Biology subjects

Kakanj, P.

Publications and source records attributed to Kakanj, P..

4 recordsLinked to original sources

bioRxiv2026

Prion-like domains control plastid targeting of PEPSI effectors and PEPSI6-mediated modulation of DXR during root symbiosis

Microbial effectors often act in the apoplast or cytosol, but how they reach host organelles during beneficial plant-fungal interactions remains poorly understood. Here, we identify a class of secreted prion-like effector proteins from the mutualistic root endophyte Serendipita indica, termed PEPSIs. These proteins contain prion-like domains (PrLDs) embedded within intrinsically disordered regions, and three tested PEPSIs require these domains for plastid localization. Focusing on PEPSI6, we show that plastid targeting depends on its PrLD and is associated with engagement of plastid import and proteostasis machinery. In plastids, PEPSI6 associates with 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), promotes DXR accumulation, alters methylerythritol phosphate pathway metabolites, and enhances tolerance to the DXR inhibitor fosmidomycin. PEPSI6 also undergoes apoplastic C-terminal CAP-domain processing, and its colonization-promoting activity persists after PrLD deletion, indicating a plastid-targeting-independent function. Overall, this work identifies PrLDs as noncanonical plastid-targeting elements in PEPSI effectors and reveals DXR as a target of fungal manipulation during root symbiosis. HighlightsO_LIPrion-like domains control plastid targeting of selected PEPSI effectors. C_LIO_LIPEPSI6 associates with DXR and promotes its accumulation in plastids. C_LIO_LIPEPSI6 alters MEP-pathway metabolites and increases tolerance to fosmidomycin. C_LIO_LIApoplastic processing reveals a plastid-independent PEPSI6 activity during root symbiosis. C_LI

plant biology↗

bioRxiv2024

Lysosomal uptake of mtDNA mitigates heteroplasmy

Mitochondrial DNA is exposed to multiple insults produced by normal cellular function. Upon mtDNA replication stress the mitochondrial genome transfers to endosomes where it is degraded. Here, using proximity proteomics we found that mtDNA replication stress leads to the rewiring of the mitochondrial proximity proteome, increasing mitochondria association with lysosomal and vesicle-associated proteins, such as the GTPase RAB10 and the retromer. We found that upon mtDNA replication stress, RAB10 enhances mitochondrial fragmentation and relocates from the ER to lysosomes containing mtDNA. The retromer enhances and coordinates the expulsion of mitochondrial matrix components through mitochondrial-derived vesicles, and mtDNA with direct transfer to lysosomes. Using a Drosophila model carrying a long deletion on the mtDNA ({Delta}mtDNA), we evaluated in vivo the role of the retromer in mtDNA extraction and turnover in the larval epidermis. The presence of {Delta}mtDNA elicits the activation of a specific transcriptome profile related to counteract mitochondrial damage. Expression of the retromer component Vps35 is sufficient to restore mtDNA homoplasmy and mitochondrial defects associated with {Delta}mtDNA. Our data reveal novel regulators involved in the specific elimination of mtDNA. We demonstrate that modulation of the retromer in vivo is a successful mechanism to restore mitochondrial function associated with mtDNA damage.

cell biology↗

bioRxiv2021

Autophagy suppression by TORC1 maintains epithelial plasma membrane integrity and inhibits syncytium formation

Epithelial wound healing in Drosophila involves the formation of multinucleate cells surrounding the wound. We show that autophagy, a cellular degradation process often deployed in stress responses, is required for the formation of a multinucleated syncytium during wound healing. In addition, uncontrolled autophagy in the unwounded epidermis leads to the degradation of endo-membranes and the lateral plasma membrane, while the apical and basal membranes and the epithelial barrier function remain intact. Proper functioning of TORC1 is needed to prevent autophagy from destroying the larval epidermis, which depends on membrane isolation and phagophore expansion, but does not require the fusion of autophagosomes to lysosomes. Our findings reveal a function for TORC1-mediated regulation of autophagy in maintaining membrane integrity and homeostasis in the epidermis and during wound healing. Finally, autophagy can counteract experimentally induced nuclear defects resembling laminopathies. Key findingsO_LIA novel role for TORC1/autophagy pathway to control plasma membrane integrity and homeostasis. C_LIO_LIAutophagy as the only known necessary and sufficient inducer of syncytium formation in the epithelium and during wound healing. C_LI

cell biology↗

bioRxiv2019

Long-term in vivo imaging of Drosophila larvae

The Drosophila larva has been used to investigate many processes in cell biology, including morphogenesis, physiology, responses to drugs and new therapeutic compounds. Despite its enormous potential as a model system, it has technical limitations in cases where longer-term live imaging is necessary, because of the lack of efficient methods for immobilising larvae for extended periods. We describe here a simple procedure for anaesthetisation and long-term in vivo imaging of the epidermis and other larval organs including gut, imaginal discs, neurons, fat body, tracheae and haemocytes, and show a procedure for probing cell properties by laser ablation. We include a survey of different anaesthetics, showing that short exposure to diethyl ether is the most effective for long-term immobilisation of larvae. This method does not require specific expertise beyond basic Drosophila genetics and husbandry, and confocal microscopy. It enables high-resolution studies of many systemic and sub-cellular processes in larvae.

cell biology↗