This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Santoyo, G.
Right arrow Articles by Romero, D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Santoyo, G.
Right arrow Articles by Romero, D.

 Previous Article  |  Next Article 

Journal of Bacteriology, June 2005, p. 4116-4126, Vol. 187, No. 12
0021-9193/05/$08.00+0     doi:10.1128/JB.187.12.4116-4126.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Gene Conversion Tracts Associated with Crossovers in Rhizobium etli

Gustavo Santoyo, Jaime M. Martínez-Salazar, César Rodríguez, and David Romero*

Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apartado Postal 565-A, Cuernavaca, Morelos, México

Received 8 December 2004/ Accepted 11 March 2005

Gene conversion has been defined as the nonreciprocal transfer of information between homologous sequences. Despite its broad interest for genome evolution, the occurrence of this mechanism in bacteria has been difficult to ascertain due to the possible occurrence of multiple crossover events that would mimic gene conversion. In this work, we employ a novel system, based on cointegrate formation, to isolate gene conversion events associated with crossovers in the nitrogen-fixing bacterium Rhizobium etli. In this system, selection is applied only for cointegrate formation, with gene conversions being detected as unselected events. This minimizes the likelihood of multiple crossovers. To track the extent and architecture of gene conversions, evenly spaced nucleotide changes were made in one of the nitrogenase structural genes (nifH), introducing unique sites for different restriction endonucleases. Our results show that (i) crossover events were almost invariably accompanied by a gene conversion event occurring nearby; (ii) gene conversion events ranged in size from 150 bp to 800 bp; (iii) gene conversion events displayed a strong bias, favoring the preservation of incoming sequences; (iv) even small amounts of sequence divergence had a strong effect on recombination frequency; and (v) the MutS mismatch repair system plays an important role in determining the length of gene conversion segments. A detailed analysis of the architecture of the conversion events suggests that multiple crossovers are an unlikely alternative for their generation. Our results are better explained as the product of true gene conversions occurring under the double-strand break repair model for recombination.

* Corresponding author. Mailing address: Programa de Ingeniería Genómica, Centro de Ciencias Genómicas-Universidad Nacional Autónoma de México. Apartado Postal 565-A, 62210 Cuernavaca, Mor., México. Phone: 52 (777) 3175867. Fax: 52 (777) 3175581. E-mail: dromero{at}ccg.unam.mx.

Journal of Bacteriology, June 2005, p. 4116-4126, Vol. 187, No. 12
0021-9193/05/$08.00+0     doi:10.1128/JB.187.12.4116-4126.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Castellanos, M., Romero, D. (2009). The Extent of Migration of the Holliday Junction Is a Crucial Factor for Gene Conversion in Rhizobium etli. J. Bacteriol. 191: 4987-4995 [Abstract] [Full Text]  
  • Binet, R., Maurelli, A. T. (2009). Transformation and isolation of allelic exchange mutants of Chlamydia psittaci using recombinant DNA introduced by electroporation. Proc. Natl. Acad. Sci. USA 106: 292-297 [Abstract] [Full Text]  
  • Sepulveda, E., Perez-Mendoza, D., Ramirez-Romero, M. A., Soto, M. J., Lopez-Lara, I. M., Geiger, O., Sanjuan, J., Brom, S., Romero, D. (2008). Transcriptional Interference and Repression Modulate the Conjugative Ability of the Symbiotic Plasmid of Rhizobium etli. J. Bacteriol. 190: 4189-4197 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»