Biology subjects

Han, K.-H.

Publications and source records attributed to Han, K.-H..

3 recordsLinked to original sources

bioRxiv2024

Targeted Degradation of MYC2 through MPK6 Phosphorylation Reveals Mechanisms and Implications for JA Signaling

MYC2 is a key regulator in the Jasmonic acid (JA) signaling pathway, yet the mechanisms governing its stability remain unclear. In this study, we demonstrate that MYC2 is degraded by MPK6 under JA signaling. Through yeast two-hybrid and co-immunoprecipitation assays, and in vitro kinase assay, we show that MPK6 directly interacts with and phosphorylates MYC2. Additionally, MYC2 transcriptional activity is enhanced in the mpk6 mutant. Further, MPK6 phosphorylates MYC2 at threonine 328, leading to its degradation. These findings suggest that MPK6 drives MYC2 degradation by specifically phosphorylating threonine 328 within the JA signaling pathway.

plant biology↗

bioRxiv2020

Transcriptomic, protein-DNA interaction, and metabolomic studies of VosA, VelB, and WetA in Aspergillus nidulans asexual spores

In filamentous fungi, asexual development involves morphological differentiation and metabolic changes leading to the formation of asexual spores. The process of asexual spore formation in Aspergillus is precisely regulated by multiple transcription factors (TFs), including VosA, VelB, and WetA, and these three TFs are key regulators of the formation and maturation of asexual spores (conidia) in Aspergillus including the model fungus Aspergillus nidulans. To gain a mechanistic insight on the complex regulatory roles of these TFs in asexual spores, we conducted genome-wide studies on the expression, protein-DNA interactions, and primary and secondary metabolism employing A. nidulans conidia. RNA sequencing and chromatin immunoprecipitation-sequencing data have revealed that the three TFs directly or indirectly regulate the expression of genes associated with spore-wall formation/integrity, asexual development, and secondary metabolism. In addition, metabolomics analyses of wild-type and mutant conidia indicate that these three TFs regulate a diverse array of primary and secondary metabolism. In summary, WetA, VosA, and VelB play inter-dependent and distinct roles governing morphological development and primary/secondary metabolic remodeling in Aspergillus conidia. ImportanceFilamentous fungi produce a vast number of asexual spores that act as reproductive and propagator cells. These spores affect humans, due to the infectious or allergenic nature of the propagule. Aspergillus species produce asexual spores called conidia and their formation involves morphological development and metabolic changes, and the associated regulatory systems are coordinated by spore-specific transcription factors. To understand the underlying global regulatory programs and cellular outcomes associated with conidia formation, functional genomic and metabolomic analyses were performed in the model fungus Aspergillus nidulans. Our results show that the fungus specific WetA/VosA/VelB transcription factors govern the coordination of morphological and chemical developments during sporogenesis. The results of this study provide insights into the genetic regulatory networks about how morphological developments and metabolic changes are coordinated in fungi. The findings are relevant for other Aspergillus species such as the major human pathogen Aspergillus fumigatus and the aflatoxin-producer Aspergillus flavus.

microbiology↗

bioRxiv2019

WT and A53T α-synuclein systems: Melting Diagram and its new interpretation

Parkinsons disease is connected with abnormal -synuclein (S) aggregation. Energetics of potential barriers governing motions of hydration water is examined. Information about the distributions and heights of potential barriers is gained by a thermodynamical approach. The ratios of the heterogeneous water-binding interfaces measure proteins structural disorder. All S forms possess secondary structural elements though they are intrinsically disordered. Monomers are functional at the lowest potential barriers, where mobile hydration water exists, with monolayer coverage of mobile hydration. The S monomer contains 33% secondary structure and is more compact than a random coil. A53T S monomer has a more open structure than the wild type. Monomers realize all possible hydrogen bonds. Half of the mobile hydration water amount for monomers is missing in S oligomers and S amyloids. Oligomers are ordered by 66%. Mobile water molecules in the first hydration shell of amyloids are the weakest bound compared to other forms. Wild type and A53T amyloids show identical, low-level hydration, and are considered as disordered to 75%.\n\nStatement of SignificanceAggregation of -synuclein into oligomers, amyloid fibrils is a hallmark of Parkinsons disease. A thermodynamic approach provides information on the heterogeneity of protein-water bonds in the wild type and A53T mutant monomers, oligomers, amyloids. This information can be related to ratios of heterogeneous water-binding interfaces, which measure the proteins structural disorder. Both -synuclein monomers are intrinsically disordered. The monomers nevertheless have 33% secondary structure. They are functional as long as mobile water molecules surround them. They realize every possible H-bonds with water. Oligomers are like globular proteins with 66% ordered structure. Amyloids are disordered to 75% and are poorly hydrated with loosely bound water. Their hydration is identical. Oligomers, amyloids have only half as much hydrating mobile water as monomers.

biophysics↗