A Barley Efflux Transporter Operates in a Na+-Dependent Manner, as Revealed by a Multidisciplinary Platform.

Plant growth and survival depend upon the activity of membrane transporters that control the movement and distribution of solutes into, around, and out of plants. Although many plant transporters are known, their intrinsic properties make them difficult to study. In barley (Hordeum vulgare), the root anion-permeable transporter Bot1 plays a key role in tolerance to high soil boron, facilitating the efflux of borate from cells. However, its three-dimensional structure is unavailable and the molecular basis of its permeation function is unknown. Using an integrative platform of computational, biophysical, and biochemical tools as well as molecular biology, electrophysiology, and bioinformatics, we provide insight into the origin of transport function of Bot1. An atomistic model, supported by atomic force microscopy measurements, reveals that the protein folds into 13 transmembrane-spanning and five cytoplasmic α-helices. We predict a trimeric assembly of Bot1 and the presence of a Na(+) ion binding site, located in the proximity of a pore that conducts anions. Patch-clamp electrophysiology of Bot1 detects Na(+)-dependent polyvalent anion transport in a Nernstian manner with channel-like characteristics. Using alanine scanning, molecular dynamics simulations, and transport measurements, we show that conductance by Bot1 is abolished by removal of the Na(+) ion binding site. Our data enhance the understanding of the permeation functions of Bot1.

Factors associated with access to care and healthcare utilization in the homeless population of England.

Background: People experiencing homelessness are known to have complex health needs, which are often compounded by poor access to healthcare. This study investigates the individual-level factors associated with access to care and healthcare utilization among homeless people in England. Methods: A cross-sectional sample of 2505 homeless people from 19 areas of England was used to investigate associations with access to care and healthcare utilization. Results: Rough sleepers were much less likely to be registered with a general practitioner (GP) (odds ratio (OR) 0.45, 95% confidence interval (CI) 0.30-0.66) than single homeless in accommodation (reference group) or the hidden homeless (OR 1.48, 95% CI 0.88-2.50). Those who had recently been refused registration by a GP or dentist also had lower odds of being admitted to hospital (OR 0.67, 95% CI 0.49-0.91) or using an ambulance (OR 0.73, 95% CI 0.54-0.99). Conclusions: The most vulnerable homeless people face the greatest barriers to utilizing healthcare. Rough sleepers have particularly low rates of GP registration and this appears to have a knock-on effect on admission to hospital. Improving primary care access for the homeless population could ensure that some of the most vulnerable people in society are able to access vital hospital services which they are currently missing out on.