The gene locus yijP contributes to Escherichia coli K1 invasion of brain microvascular endothelial cells

Most cases of Escherichia coli meningitis develop as a result of hematogeno us spread, but it is not clear how circulating E. coli crosses the blood-br ain barrier. A TnphoA mutant of E, coli K1 RS218 was shown to be significan tly less invasive than its parent strain in bovine and human brain microvas cular endothelial cells (BMEC), which constitute the blood-brain barrier. M ore importantly, traversal of the blood-brain barrier was significantly les s with this mutant than with the parent strain in newborn rats with experim ental hematogenous meningitis, A DNA segment containing the TnphoA insertio n site was cloned from RS218, and the cloned DNA complemented the TnphoA mu tant in invasion of BMEC, Nucleotide sequence revealed a near identity to t hat of a hypothetical yijP gene (also called f577) in the E, coli K-12 geno me. Sequence analysis indicated that the E. coli K1 yijP gene likely encode s a 66.6-kDa membrane protein. Deletion and complementation experiments ind icated that the yijP gene was involved in E. coli K1 invasion of BMEC, i.e. , the invasive ability of E, coli K1 was significantly reduced after yijP w as deleted and was restored by complementation with a plasmid containing th e yijP open reading frame. This is the first demonstration that the yijP ge ne locus plays a role in the pathogenesis of E. coli K1 meningitis.