Biology subjects

Baik, S.

Publications and source records attributed to Baik, S..

3 recordsLinked to original sources

bioRxiv2026

Cystinosin/Ers1 functions in redox homeostasis in the early secretory pathway

Cystinosis is an autosomal recessive inherited disorder caused by mutations in the CTNS gene, which encodes the highly conserved transmembrane protein cystinosin, a proton/cystine co-transporter at the lysosome membrane. However, reduction of cystine load in the lysosomes is insufficient to treat key disease symptoms, indicating that cystinosin performs additional disease-relevant functions. Here, we report that Ers1, the yeast homolog of cystinosin, localizes to and functions in the early secretory pathway. We provide evidence that Ers1 does not transport cystine. Ers1 genetically interacts with early secretory pathway recycling adaptors and redox-active Fe-S cluster-binding proteins. Notably, cystinosin-LKG, the extra-lysosomal localized splicing isoform of cystinosin, can functionally replace Ers1 in yeast. Collectively, our work uncovers a conserved role of cystinosin/Ers1 in the early secretory pathway, offering new molecular insights for understanding cystinosis pathology.

cell biology↗

bioRxiv2024

Gene editing of the E3 ligase PIRE1 fine-tunes ROS production for enhanced bacterial disease resistance in tomato

Reactive oxygen species (ROS) accumulation is required for effective plant defense. Accumulation of the Arabidopsis NADPH oxidase RBOHD is regulated by phosphorylation of a conserved C-terminal residue (T912) leading to ubiquitination by the RING E3 ligase PIRE. Arabidopsis PIRE knockouts exhibit enhanced ROS production and resistance to the foliar pathogen Pseudomonas syringae. Here, we identified 170 PIRE homologs, which emerged in Tracheophytes and expanded in Angiosperms. We investigated the role of Solanum lycopersicum (tomato) PIRE homologs in regulating ROS production, RBOH stability, and disease resistance. Mutational analyses of residues corresponding to T912 in the tomato RBOHD ortholog, SlRBOHB, affected protein accumulation and ROS production in a PIRE-dependent manner. Using CRISPR-cas9, we generated mutants in two S. lycopersicum PIRE homologs (SlPIRE). SlPIRE1 edited lines (Slpire1) in the tomato cultivar M82 displayed enhanced ROS production upon treatment with flg22, an immunogenic epitope of flagellin. Furthermore, Slpire1 exhibited decreased disease symptoms and bacterial accumulation when inoculated with foliar bacterial pathogens Pseudomonas syringae and Xanthomonas campestris. However, Slpire1 exhibited similar levels of colonization as wild type upon inoculation with diverse soilborne pathogens. These results indicate that phosphorylation and ubiquitination crosstalk regulate RBOHs in multiple plant species, and PIRE is a promising target for foliar disease control. This study also highlights the pathogen-specific role of PIRE, indicating its potential for targeted manipulation to enhance foliar disease resistance without affecting root-associated interactions, positioning PIRE as a promising target for improving overall plant health.

plant biology↗

bioRxiv2024

Direct binding of a fungal effector by the wheat RWT4 tandem kinase activates defense

Plants have intricate innate immune receptors that detect pathogens. Research has intensely focused on two receptor classes recognizing external and internal threats. Recent research has identified a class of disease resistance proteins called tandem kinase proteins (TKPs). We investigated RWT4, a wheat TKP that confers resistance to the devastating fungal pathogen Magnaporthe oryzae. We established a rice protoplast system, revealing RWT4 specifically recognizes the AvrPWT4 effector, leading to the transcription of defense genes and inducing cell death. RWT4 possesses both kinase and pseudokinase domains, with its kinase activity essential for defense. RWT4 directly interacts with and transphosphorylates AvrPWT4. Biolayer interferometry revealed both RWT4 kinase and pseudokinase regions bind the effector. Sequence similarity and structural modeling revealed an integrated partial kinase duplication in RWT4s kinase region as critical for effector interaction and defense activation. Collectively, these findings demonstrate that TKPs can directly bind a recognized effector, leading to downstream defense activation.

plant biology↗