# Proteins of the SubB family provide multiple mechanisms of serum resistance in Yersinia pestis

## TL;DR

This paper shows that certain proteins in Yersinia pestis help it resist the body's immune system, specifically the serum complement system.

## Contribution

The study identifies ypo0337 and SubB-like proteins as novel serum resistance factors in Yersinia pestis.

## Key findings

- YPO0337 recruits complement regulators to confer serum resistance in Yersinia pestis.
- SubB from Escherichia coli can restore serum resistance in Y. pestis Δypo0337 mutants.
- SubB family proteins act as virulence factors through unique mechanisms in different bacteria.

## Abstract

The serum complement system is a cornerstone element of the innate immune response. Bacterial resistance to this system is a multifaceted process involving various proteins and molecular mechanisms. Here, we report several genes required for the growth of Yersinia pestis in serum. Among them, we found that ypo0337 encodes an outer-membrane-associated lectin that recruits factor H, C4BP and hemopexin, conferring resistance to the serum complement system. YPO0337 displays high sequence similarity with the SubB subunit of the AB5 toxin from Escherichia coli, as well as other SubB-like proteins, and subB from E. coli restores the ability of Y. pestis Δypo0337 mutant to resist to serum complement. Altogether, the data suggest that at least two members of the SubB protein family function as virulence factors, conferring resistance to serum complement through a unique mode of action.