scholarly journals Analysis of the Roles of the Arabidopsis nMAT2 and PMH2 Proteins Provided with New Insights into the Regulation of Group II Intron Splicing in Land-Plant Mitochondria

2017 ◽  
Vol 18 (11) ◽  
pp. 2428 ◽  
Author(s):  
Michal Zmudjak ◽  
Sofia Shevtsov ◽  
Laure Sultan ◽  
Ido Keren ◽  
Oren Ostersetzer-Biran
Keyword(s):  
Plant Mitochondria ◽  
Group Ii Intron ◽  
Land Plant ◽  
Intron Splicing ◽  
Group Ii

scholarly journals Group II intron splicing factors in plant mitochondria

2014 ◽  
Vol 5 ◽  
Author(s):  
Gregory G. Brown ◽  
Catherine Colas des Francs-Small ◽  
Oren Ostersetzer-Biran
Keyword(s):  
Plant Mitochondria ◽  
Group Ii Intron ◽  
Splicing Factors ◽  
Intron Splicing ◽  
Group Ii

scholarly journals Nuclear Encoded RNA Splicing Factors in Plant Mitochondria

2009 ◽  
Author(s):  
Oren Ostersetzer-Biran ◽  
Alice Barkan
Keyword(s):  
Rna Splicing ◽  
Plant Mitochondria ◽  
Group Ii Intron ◽  
Nuclear Genes ◽  
Metabolic Energy ◽  
Splicing Factors ◽  
Group Ii Introns ◽  
Intron Splicing ◽  
Group Ii ◽  
Mitochondrial Introns

Mitochondria are the site of respiration and numerous other metabolic processes required for plant growth and development. Increased demands for metabolic energy are observed during different stages in the plants life cycle, but are particularly ample during germination and reproductive organ development. These activities are dependent upon the tight regulation of the expression and accumulation of various organellar proteins. Plant mitochondria contain their own genomes (mtDNA), which encode for a small number of genes required in organellar genome expression and respiration. Yet, the vast majority of the organellar proteins are encoded by nuclear genes, thus necessitating complex mechanisms to coordinate the expression and accumulation of proteins encoded by the two remote genomes. Many organellar genes are interrupted by intervening sequences (introns), which are removed from the primary presequences via splicing. According to conserved features of their sequences these introns are all classified as “group-II”. Their splicing is necessary for organellar activity and is dependent upon nuclear-encoded RNA-binding cofactors. However, to-date, only a tiny fraction of the proteins expected to be involved in these activities have been identified. Accordingly, this project aimed to identify nuclear-encoded proteins required for mitochondrial RNA splicing in plants, and to analyze their specific roles in the splicing of group-II intron RNAs. In non-plant systems, group-II intron splicing is mediated by proteins encoded within the introns themselves, known as maturases, which act specifically in the splicing of the introns in which they are encoded. Only one mitochondrial intron in plants has retained its maturaseORF (matR), but its roles in organellar intron splicing are unknown. Clues to other proteins required for organellar intron splicing are scarce, but these are likely encoded in the nucleus as there are no other obvious candidates among the remaining ORFs within the mtDNA. Through genetic screens in maize, the Barkan lab identified numerous nuclear genes that are required for the splicing of many of the introns within the plastid genome. Several of these genes are related to one another (i.e. crs1, caf1, caf2, and cfm2) in that they share a previously uncharacterized domain of archaeal origin, the CRM domain. The Arabidopsis genome contains 16 CRM-related genes, which contain between one and four repeats of the domain. Several of these are predicted to the mitochondria and are thus postulated to act in the splicing of group-II introns in the organelle(s) to which they are localized. In addition, plant genomes also harbor several genes that are closely related to group-II intron-encoded maturases (nMats), which exist in the nucleus as 'self-standing' ORFs, out of the context of their cognate "host" group-II introns and are predicted to reside within the mitochondria. The similarity with known group-II intron splicing factors identified in other systems and their predicted localization to mitochondria in plants suggest that nuclear-encoded CRM and nMat related proteins may function in the splicing of mitochondrial-encoded introns. In this proposal we proposed to (i) establish the intracellular locations of several CRM and nMat proteins; (ii) to test whether mutations in their genes impairs the splicing of mitochondrial introns; and to (iii) determine whether these proteins are bound to the mitochondrial introns in vivo.  

scholarly journals A functional twintron, ‘zombie’ twintrons and a hypermobile group II intron invading itself in plant mitochondria

