Characteristics of Chi distribution on different bacterial genomes

• Published in: Research in microbiology Vol. 150; no. 9; pp. 579 - 587
• Main Authors: El Karoui, Meriem, Biaudet, Véronique, Schbath, Sophie, Gruss, Alexandra
• Format: Journal Article
• Language: English
• Published: France Elsevier SAS 01-11-1999; Elsevier
• Subjects: Bacillus subtilis - genetics; Bacteria - enzymology; Bacteria - genetics; Base Sequence; Chi; DNA helicase; DNA Helicases - genetics; DNA, Bacterial - genetics; Escherichia coli; Escherichia coli - genetics; Exodeoxyribonuclease V; Exodeoxyribonucleases - genetics; Exonuclease; genome analysis; Genome, Bacterial; Haemophilus influenzae - genetics; helicase; Lactococcus lactis - genetics; Life Sciences; Microbiology and Parasitology; Molecular Sequence Data; oligomer; oligonucleotides; RecBCD; recombination; Recombination, Genetic - genetics; Sequence Analysis; recombination; Chi; exonuclease; genome analysis; oligomer; RecBCD; helicase
• ISSN: 0923-2508; 1769-7123; 0923-2508
• DOI: 10.1016/S0923-2508(99)00132-1

The availability of full genome sequences provides the bases for analyzing global properties of the genetic text. For example, oligonucleotide sequences that are over- or underrepresented can be identified by taking into account the overall genome composition and organization. One of the most overrepresented oligonucleotides in
Escherichia coli is the Chi site, an octanucleotide that stimulates DNA repair by homologous recombination. Here we analyze the genomic distribution of Chi in
E. coli and in the three other bacteria where a Chi sequence has been identified; note that Chi is a different sequence in each organism. For each bacterial genome, Chi sequences are frequent, regularly distributed, and overrepresented. This suggests that selection for Chi may have occurred during evolution to favor efficient repair of a damaged chromosome. Other characteristics of Chi distribution are not conserved and might reflect specific features of DNA repair in each host. The different sequence and characteristics of Chi in each microorganism suggest that selection for Chi occurred independently in different bacteria.