# The impact of Elaeagnus angustifolia root exudates on Parafrankia soli NRRL B-16219 exoproteome

## TL;DR

This study explores how root exudates from Elaeagnus angustifolia affect the protein expression of the soil bacterium Parafrankia soli, revealing changes that may aid in host infection.

## Contribution

The study identifies specific protein changes in Parafrankia soli triggered by host root exudates, suggesting a role in symbiotic infection.

## Key findings

- 565 proteins were found to be differentially abundant in response to root exudates.
- Upregulated proteins include Type II/IV secretion system components and EF-Tu, possibly involved in host infection.
- The findings suggest a metabolic reprogramming in the bacterium for symbiotic development.

## Abstract

Root exudates from host plant species are known to play a critical role in the establishment and maintenance of symbiotic relationships with soil bacteria. In this study, we investigated the impact of root exudates from compatible host plant species; Elaeagnus angustifolia on the exoproteome of Parafrankia soli strain NRRL B-16219. A total of 565 proteins were evidenced as differentially abundant, with 32 upregulated and 533 downregulated in presence of the plant exudates. Analysis of the function of these proteins suggests that the bacterial strain is undergoing a complex metabolic reprogramming towards a new developmental phase elicited in presence of host plant root exudates. The upregulation of Type II/IV secretion system proteins among the differentially expressed proteins indicates their possible role in infecting the host plant, as shown for some rhizobia. Additionally, EF-Tu, proteins upregulated in this study, may function as an effector for the T4SSs and trigger plant defense responses. These findings suggest that Parafrankia soli may use EF-Tu to infect the actinorhizal host plant and pave the way for further investigations of the molecular mechanisms underlying the establishment of symbiotic relationships.