PelD is required downstream of c-di-GMP for host specialization of Pseudomonas lurida

BACKGROUND: The bacterial second messenger c-di-GMP is known to influence the formation of biofilms and thereby persistence of pathogenic and beneficial bacteria in hosts. A previous evolution experiment with Pseudomonas lurida MYb11, occasional symbiont of the nematode Caenorhabditis elegans, led to the emergence of host-specialized variants with elevated intracellular c-di-GMP. Thus far, the molecular underpinnings of c-di-GMP-mediated host specialization were unknown in this symbiosis. Therefore, the current study aimed at identifying candidate molecular processes by combining transcriptomic and functional genetic analyses. RESULTS: We found that MYb11 host specialists differentially expressed genes related to attachment, motility and biofilm production, including pelD from the pel gene cluster. pelD deletion resulted in reduced intra-host competitive fitness, lower bacterial numbers in C. elegans and loss of biofilm biomass. CONCLUSION: Our results identify pelD as a previously unknown key modulator of beneficial symbiont-host associations that acts downstream of c-di-GMP.

• Czerwinski, A.
• Löwenstrom, J.
• Franzenburg, S.
• Groth, E. E.
• Obeng, N.
• Schulenburg, H.