The Detection of Nucleotide Sequences with Strong Similarity to Hormone Responsive Elements in the Genome of Eubacteria and Archaebacteria and Their Possible Relation to Similar Sequences Present in the Mitochondrial Genome

To account for the presence of nucleotide sequences in mitochondria with similarity to the Hormone Response Elements (HREs) of the nuclear genomes of man, rat and mouse, the genomes of several procaryotes have been screened for the presence of the sequences AGAACA NNN TGTTCT and GGTACA NNN TGTTCT, which represent perfect palindromic and consensus class I HREs, respectively, and for the sequence AGGTCA NNN TGACCT, which represents class II HRE. y of the examined procaryotes, eubacteria and archaebacteria, almost perfect palindromic class I HREs and perfect or almost perfect class II half palindromic HREs have been detected in various genes, some of which encode proteins involves in energy metabolism, in replication and in transcription control. These findings support the hypothesis that the similar sequences found in mitochondria, potentially involved in hormonal regulation of respiratory enzyme biosynthesis, were introduced into eucaryotic cell by the procaryotic endosymbionts.