Structural characterization of Fis - A transcriptional regulator from pathogenic Pasteurella multocida essential for expression of virulence factors.

Pasteurella multocida is responsible behind a variety of diseases in animals. The disease causing substance of this bacterium is a capsular polysaccharide. The expression of the gene that codes for the bacterial capsule is regulated by the protein Fis. Fis also regulates the expression of various different genes in P. multocida. So far there have been no previous reports that depict the characterization of Fis from P. multocida from a structural point of view. In the present work, an attempt has been made to characterize Fis by in silico methods. The structure of Fis was built by comparative modeling technique. The model of Fis was then docked onto the corresponding promoter regions of the gene encoding the capsular polysaccharide. The docked complexes of promoter DNA with Fis protein were subjected to molecular dynamics simulations to identify the mode of DNA-protein interactions. The DNA binding amino acid residues from the Fis protein were identified. And a mechanistic detail of the DNA binding interactions was predicted. So far, this is the first report that depicts the mechanistic details of Fis-DNA interactions involved in the regulation of gene expression by Fis protein. This work may therefore be useful to illuminate the still obscure molecular mechanism behind the disease propagation by P. multocida.