Four-way Junctions in Antisense RNA-mRNA Complexes Involved in Plasmid Replication Control: A Common Theme?

2001 ◽  
Vol 309 (3) ◽  
pp. 605-614 ◽  
Author(s):  
Fabrice A. Kolb ◽  
Eric Westhof ◽  
Bernard Ehresmann ◽  
Chantal Ehresmann ◽  
E.Gerhart H. Wagner ◽  
...  
1988 ◽  
Vol 7 (5-6) ◽  
pp. 559-564
Author(s):  
E. G. H. Wagner ◽  
C. Persson ◽  
M. Öhman ◽  
K. Nordstrom

Plasmid ◽  
2005 ◽  
Vol 54 (3) ◽  
pp. 259-277 ◽  
Author(s):  
Javier Izquierdo ◽  
Tatiana Venkova-Canova ◽  
Miguel A. Ramírez-Romero ◽  
Juan Téllez-Sosa ◽  
Ismael Hernández-Lucas ◽  
...  

2010 ◽  
Vol 192 (13) ◽  
pp. 3268-3278 ◽  
Author(s):  
Ramón Cervantes-Rivera ◽  
Cristina Romero-López ◽  
Alfredo Berzal-Herranz ◽  
Miguel A. Cevallos

ABSTRACT Replication and segregation of the Rhizobium etli symbiotic plasmid (pRetCFN42d) depend on the presence of a repABC operon, which carries all the plasmid-encoded elements required for these functions. All repABC operons share three protein-encoding genes (repA, repB, and repC), an antisense RNA (ctRNA) coding gene, and at least one centromere-like region (parS). The products of repA and repB, in conjunction with the parS region, make up the segregation system, and they negatively regulate operon transcription. The last gene of the operon, repC, encodes the initiator protein. The ctRNA is a negative posttranscriptional regulator of repC. In this work, we analyzed the secondary structures of the ctRNA and its target and mapped the motifs involved in the complex formed between them. Essential residues for the effective interaction localize at the unpaired 5′ end of the antisense molecule and the loop of the target mRNA. In light of our results, we propose a model explaining the mechanism of action of this ctRNA in the regulation of plasmid replication in R. etli.


Plasmid ◽  
2015 ◽  
Vol 78 ◽  
pp. 48-58 ◽  
Author(s):  
América Rivera-Urbalejo ◽  
Ángeles Pérez-Oseguera ◽  
Ofelia E. Carreón-Rodríguez ◽  
Miguel A. Cevallos

1998 ◽  
Vol 62 (2) ◽  
pp. 434-464 ◽  
Author(s):  
Gloria del Solar ◽  
Rafael Giraldo ◽  
María Jesús Ruiz-Echevarría ◽  
Manuel Espinosa ◽  
Ramón Díaz-Orejas

SUMMARY An essential feature of bacterial plasmids is their ability to replicate as autonomous genetic elements in a controlled way within the host. Therefore, they can be used to explore the mechanisms involved in DNA replication and to analyze the different strategies that couple DNA replication to other critical events in the cell cycle. In this review, we focus on replication and its control in circular plasmids. Plasmid replication can be conveniently divided into three stages: initiation, elongation, and termination. The inability of DNA polymerases to initiate de novo replication makes necessary the independent generation of a primer. This is solved, in circular plasmids, by two main strategies: (i) opening of the strands followed by RNA priming (theta and strand displacement replication) or (ii) cleavage of one of the DNA strands to generate a 3′-OH end (rolling-circle replication). Initiation is catalyzed most frequently by one or a few plasmid-encoded initiation proteins that recognize plasmid-specific DNA sequences and determine the point from which replication starts (the origin of replication). In some cases, these proteins also participate directly in the generation of the primer. These initiators can also play the role of pilot proteins that guide the assembly of the host replisome at the plasmid origin. Elongation of plasmid replication is carried out basically by DNA polymerase III holoenzyme (and, in some cases, by DNA polymerase I at an early stage), with the participation of other host proteins that form the replisome. Termination of replication has specific requirements and implications for reinitiation, studies of which have started. The initiation stage plays an additional role: it is the stage at which mechanisms controlling replication operate. The objective of this control is to maintain a fixed concentration of plasmid molecules in a growing bacterial population (duplication of the plasmid pool paced with duplication of the bacterial population). The molecules involved directly in this control can be (i) RNA (antisense RNA), (ii) DNA sequences (iterons), or (iii) antisense RNA and proteins acting in concert. The control elements maintain an average frequency of one plasmid replication per plasmid copy per cell cycle and can “sense” and correct deviations from this average. Most of the current knowledge on plasmid replication and its control is based on the results of analyses performed with pure cultures under steady-state growth conditions. This knowledge sets important parameters needed to understand the maintenance of these genetic elements in mixed populations and under environmental conditions.


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