Biology subjects

Henderson, S. W.

Publications and source records attributed to Henderson, S. W..

2 recordsLinked to original sources

bioRxiv2024

Protein modelling and thermodynamics reveal that plant cation-chloride cotransporters mediate potassium-chloride symport

Plant cation-chloride-cotransporters (CCC) are proposed to be Na+-K+-2Cl- transporting proteins, although phylogenetically they are closer to K+-Cl- cotransporters (KCC). Conserved features of plant CCC and animal KCC include the presence of predicted K+ and Cl- binding sites, and the absence of a Na+ binding site. Here, we investigated grapevine (Vitis vinifera L.) VvCCC using protein structural modelling and heterologous expression. Our modelling data predicted that 3D folds of VvCCC were more similar to DrNKCC1, but sequences of ion binding sites resembled those of hKCC1. The measurements with VvCCC-injected Xenopus laevis oocytes with VvCCC, localising to plasma membranes, indicated that oocytes were depleted of intracellular Cl-, net 86Rb fluxes, which agreed with thermodynamic predictions for KCC co-transport. 86Rb uptake by VvCCC-injected oocytes was Cl--dependent, did not require external Na+, and was partially inhibited by the non-specific CCC blocker bumetanide - these properties are typical of KCC transporters. A loop diuretic-insensitive Na+ conductance in VvCCC-injected oocytes may account for earlier observations of Na+ uptake by plant CCC proteins in oocytes. Our data suggest plant CCC proteins are likely to function as K+-Cl- cotransporters, which opens avenues to define their mechanistic and biophysical properties and roles in physiology. HighlightBased on predictive structural and experimental data, this study presents novel findings to reveal that plant cation-chloride-cotransporters are likely to function as K+-Cl- symporters.

plant biology↗

bioRxiv2020

GmSALT3 confers shoot Na+ and Cl- exclusion in soybean via two distinct processes.

Soybean (Glycine max) yields are threatened by multiple stresses including soil salinity. GmSALT3 confers net shoot exclusion for both Na+ and Cl- and improves salt tolerance of soybean; however, how the ER-localised GmSALT3 achieves this is unknown. Here, GmSALT3s function was investigated in heterologous systems and near-isogenic lines that contained the full-length GmSALT3 (NIL-T; salt-tolerant) or a truncated transcript Gmsalt3 (NIL-S; salt-sensitive). GmSALT3 restored growth of K+-uptake-defective E. coli and contributed toward net influx and accumulation of Na+, K+, and Cl- in Xenopus laevis oocytes, while Gmsalt3 was non-functional. A time-course analysis of the NILs confirmed that shoot Cl- exclusion breaks down prior to Na+ exclusion, while grafting showed that shoot Na+ exclusion occurs via a root xylem-based mechanism. In contrast, NIL-T plants exhibited significantly greater Cl- content in both the stem xylem and phloem sap compared to NIL-S, indicating that shoot Cl- exclusion likely depends upon novel phloem-based Cl- recirculation. NIL-T shoots grafted on NIL-S roots contained low shoot Cl-, which confirmed that Cl- recirculation is dependent on the presence of GmSALT3 in shoots. Overall, these findings provide new insights on GmSALT3s impact on salinity tolerance and reveal a novel mechanism for shoot Cl- exclusion in plants. HighlightGmSALT3 improves soybean salt tolerance. Here, using heterologous expression, we found GmSALT3 is a functional ion transporter, and, in planta that it confers shoot salt exclusion through root-based Na+ xylem exclusion and shoot-based Cl- exclusion via phloem derived Cl- recirculation.

plant biology↗