2020 ◽  
Vol 48 (5) ◽  
pp. 2661-2675 ◽  
Author(s):  
Simon Zumkeller ◽  
Philipp Gerke ◽  
Volker Knoop
Keyword(s):  
Plant Mitochondria ◽  
Group Ii Intron ◽  
Land Plant ◽  
Plant Evolution ◽  
Mitochondrial Genomes ◽  
Group I ◽  
Present Distribution ◽  
Group Ii ◽  
Gains And Losses ◽  
Internal Group

Abstract The occurrence of group II introns in plant mitochondrial genomes is strikingly different between the six major land plant clades, contrasting their highly conserved counterparts in chloroplast DNA. Their present distribution likely reflects numerous ancient intron gains and losses during early plant evolution before the emergence of seed plants. As a novelty for plant organelles, we here report on five cases of twintrons, introns-within-introns, in the mitogenomes of lycophytes and hornworts. An internal group II intron interrupts an intron-borne maturase of an atp9 intron in Lycopodiaceae, whose splicing precedes splicing of the external intron. An invasive, hypermobile group II intron in cox1, has conquered nine further locations including a previously overlooked sdh3 intron and, most surprisingly, also itself. In those cases, splicing of the external introns does not depend on splicing of the internal introns. Similar cases are identified in the mtDNAs of hornworts. Although disrupting a group I intron-encoded protein in one case, we could not detect splicing of the internal group II intron in this ‘mixed’ group I/II twintron. We suggest the name ‘zombie’ twintrons (half-dead, half-alive) for such cases where splicing of external introns does not depend any more on prior splicing of fossilized internal introns.

scholarly journals Group II intron as cold sensor for self-preservation and bacterial conjugation

2020 ◽  
Vol 48 (11) ◽  
pp. 6198-6209 ◽  
Author(s):  
Xiaolong Dong ◽  
Guosheng Qu ◽  
Carol Lyn Piazza ◽  
Marlene Belfort
Keyword(s):  
Group Ii Intron ◽  
Cold Sensitivity ◽  
Group Ii Introns ◽  
Intron Splicing ◽  
Kinetic Trap ◽  
Group Ii ◽  
Self Splicing ◽  
Mrna Targeting ◽  
Cold Sensor

Abstract Group II introns are self-splicing ribozymes and mobile genetic elements. Splicing is required for both expression of the interrupted host gene and intron retromobility. For the pRS01 plasmid-encoded Lactococcus lactis group II intron, Ll.LtrB, splicing enables expression of the intron's host relaxase protein. Relaxase, in turn, initiates horizontal transfer of the conjugative pRS01 plasmid and stimulates retrotransposition of the intron. Little is known about how splicing of bacterial group II introns is influenced by environmental conditions. Here, we show that low temperatures can inhibit Ll.LtrB intron splicing. Whereas autocatalysis is abolished in the cold, splicing is partially restored by the intron-encoded protein (IEP). Structure profiling reveals cold-induced disruptions of key tertiary interactions, suggesting that a kinetic trap prevents the intron RNA from assuming its native state. Interestingly, while reduced levels of transcription and splicing lead to a paucity of excised intron in the cold, levels of relaxase mRNA are maintained, partially due to diminished intron-mediated mRNA targeting, allowing intron spread by conjugal transfer. Taken together, this study demonstrates not only the intrinsic cold sensitivity of group II intron splicing and the role of the IEP for cold-stress adaptation, but also maintenance of horizontal plasmid and intron transfer under cold-shock.

scholarly journals Mechanism of maturase-promoted group II intron splicing

2001 ◽  
Vol 20 (24) ◽  
pp. 7259-7270 ◽  
Author(s):  
M. Matsuura
Keyword(s):  
Group Ii Intron ◽  
Intron Splicing ◽  
Group Ii

scholarly journals A plant-specific RNA-binding domain revealed through analysis of chloroplast group II intron splicing

2009 ◽  
Vol 106 (11) ◽  
pp. 4537-4542 ◽  
Author(s):  
T. S. Kroeger ◽  
K. P. Watkins ◽  
G. Friso ◽  
K. J. van Wijk ◽  
A. Barkan
Keyword(s):  
Rna Binding ◽  
Group Ii Intron ◽  
Binding Domain ◽  
Intron Splicing ◽  
Rna Binding Domain ◽  
Group Ii

scholarly journals CRS1, a Chloroplast Group II Intron Splicing Factor, Promotes Intron Folding through Specific Interactions with Two Intron Domains

2004 ◽  
Vol 17 (1) ◽  
pp. 241-255 ◽  
Author(s):  
Oren Ostersetzer ◽  
Amy M. Cooke ◽  
Kenneth P. Watkins ◽  
Alice Barkan
Keyword(s):  
Group Ii Intron ◽  
Splicing Factor ◽  
Specific Interactions ◽  
Intron Splicing ◽  
Group Ii
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