Single particle cryo-EM structure of the outer hair cell motor protein prestin

The mammalian outer hair cell (OHC) protein prestin (Slc26a5) differs from other Slc26 family members due to its unique piezoelectric-like property that drives OHC electromotility, the putative mechanism for cochlear amplification. Here, we use cryo-electron microscopy to determine prestin’s structure at 3.6 Å resolution. Prestin is structurally similar to the anion transporter Slc26a9. It is captured in an inward-open state which may reflect prestin’s contracted state. Two well-separated transmembrane (TM) domains and two cytoplasmic sulfate transporter and anti-sigma factor antagonist (STAS) domains form a swapped dimer. The transmembrane domains consist of 14 transmembrane segments organized in two 7+7 inverted repeats, an architecture first observed in the bacterial symporter UraA. Mutation of prestin’s chloride binding site removes salicylate competition with anions while retaining the prestin characteristic displacement currents (Nonlinear Capacitance), undermining the extrinsic voltage sensor hypothesis for prestin function.

Structure and function of an Arabidopsis thaliana sulfate transporter

Plant sulfate transporters (SULTR) mediate absorption and distribution of sulfate (SO42−) and are essential for plant growth; however, our understanding of their structures and functions remains inadequate. Here we present the structure of a SULTR from Arabidopsis thaliana, AtSULTR4;1, in complex with SO42− at an overall resolution of 2.8 Å. AtSULTR4;1 forms a homodimer and has a structural fold typical of the SLC26 family of anion transporters. The bound SO42− is coordinated by side-chain hydroxyls and backbone amides, and further stabilized electrostatically by the conserved Arg393 and two helix dipoles. Proton and SO42− are co-transported by AtSULTR4;1 and a proton gradient significantly enhances SO42− transport. Glu347, which is ~7 Å from the bound SO42−, is required for H+-driven transport. The cytosolic STAS domain interacts with transmembrane domains, and deletion of the STAS domain or mutations to the interface compromises dimer formation and reduces SO42− transport, suggesting a regulatory function of the STAS domain.

Genome-wide transcriptomic analysis of the forebrain of postnatal Slc13a4+/− mice

Objective Sulfation is an essential physiological process that regulates the function of a wide array of molecules involved in brain development. We have previously shown expression levels for the sulfate transporter Slc13a4 to be elevated during postnatal development, and that sulfate accumulation in the brains of Slc13a4+/− mice is reduced, suggesting a role for this transporter during this critical window of brain development. In order to understand the pathways regulated by cellular sulfation within the brain, we performed a bulk RNA-sequencing analysis of the forebrain of postnatal day 20 (P20) Slc13a4 heterozygous mice and wild-type litter mate controls. Data description We performed an RNA transcriptomic based sequencing screen on the whole forebrain from Slc13a4+/− and Slc13a4+/+mice at P20. Differential expression analysis revealed 90 differentially regulated genes in the forebrain of Slc13a4+/− mice (a p-value of 0.1 was considered as significant). Of these, 55 were upregulated, and 35 were downregulated in the forebrain of heterozygous mice. Moreover, when we stratified further with a ± 1.2 fold-change, we observed 38 upregulated, and 16 downregulated genes in the forebrain of heterozygous mice. This resource provides a useful tool to interrogate which pathways may require elevated sulfate levels to drive normal postnatal development of the brain.

Glucose 6-phosphate transport regulatory protein UhpA regulates the virulent genes in Edwardsiella piscicida

Edwardsiella piscicida (E. piscicida) is an important zoonotic pathogen, which infects animals by colonizing the intestine. Glucose 6-phosphate (Glu6P) was an important carbohydrate in intestine and could be used as a regulate signal. Here we identify a virulence-regulating pathway named Glu6P transport regulatory protein UhpA, which affects the virulent genes of hemolysins, flagellar, T3SS, T6SS and metabolism related genes how to promote E. piscicida infect the host. The results showed that the metabolism related gene expression of cysteine synthase (orf 1134) and sulfate transporter (ychM) in the uhpA mutant strain ΔuhpA was 0.76-fold and 0.68-fold lower than the ones in the wild strains (P < 0.05), the gene expression of ethA and ethB in the ΔuhpA strain was 0.80-fold and 0.72-fold lower than the ones in the wild strains (P < 0.05). However, the gene expression of fliC and flgN in the ΔuhpA was 1.51-fold and 1.21-fold higher than the ones in the wild strains (P < 0.05), the gene expression of T3SS (esrB and esrC) and T6SS (evpB and evpC) in the ΔuhpA was 1.27-fold, 1.13-fold 1.28-fold and 1.23-fold higher than the ones in the wild strains (P < 0.05). Besides, the survival rate of fish challenged with E. piscicida EIB202 and ΔuhpA was 50% and 30% respectively. These suggested that although the uhpA gene deletion decreased the metabolic level and the hemolysins related gene expression in E. piscicida, the uhpA gene could down regulate the key virulent gene expression to decrease the pathogenicity of E. piscicida in fish.