Study of the mechanism of gene expression regulation by Fur regulator in Klebsiella pneumoniae: consequences on the expression of virulence factors mediated by quorum-sensing

Abstract

Klebsiella pneumoniae is a Gram-negative pathogenic bacterium which causes a variety of infections, such as pneumonia, meningitis, septicemia, among others. As an opportunistic pathogen, K. pneumoniae preferentially attacks immunocompromised individuals and represents a major cause of hospital-acquired infections. In recent years, it has been observed an increase in antibiotic resistant for some K. pneumoniae clinical strains. In addition, the increasing occurrence of severe infections in healthy individuals emphasizes the necessity of elucidating the mechanism of virulence that determines the pathogenicity of K. pneumoniae. Considering that iron plays an important role on the virulence of pathogenic bacteria, this work aim to identify and characterize genes related to virulence and quorum-sensing mechanisms in K. pneumoniae whose expression is controlled by iron through the Fur regulator. The Fur-regulated genes will be identified by searching the Fur-regulatory sequences, named Fur boxes, on the promoter region of the candidate genes. The putative Fur boxes will be validated and characterized by the EMSA technique and the expression pattern of the genes with validated Fur box will be assessed by real time PCR in K. pneumoniae cells kept in the presence and absence of iron. Finally, the molecular homologous modeling of K. pneumoniae Fur protein will provide further insights on the mechanism of action of the Fur regulator and its respective regulatory sequences. (AU)