title: Sequence periodicity of Escherichia coli is concentrated in intergenic regions.
abstract: BACKGROUND
  Sequence periodicity with a period close to the DNA helical repeat is a very basic genomic property. This genomic feature was demonstrated for many prokaryotic genomes. The Escherichia coli sequences display the period close to 11 base pairs.
  
  
  RESULTS
  Here we demonstrate that practically only ApA/TpT dinucleotides contribute to overall dinucleotide periodicity in Escherichia coli. The noncoding sequences reveal this periodicity much more prominently compared to protein-coding sequences. The sequence periodicity of ApC/GpT, ApT and GpC dinucleotides along the Escherichia coli K-12 is found to be located as well mainly within the intergenic regions.
  
  
  CONCLUSIONS
  The observed concentration of the dinucleotide sequence periodicity in the intergenic regions of E. coli suggests that the periodicity is a typical property of prokaryotic intergenic regions. We suppose that this preferential distribution of dinucleotide periodicity serves many biological functions; first of all, the regulation of transcription.
authors.affiliation: Genome Diversity Center, Institute of Evolution, University of Haifa, Mt, Carmel 31905 Israel. hosid@research.haifa.ac.il
authors.forename: Sergey
authors.initials: S
authors.lastname: Hosid
authors.forename: Edward N
authors.initials: EN
authors.lastname: Trifonov
authors.forename: Alexander
authors.initials: A
authors.lastname: Bolshoy
mesh_terms: D001482:Base Composition / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D021901:DNA, Intergenic / Q000235:genetics*; D048168:Escherichia coli K12 / Q000235:genetics*; D005583:Fourier Analysis; D016680:Genome, Bacterial; D010507:Periodicity
chemical_list: D004269:DNA, Bacterial; D021901:DNA, Intergenic