Bacterial hydrophilins promote pathogen desiccation tolerance

Acinetobacter baumannii is a leading cause of hospital-acquired infections, where outbreaks are driven by its ability to persist on surfaces in a desiccated state. Here, we show that A. baumannii causes more virulent pneumonia following desiccation and profile the genetic requirements for desiccation. We find that desicca-tion tolerance is enhanced upon the disruption of Lon protease, which targets unfolded and aggregated pro-teins for degradation. Notably, two bacterial hydrophilins, DtpA and DtpB, are transcriptionally upregulated in Dlon via the two-component regulator, BfmR. These proteins, both hydrophilic and intrinsically disordered, promote desiccation tolerance in A. baumannii. Additionally, recombinant DtpA protects purified enzymes from inactivation and improves the desiccation tolerance of a probiotic bacterium when heterologously ex-pressed. These results demonstrate a connection between environmental persistence and pathogenicity in A. baumannii, provide insight into the mechanisms of extreme desiccation tolerance, and reveal potential ap-plications for bacterial hydrophilins in the preservation of protein-and live bacteria-based pharmaceuticals.

Automated summary

This study reveals that Acinetobacter baumannii causes more virulent pneumonia following desiccation and identifies the genetic requirements for desiccation. The disruption of Lon protease enhances desiccation tolerance, while bacterial hydrophilins DtpA and DtpB play a crucial role in this process.