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4-Hydroxyphenylpyruvate dioxygenase (HPPD) is pivotal in tyrosine metabolism and essential for plant survival. Its inhibition leads to leaf bleaching and plant death. While current HPPD inhibitors are effective, they pose phytotoxicity risks and may contribute to herbicide resistance. Here, we investigated the inhibitory potential of sethoxydim and atovaquone, which traditionally target acetyl-CoA carboxylase and the cytochrome bc1 complex, respectively. Both atovaquone and the degradation product of sethoxydim exhibited moderate HPPD inhibitory activity. But the mechanism by which sethoxydim inhibited HPPD remained unclear. Therefore, we embarked on an investigation into the crystal structure of the complex, with the aim of elucidating its precise binding mode. Our findings revealed that sethoxydim degrades in solution, producing dealkoxy sethoxydim as the active component in HPPD inhibition. Structural analysis elucidated the binding modes of atovaquone and dealkoxy sethoxydim with HPPD. These binding motifs represent novel pharmacophores and offer promising leads for developing HPPD inhibitors with improved pesticidal profiles.

Abstract The TMEM63 family proteins (A, B, and C), calcium-permeable channels in animals that are preferentially activated by hypo-osmolality, have been implicated in various physiological functions. Deficiency of these channels would cause many diseases including hearing loss. However, their structures and physiological roles are not yet well understood. In this study, we determine the cryo-electron microscopy (cryo-EM) structure of the mouse TMEM63C at 3.56 Å, and revealed structural differences compared to TMEM63A, TMEM63B, and the plant orthologues OSCAs. Further structural guided mutagenesis and calcium imaging demonstrated the important roles of the coupling of TM0 and TM6 in channel activity. Additionally, we confirm that TMEM63C exists primarily as a monomer under physiological conditions, in contrast, TMEM63B is a mix of monomer and dimer in cells, suggesting that oligomerization is a regulatory mechanism for TMEM63 proteins.

4-Hydrophenylpyruvate dioxygenase (HPPD), a key enzyme involved in tyrosine catabolism, has long been considered a promising target for herbicides and drugs. Several types of HPPD inhibitors have been developed as high-potency drugs or herbicides. Understanding the structural basis of the binding of these inhibitors with HPPD will be beneficial for the development of inhibitors containing novel scaffolds. However, only limited structural information regarding the binding of triketone and pyrazole derivatives with HPPD has been reported. Here, the crystal structures of HPPD complexed with inhibitors containing different scaffolds, including triketone, pyrazole, isoxazole, heterocyclic amide, and quinazolindione derivatives, were comprehensively analyzed. Detailed binding modes of isoxazole and heterocyclic amide derivatives with HPPD were first revealed, facilitating further structural optimization. The binding mode of compound 2 with HPPD suggests that both oxygen and nitrogen atoms can mediate coordination with the metal ion. These results will provide the structure-based rational design of novel HPPD inhibitors.

Phosphatidylinositol phosphates (PIPs) and cholesterol are known to regulate the function of late endosomes and lysosomes (LELs). Here authors unveil a mechanism by which PI(4,5)P2/PI(3,4)P2 allosterically enhances ORP1-mediated cholesterol exit from LELs.

ORP5/8 are endoplasmic reticulum (ER) membrane proteins implicated in lipid trafficking that localize to ER-plasma membrane (PM) contacts and maintain membrane homeostasis. Here the authors show that PtdIns(4,5)P 2 plays a critical role in the targeting and function of ORP5/8 at the PM.

Discovering and engineering herbicide-resistant genes is a crucial challenge in crop breeding. This study focuses on the 4-hydroxyphenylpyruvate dioxygenase Inhibitor Sensitive 1-Like (HSL) protein, prevalent in higher plants and exhibiting weak catalytic activity against many β-triketone herbicides (β-THs). The crystal structures of maize HSL1A complexed with β-THs were elucidated, identifying four essential herbicide-binding residues and explaining the weak activity of HSL1A against the herbicides. Utilizing an artificial evolution approach, we developed a series of rice HSL1 mutants targeting the four residues. Then, these mutants were systematically evaluated, identifying the M10 variant as the most effective in modifying β-THs. The initial active conformation of substrate binding in HSL1 was also revealed from these mutants. Furthermore, overexpression of M10 in rice significantly enhanced resistance to β-THs, resulting in a notable 32-fold increase in resistance to methyl-benquitrione. In conclusion, the artificially evolved M10 gene shows great potential for the development of herbicide-resistant crops. [ABSTRACT FROM AUTHOR]

ORP5 and ORP8, members of the oxysterol-binding protein (OSBP)-related proteins (ORP) family, are endoplasmic reticulum membrane proteins implicated in lipid trafficking. ORP5 and ORP8 are reported to localize to endoplasmic reticulum-plasma membrane junctions via binding to phosphatidylinositol-4-phosphate (PtdIns(4)P), and act as a PtdIns(4)P/ phosphatidylserine counter exchanger between the endoplasmic reticulum and plasma membrane. Here we provide evidence that the pleckstrin homology domain of ORP5/8 via PtdIns(4,5)P2, and not PtdIns(4)P binding mediates the recruitment of ORP5/8 to endoplasmic reticulum-plasma membrane contact sites. The OSBP-related domain of ORP8 can extract and transport multiple phosphoinositides in vitro, and knocking down both ORP5 and ORP8 in cells increases the plasma membrane level of PtdIns(4,5)P2 with little effect on PtdIns(4)P. Overall, our data show, for the first time, that phosphoinositides other than PtdIns (4)P can also serve as co-exchangers for the transport of cargo lipids by ORPs. [ABSTRACT FROM AUTHOR]