Enzymatic capabilities of bacteria associated with apple maggot flies: A postulated role in attraction

Isolates of the bacterium Enterobacter agglomerans, obtained from the alimentary tract of the apple maggot fly, Rhagoletis pomonella, were found to be attractive or nonattractive in attraction tests. Polyacrlyamide gel electrophoresis (PACE) of whole bacterial cell and outer membrane preparations of bacteria revealed the presence of a protein confined to isolates attractive to the flies. This protein, with an approximate molecular weight of 106 kDa, was found to be extracellular in E. agglomerans, but absent in either whole cell or extracellular preparations of Klebsiella oxytoca or Klebsiella pneumoniae. Comparison of this protein with authentic uricase revealed that this protein has a molecular weight, a PAGE migration rate (R-f = 0.22), and behavior on a G-100 Sephadex column similar to pure uricase. This protein appears to be made by E. agglomerans in the absence of uric acid, i.e., constitutively, and its presence is positively linked to apple maggot fly response in attraction assays. The probable roles of this unique protein in purine degradation and the lives of apple maggot adults are discussed.