Distribution of DNA curvature in bacterial genomes
Alexander Bolshoy
Institute of Evolution, University of Haifa
Computer analysis of completely sequenced prokaryotic genomes is
the key to understanding the evolution of gene regulation and will
provide invaluable direction for future experimental biological
research programs in the subject. We analyzed the distribution of
predicted intrinsic curvature along all complete bacterial genomes.
Sequence-dependent DNA curvature is known to play an important role
in transcription initiation of many genes. Our analysis supported
this commonly accepted hypothesis. However, according to their
curvature distribution, the genomes were di-vided into two groups.
Curvature distribution in all bacteria of the first group indicated
a substantial fraction of genes characterized by intrinsic DNA
curvature located within or immediately upstream to adjacent
untranslated regions. We did not find this peculiar DNA curvature
distribution in bacteria of the second group. Remarkably, all
bacteria of the first group are mesophilic, whereas bacteria of the
second group are hyperthermo-philic. It was shown in vitro that
intrinsic DNA curvature disappears with raising temperature. We
hypothesize that the DNA curvature plays a biological role in gene
regulation in mesophilic as against hyperthermophilic prokaryotes,
i.e. DNA curvature presumably has a functional adaptive
significance determined by temperature selection. As more complete
prokaryotic genomes are sequenced, further verification of this
finding will pave the road for the future of Ecological Genomic
Studies. We consider this field to be fundamental in understanding
genome evolution.