title: The consequences of base pair composition biases for regulatory network organization in prokaryotes.
abstract: Given the dramatic variation in guanine-cytosine (GC) content observed in prokaryotes, from approximately 20% to approximately 75% GC, one wonders if these extreme biases in base pair composition affect the evolution of transcription factor-binding sites (BS). This letter shows that, along the wide range of GC content variation in bacteria, bacterial BS keep a high frequency of AT bases, roughly independently of the background (BG) base pair composition of intergenic regions. As a result, the equilibrium base pair frequencies of BS depart the most from those of BS DNA in GC-rich genomes. This not only implies a higher specificity but also a higher coding barrier for BS in GC-rich genomes. In accordance, we observe that the average percentage of divergently transcribed regions increases with the GC content of the genome, suggesting the use of a more efficient coding strategy.
authors: Otto X
authors: OX
authors: Cordero
authors: Paulien
authors: P
authors: Hogeweg
mesh_terms: D001482:Base Composition / Q000235:genetics*; D020029:Base Pairing / Q000235:genetics*; D053263:Gene Regulatory Networks; D011387:Prokaryotic Cells / Q000378:metabolism*; D014158:Transcription, Genetic