The PTS Ntr -KdpDE-KdpFABC Pathway Contributes to Low Potassium Stress Adaptation and Competitive Nodulation of Sinorhizobium fredii
The rhizobium-legume symbiosis is essential for sustainable agriculture by reducing nitrogen fertilizer input, but its efficiency varies under fluctuating soil conditions and resources. The nitrogen-related phosphotransferase system (PTS ) consisting of PtsP, PtsO, and PtsN is required for optimal n...
Saved in:
Published in | mBio Vol. 13; no. 3; p. e0372121 |
---|---|
Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
28.06.2022
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | The rhizobium-legume symbiosis is essential for sustainable agriculture by reducing nitrogen fertilizer input, but its efficiency varies under fluctuating soil conditions and resources. The nitrogen-related phosphotransferase system (PTS
) consisting of PtsP, PtsO, and PtsN is required for optimal nodulation and nitrogen fixation efficiency of the broad-host-range Sinorhizobium fredii CCBAU45436 associated with diverse legumes, though the underlying mechanisms remain elusive. This work characterizes the PtsN-KdpDE-KdpFABC pathway that contributes to low potassium adaptation and competitive nodulation of CCBAU45436. Among three PtsN, PtsN
is the major functional homolog. The unphosphorylated PtsN
binds the sensory kinase KdpD through a non-canonical interaction with the GAF domain of KdpD, while the region covering HisKA-HATPase domains mediates the interaction of KdpD with the response regulator KdpE. KdpE directly activates the
operon encoding the conserved high-affinity potassium uptake system. Disruption of this signaling pathway leads to reduced nodule number, nodule occupancy, and low potassium adaptation ability, but without notable effects on rhizoplane colonization. The induction of key nodulation genes
and
in host roots during early symbiotic interactions is impaired when inoculating the
mutant that shows delayed nodulation. The nodulation defect of the
mutant can be rescued by supplying replete potassium. Potassium is actively consumed by both prokaryotes and eukaryotes, and components of the PTS
-KdpDE-KdpFABC pathway are widely conserved in bacteria, highlighting the global importance of this pathway in bacteria-host interactions.
In all ecological niches, potassium is actively consumed by diverse prokaryotes and their interacting eukaryote hosts. It is only just emerging that potassium is a key player in host-pathogen interactions, and the role of potassium in mutualistic interactions remains largely unknown. This work is focused on the mutualistic symbiosis between rhizobia and legumes. We report that the nitrogen-related phosphotransferase system PTS
, the two-component system KdpDE, and the high-affinity potassium uptake system KdpFABC constitute a pathway that is important for low potassium adaptation and optimal nodulation of rhizobia. Given the widely conserved PTS
, KdpDE, and KdpFABC in bacteria and increasing knowledge on microbiome for various niches, the PTS
-KdpDE-KdpFABC pathway can be globally important in the biosphere. |
---|---|
ISSN: | 2150-7511 2150-7511 |
DOI: | 10.1128/mbio.03721-21 |