Enterobacterial repetitive intergenic consensus (ERIC) sequences in Escherichia coli: Evolution and implications for...

Area of Science:

• Genomics
• Molecular Biology
• Bacterial Genetics

Background:

• Enterobacterial repetitive intergenic consensus (ERIC) sequences are palindromic elements present in enteric bacteria and vibrios.
• These repetitive elements are utilized in bacterial fingerprinting techniques like ERIC-PCR.

Purpose of the Study:

• To investigate the distribution and conservation of ERIC sequences within the complete genomes of nine Escherichia coli strains.
• To understand the evolutionary dynamics and potential functional significance of ERIC sequences.

Main Methods:

• Comparative genomics analysis of ERIC sequence distribution across nine E. coli (including Shigella) genomes.
• Analysis of ERIC sequence conservation and insertion mechanisms through genome-wide comparisons with Salmonella enterica.

Main Results:

• ERIC sequences show a tendency to be located adjacent to highly expressed genes.
• Significant variation in ERIC element presence exists among strains, yet some copies are conserved across E. coli and S. enterica.
• ERIC sequence insertion involves TA dinucleotide duplication, and specific 70-bp inserts evolve independently.

Conclusions:

• ERIC sequences are surprisingly conserved between E. coli and S. enterica, suggesting a functional role, potentially in mRNA stability.
• The generation of new ERIC copies follows a master copy model involving TA duplication.
• The low abundance of ERIC sequences in E. coli genomes implies ERIC-PCR's effectiveness is not solely dependent on these elements.