Evolutionary diversity and structural dynamics of the outer membrane protein Ail in Yersinia

Yersinia pestis Ail (attachment invasion locus protein) is an outer membrane β-barrel made up of a cylindrical, anti-parallel β-sheet with a hydrophobic peripheral and a hydrophilic center. It has a diverse set of functions that facilitate successful resistance to defense mechanisms of the host organism in the process of host-pathogen interactions. Among them are inhibition of the complement bactericidal activity, attachment and Yersinia outer proteins delivery to host tissue, prevention of polymorphonuclear leukocytes recruitment to the lymph nodes, and inhibition of the inflammatory response. However, previous studies have all focused almost exclusively on a single Ail isoform. Here, we analyze and discuss the polymorphisms of Y. pestis Ail, their potential influence on structural dynamics as well as intrinsic disorder predisposition of this protein. The natural polymorphism is restricted to functionally important loops. We use molecular dynamics simulations and intrinsic disorder predictions to assess how these polymorphisms affect Ail conformational dynamics, revealing that minor sequence divergences correlate with distinst dynamic profiles indicating isoform-specific modulation of Ail function.