Starvation yields a drastic decrease in outer-membrane permeability to a periplasmic foreign protein in Myxococcus...

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Physiology

Background:

• Myxococcus xanthus is a model organism for studying bacterial development.
• Recombinant strains can be engineered to study protein production and secretion.
• Previously, AppA protein was shown to be secreted into the medium by vegetative M. xanthus cells.

Purpose of the Study:

• To investigate the secretion of periplasmic proteins in M. xanthus during starvation-induced development.
• To determine if starvation conditions affect protein secretion pathways.
• To compare protein secretion in vegetative versus developing cells.

Main Methods:

• Construction of a recombinant M. xanthus strain producing E. coli beta-galactosidase and AppA protein.
• Culturing M. xanthus under vegetative and starvation conditions.
• Monitoring AppA protein accumulation in the periplasm and release into the medium over time.

Main Results:

• Periplasmic AppA protein release into the medium was significantly reduced during 20 hours of starvation-induced development.
• This lack of secretion was attributed to starvation itself, not the arrest of foreign protein synthesis.
• The ability of cells to undergo development was not required for the observed lack of secretion.

Conclusions:

• Starvation conditions alter protein secretion pathways in M. xanthus.
• Protein secretion during early starvation-induced development may differ from vegetative secretion.
• This suggests distinct mechanisms for protein export under different cellular conditions.