Morphological features and signature gene response elicited by inactivation of FtsI in Mycobacterium tuberculosis.
OBJECTIVE
Universally conserved events in cell division provide the opportunity for the development of novel chemotherapeutics against Mycobacterium tuberculosis. The aim of this study was to use the beta-lactam antimicrobials cefalexin and piperacillin to inhibit FtsI and characterize the morphological changes and global transcriptional activities of genes to identify a signature response to FtsI inactivation.


METHODS
Cefalexin and piperacillin were used to block cell division, and microscopy was used to evaluate the effects on bacterial morphology and ultrastructure. Global transcriptional analysis was performed to determine the impact of FtsI inhibition on cell cycle processes and to identify molecular markers.


RESULTS
Inhibition of FtsI with cefalexin and piperacillin resulted in filamentous cells with multiple concentric rings and occasional branching as visualized by light and electron microscopy. Whole genome microarray-based transcriptional profiling and transcriptional mapping allowed the evaluation of cell cycle processes in response to inhibition of FtsI and characterization of transcriptional response and cell cycle processes.


CONCLUSIONS
This study substantiated that FtsZ-ring constriction and septal resolution require the transpeptidase activity of FtsI, making FtsI essential for cell division in M. tuberculosis. Therefore, FtsI is a target for drug discovery, and these studies provided a molecular signature of FtsI inactivation that can be applied to screening strategies for novel FtsI inhibitors.
Slayden
Richard A
RA
Department of Microbiology, Mycobacteria Research Laboratories, Colorado State University, Fort Collins, CO 80523, USA. richard.slayden@colostate.edu
Belisle
John T
JT
D001426:Bacterial Proteins / Q000037:antagonists & inhibitors*; D002455:Cell Division / Q000187:drug effects; D002506:Cephalexin / Q000494:pharmacology; D020869:Gene Expression Profiling; D006131:Growth Inhibitors / Q000494:pharmacology*; D008853:Microscopy; D008855:Microscopy, Electron, Scanning; D009169:Mycobacterium tuberculosis / Q000166:cytology* / Q000187:drug effects* / Q000254:growth & development; D020411:Oligonucleotide Array Sequence Analysis; D010878:Piperacillin / Q000494:pharmacology
D001426:Bacterial Proteins; D006131:Growth Inhibitors; D002506:Cephalexin; D010878:Piperacillin