ZapA Protease Expression - Proteus mirabilis

Proteus mirabilis possesses an extracellular IgA-degrading protease, referred to as ZapA, that is one of the most critical components of the virulence mechanism, perhaps the most important P. mirabilis virulence factor. P. mirabilis regulates zapA expression through changes in transcription of the gene, which is activated during swarmer cell differentiation, along with several other virulence proteins. In these studies, we uncovered a unique feature of the zapA regulatory region: 11 copies of a heptad sequence, CAAACAT, in a direct tandem repeat upstream of a possible promoter. The data also indicate that a specific DNA-binding protein expressed in differentiated swarmer cells, but not in vegetative swimmer cells, binds to the zapA promoter region. We are exploring the idea that the heptad repeat region may be a recognition site for the binding of a regulatory protein that controls zapA expression with the goal of understanding how zapA expression is cyclically controlled during swarming biofilm formation.