Differential expression of PE and PE_PGRS genes in Mycobacterium tuberculosis strains.

In this study, the expression of the Mycobacterium tuberculosis PE, PE_polimorphic GC-rich sequences (PGRS) gene family encoding approximately 99 glycine-rich proteins was assayed by reverse-transcriptase polymerase chain reaction (RT-PCR) in M. tuberculosis H37Rv, Mycobacterium canettii and two clinical isolates of M. tuberculosis. Restriction analyses and sequencing of the RT-PCR products showed that all the strains expressed the PE Rv1172c gene while the PE_PGRS Rv3652 gene was only expressed by one of the M. tuberculosis clinical isolates, and the PE_PGRS Rv0578c was not expressed by M. canettii. It was also determined that the PE_PGRS Rv0278c and Rv0279c were not expressed by any of the studied strains. The data presented in this report show that the PE, PE_PGRS genes are differentially expressed in M. tuberculosis strains during in vitro growth. These findings suggest that PE, PE_PGRS genes may play a role in protein variation between M. tuberculosis strains.