An investigation into the Omp85 protein BamK in hypervirulent Klebsiella pneumoniae, and its role in outer membrane biogenesis

Abstract

Members of the Omp85 protein superfamily have important roles in Gram-negative bacteria, with the archetypal protein BamA being ubiquitous given its essential function in the assembly of outer membrane proteins. In some bacterial lineages, additional members of the family exist and, in most of these cases, the function of the protein is unknown. We detected one of these Omp85 proteins in the pathogen Klebsiella pneumoniae B5055, and refer to the protein as BamK. Here, we show that bamK is a conserved element in the core genome of Klebsiella, and its expression rescues a loss-of-function ∆bamA mutant. We developed an E. coli model system to measure and compare the specific activity of BamA and BamK in the assembly reaction for the critical substrate LptD, and find that BamK is as efficient as BamA in assembling the native LptDE complex. Comparative structural analysis revealed that the major distinction between BamK and BamA is in the external facing surface of the protein, and we discuss how such changes may contribute to a mechanism for resistance against infection by bacteriophage.

Novel virulence factor Cba induces antibody-dependent enhancement (ADE) of Streptococcus suis Serotype 9 infection in a mouse model

“…To further understand the mechanism of SS-host interaction, an in-depth study of the virulence genes and proteins in SS is necessary. Bacterial surface proteins containing the LPxTG motif associated with bacterial virulence, such as the Cbp40 ( Zhang et al., 2013 ), HP0197 ( Zhang et al., 2009 ), and Sao ( Li et al., 2007 ) proteins of SS, the SpaA protein family of Erysipelothrix insidiosa , and the Omp85 protein family of gram-negative bacteria ( Torres et al., 2018 ), are highly immunogenic and potentially valuable for the development of relevant vaccines. In a preliminary study, strain DN13 of SS9 was isolated from a pig that died of septicemia in Chenzhou, Hunan Province, China.…”