Transcriptional regulation, a multiple-step process, is still poorly understood in the important
pig pathogen Mycoplasma hyopneumoniae. Basic motifs like promoters and terminators
have already been described, but no other cis-regulatory elements have been found. DNA
repeat sequences have been shown to be an interesting potential source of cis-regulatory
elements. In this work, a genome-wide search for tandem and palindromic repetitive elements
was performed in the intergenic regions of all coding sequences from M. hyopneumoniae
strain 7448. Computational analysis demonstrated the presence of 144 tandem
repeats and 1,171 palindromic elements. The DNA repeat sequences were distributed
within the 5′ upstream regions of 86% of transcriptional units of M. hyopneumoniae strain
7448. Comparative analysis between distinct repetitive sequences found in related mycoplasma
genomes demonstrated different percentages of conservation among pathogenic
and nonpathogenic strains. qPCR assays revealed differential expression among genes
showing variable numbers of repetitive elements. In addition, repeats found in 206 genes
already described to be differentially regulated under different culture conditions of M. hyopneumoniae
strain 232 showed almost 80% conservation in relation to M. hyopneumoniae
strain 7448 repeats. Altogether, these findings suggest a potential regulatory role of tandem
and palindromic DNA repeats in the M. hyopneumoniae transcriptional profile.
