Bipolar localization of the group II intron Ll.LtrB is maintained in Escherichia coli deficient in nucleoid condensation, chromosome partitioning and DNA replication
| Autor: | Arthur Beauregard, Colin J. Coros, Venkata R. Chalamcharla, Carol Lyn Piazza, Marlene Belfort |
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| Rok vydání: | 2006 |
| Předmět: |
DNA Replication
Retroelements Chromosomal Proteins Non-Histone Molecular Sequence Data Origin Recognition Complex Biology medicine.disease_cause Microbiology MreB SeqA protein domain Bacterial Proteins Chromosome Segregation medicine Escherichia coli Nucleoid Molecular Biology Genetics Mutation Base Sequence Escherichia coli Proteins DNA replication Intron RNA-Directed DNA Polymerase Group II intron Chromosomes Bacterial Cell Nucleus Structures Introns DNA-Binding Proteins DNA Transposable Elements Origin recognition complex Molecular Chaperones |
| Zdroj: | Molecular microbiology. 62(3) |
| ISSN: | 0950-382X |
| Popis: | Group II introns are mobile genetic elements that invade their cognate intron-minus alleles via an RNA intermediate, in a process known as retrohoming. They can also retrotranspose to ectopic sites at low frequency. In Escherichia coli, retrotransposition of the lactococcal group II intron, Ll.LtrB, occurs preferentially within the Ori and Ter macrodomains of the E. coli chromosome. These macrodomains migrate towards the poles of the cell, where the intron-encoded protein, LtrA, localizes. Here we investigate whether alteration of nucleoid condensation, chromosome partitioning and replication affect retrotransposition frequencies, as well as bipolar localization of the Ll.LtrB intron integration and LtrA distribution in E. coli. We thus examined these properties in the absence of the nucleoid-associated proteins H-NS, StpA and MukB, in variants of partitioning functions including the centromere-like sequence migS and the actin homologue MreB, as well as in the replication mutants DeltaoriC, seqA, tus and topoIV (ts). Although there were some dramatic fluctuations in retrotransposition levels in these hosts, bipolar localization of integration events was maintained. LtrA was consistently found in nucleoid-free regions, with its localization to the cellular poles being largely preserved in these hosts. Together, these results suggest that bipolar localization of group II intron retrotransposition results from the residence of the intron-encoded protein at the poles of the cell. |
| Databáze: | OpenAIRE |
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