson ◽  
John F. Allen
Keyword(s):  
Gene Expression ◽  
Chloroplast Gene ◽  
Chloroplast Gene Expression ◽  
Photosynthetic Control

scholarly journals Regulation of asparagine synthetase gene expression by amino acid starvation

1991 ◽  
Vol 11 (12) ◽  
pp. 6059-6066
Author(s):  
S S Gong ◽  
L Guerrini ◽  
C Basilico
Keyword(s):  
Gene Expression ◽  
Amino Acid ◽  
Transcription Initiation ◽  
Rna Stability ◽  
Genomic Region ◽  
Amino Acid Starvation ◽  
Asparagine Synthetase ◽  
Temperature Sensitive ◽  
Mrna Levels ◽  
Regulation Of Expression

We have studied the regulation of expression of the asparagine synthetase (AS) gene in ts11 cells, a mutant of BHK hamster cells which encodes a temperature-sensitive AS and therefore does not produce endogenous asparagine at 39.5 degrees C. Incubation of ts11 cells at the nonpermissive temperature drastically increases the level of AS mRNA, and the stimulation of AS mRNA expression is effectively suppressed by the addition of asparagine to the medium. We show here that regulation of AS gene expression involves cis-acting elements which are contained in the mRNA as well as in the 5' genomic region. When a plasmid containing the human AS cDNA under the control of the human AS promoter region was stably transfected into ts11 cells, the expression of human AS RNAs was regulated as that of the endogenous hamster transcripts, indicating that this construct contained all cis elements necessary for regulation. Expression of the AS cDNA in ts11 cells under the control of a constitutive foreign promoter was also regulated by the concentration of asparagine, and this regulation required translation. When we introduced by mutagenesis a number of stop codons in the AS cDNA, the mutant mRNAs with short open reading frames were expressed at low levels that were not increased by asparagine deprivation. Inhibition of protein and RNA synthesis also prevented down-regulation of AS mRNA levels by high concentrations of asparagine. In a parallel series of experiments, we showed that an AS DNA fragment including the promoter and first exon can also regulate RNA expression in response to asparagine concentration. Furthermore, similar increases in the levels of AS RNAs are produced not only by asparagine deprivation in ts11 cells but also by deprivation of human and wild-type BHK cells of leucine, isoleucine, or glutamine. Thus, regulation of AS gene expression is a response to amino acid starvation through mechanisms which appear to involve both changes in RNA stability and change in the rates of transcription initiation or elongation.

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