The gene ygdP, associated with the invasiveness of Escherichia coli K1, designates a nudix hydrolase, Orf176, active on adenosine (5 ')-pentaphospho-(5 ')-adenosine (Ap(5)A)

ygdP, a gene associated with the invasion of brain microvascular endothelia l cells by Escherichia coli K1 (Badger, J. L., Wass, C. A., and Him, K. S. (2000) Mol. Microbiol. 36,174-182), the primary Gram-negative bacterium cau sing meningitis in newborns, has been cloned and expressed in E. coli. The protein, YgdP, was purified to near homogeneity and identified as a member of the Nudix hydrolase subfamily of dinucleoside oligophosphate pyrophospha tases. It catalyzes the hydrolysis of diadenosine tetra-, penta-, and hexa- phosphates with a preference for diadenosine penta-phosphate, from which it forms ATP and ADP. The enzyme has a requirement for a divalent metal catio n that can be met with Mg2+, Zn2+, or Mn2+ and, like most of the Nudix hydr olases, has an alkaline pH optimum between 8.5 and 9. This is the second id entification of a gene associated with the invasiveness of a human pathogen as a member of the Nudix hydrolase subfamily of dinucleoside oligophosphat e pyrophosphatases, and an examination of homologous proteins in other inva sive bacteria suggests that this may be a common feature of cellular invasi on.