Cloning and Sequencing of the Klebsiella pneumoniae O5 wb Gene Cluster and Its Role in Pathogenesis

Abstract

One representative recombinant clone encoding Klebsiella pneumoniae O5-antigen lipopolysaccharide (LPS) was found upon screening for serum resistance in a cosmid-based genomic library of K. pneumoniae KT769 (O5:K57) introduced into Escherichia coli DH5α. A total of eight open reading frames ( wb _O5 gene cluster) were necessary to produce K. pneumoniae O5-antigen LPS in E. coli K-12. The enzymatic activities proposed for the wb _O5 gene cluster are in agreement with the activities proposed for the biosynthesis of K. pneumoniae O5-antigen LPS. Using the complete DNA sequence of the K. pneumoniae wb _O5 gene cluster, we obtained (by single or double recombination) genetically well-characterized mutants devoid only of this O5-antigen LPS. Finally, using these O5 ⁻ mutants and the corresponding wild-type strains or complemented mutants with the wb _O5 gene cluster (O5 ⁺ strains), we found that the presence of K. pneumoniae O5-antigen LPS is essential for some pathogenic features like serum resistance, adhesion to uroepithelial cells, and colonization (experimental infections) of the urinary tract in rats.