Global expression profiling of strains harbouring null mutations reveals that the five rpf-like genes of Mycobacterium tuberculosis show functional redundancy

• Published in: Tuberculosis (Edinburgh, Scotland) Vol. 84; no. 3; pp. 167 - 179
• Main Authors: Downing, K.J., Betts, J.C., Young, D.I., McAdam, R.A., Kelly, F., Young, M., Mizrahi, V.
• Format: Journal Article
• Language: English
• Published: Scotland Elsevier Ltd 2004
• Subjects: Bacterial Proteins - genetics; Cluster Analysis; Colony Count, Microbial; Cytokines - genetics; Dormancy; Gene Deletion; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Humans; Micrococcus luteus; Mycobacterium; Mycobacterium tuberculosis; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - growth & development; Resuscitation; Reverse Transcriptase Polymerase Chain Reaction; Rpf; Tuberculosis; Dormancy; Mycobacterium; Rpf; Tuberculosis; Resuscitation
• ISSN: 1472-9792; 1873-281X
• DOI: 10.1016/j.tube.2003.12.004

Setting: Aged, dormant cultures of
Mycobacterium tuberculosis can be resuscitated by a secreted, proteinaceous growth factor from
Micrococcus luteus, known as resuscitation-promoting factor (Rpf).
M. tuberculosis contains five
rpf-like genes,
rpfA (Rv0867c),
rpfB (Rv1009),
rpfC (Rv1884c),
rpfD (Rv2389c) and
rpfE (Rv2450c), that bear significant similarity to
Mi. luteus rpf, suggesting that these too may play a role in growth and/or reactivation from a quiescent state.
Objective and design: Unmarked deletion mutants of each of the five
rpf-like genes of
M. tuberculosis H37Rv were constructed and their phenotypes and global gene expression profiles were assessed.
Results and conclusions: Deletion of any one of the
rpf-like genes did not affect growth or survival of
M. tuberculosis in liquid culture, but some alterations in colony-forming ability and colonial morphology were observed. Global gene expression profiling suggested that loss of
rpfC affected the expression of the largest number of genes and there was a significant overlap in the differential gene expression profile of the
rpfC mutant with those of the
rpfB, rpfD and
rpfE mutants. The expression profile of the
rpfA mutant was notably less similar, but inverse associations with genes affected in the other mutants were observed. These results, together with those obtained by real-time, quantitative RT-PCR, suggest that the
rpf-like genes serve wholly or partially overlapping functions in
M. tuberculosis.