MassIVE MSV000090153 - Changes in the spore proteome of Bacillus cereus in response to introduction of plasmids.

Fluorescent fusion proteins were expressed in Bacillus cereus to visualize the germino-some by introducing a plasmid that carries fluorescent fusion proteins of germinant receptor GerR subunits or germinosome scaffold protein GerD. The effects of plasmid insertion and re-combinant protein expression on the spore proteome were investigated. Proteomic analysis showed that overexpression of the target proteins had negligible effects on the spore proteome. However, plasmid-bearing spores displayed dramatic abundance changes of spore proteins in-volved in signaling and metabolism. Our findings indicate that introduction of a plasmid alone alters spore protein composition dramatically, with 993 proteins significantly down-regulated and 415 proteins significantly up-regulated among 3323 identified proteins. This shows that empty vector controls are more appropriate to compare proteome changes due to plasmid en-coded genes than is the wild-type strain, when using plasmid based genetic tools. Therefore, re-searchers should keep in mind that molecular cloning techniques can alter more than their in-tended targets in a biological system, and interpret results with this in mind.