Trigger factor depletion or overproduction causes defective cell division but does not block protein export

Area of Science:

• Microbiology
• Molecular Biology
• Cell Biology

Background:

• Trigger factor is a cytosolic protein in Escherichia coli.
• It stabilizes proOmpA for translocation across inner membranes in vitro.
• Its precise physiological role in vivo remains to be fully elucidated.

Purpose of the Study:

• To investigate the in vivo function of trigger factor in Escherichia coli.
• To determine the effect of trigger factor levels on protein secretion and cell division.
• To understand the physiological consequences of trigger factor depletion or overproduction.

Main Methods:

• Isolation and sequencing of the trigger factor gene.
• Construction of Escherichia coli strains with regulated trigger factor expression.
• Analysis of proOmpA synthesis and secretion rates in depleted cells.
• Observation of cell morphology in trigger factor-depleted and overproducing strains.
• Genetic analysis using multicopy plasmids, including ftsZ.

Main Results:

• No defect in in vivo proOmpA synthesis or secretion was observed in trigger factor-depleted cells.
• Trigger factor depletion or overproduction resulted in an enrichment of filamented cells.
• Filamentation in trigger factor-overproducing cells was suppressed by expressing the ftsZ gene.

Conclusions:

• Trigger factor is not essential for proOmpA secretion in vivo.
• Trigger factor plays a significant role in Escherichia coli cell division.
• The ftsZ gene, essential for cell division, can suppress trigger factor-related filamentation.