(623g) Induction of Mibrobial Defense Mechanisms

Exposure of two diverse bacterial species to a phosphate analogue triggers the upregulation of proteins involved in protective responses.  In Bacillus a protein with a MW of 28,624 and a pI of 6.6 was found to be upregulated 77 fold as judged by quantitative analysis of 2-D protein gels. This protein corresponds to the recently identified bacteriocin, YbdN, which has a MW of 28,699 and pI of 6.79. While the mechanism by which YbdN kills bacteria is not known, other class III bacteriocins are known to attack the cell wall or disrupt the cell membrane. Another, possibly protective protein induced 48 fold in Bacillus, is the YopN prophage derived protein. This protein may prevent superinfection with another bacteriophage. In E. coli a protein of ~120,000 MW and a pI of 6.08 was upregulated 150 fold. This protein corresponds to the T1R1 restriction enzyme otherwise known as EcoR124II R protein. Restriction enzymes are well known for their role in defending bacteria and archaea from viruses. While other work with the analogue has shown increases in proteins levels via mRNA stabilization, the amount of induction is typically only 5-20 fold.  The occurrence of increases greater than 40 fold suggests the activation of a regulatory switch as a secondary response to the global stabilization of mRNA with analogue. The approach taken may be useful in identifying additonal bacteriocides and defensive proteins in a variety of microbes. The use of the analogue also greatly facilitates the detection of minor proteins on 2D gels.