The intrinsically disordered region of GCE protein adopts a more fixed structure by interacting with the LBD of the nuclear receptor FTZ-F1

Mesophiles vs. Thermophiles: Untangling the Hot Mess of Intrinsically Disordered Proteins and Growth Temperature of Bacteria

The dynamic structures and varying functions of intrinsically disordered proteins (IDPs) have made them fascinating subjects in molecular biology. Investigating IDP abundance in different bacterial species is crucial for understanding adaptive strategies in diverse environments. Notably, thermophilic bacteria have lower IDP abundance than mesophiles, and a negative correlation with optimal growth temperature (OGT) has been observed. However, the factors driving these trends are yet to be fully understood. We examined the types of IDPs present in both mesophiles and thermophiles alongside those unique to just mesophiles. The shared group of IDPs exhibits similar disorder levels in the two groups of species, suggesting that certain IDPs unique to mesophiles may contribute to the observed decrease in IDP abundance as OGT increases. Subsequently, we used quasi-independent contrasts to explore the relationship between OGT and IDP abundance evolution. Interestingly, we found no significant relationship between OGT and IDP abundance contrasts, suggesting that the evolution of lower IDP abundance in thermophiles may not be solely linked to OGT. This study provides a foundation for future research into the intricate relationship between IDP evolution and environmental adaptation. Our findings support further research on the adaptive significance of intrinsic disorder in bacterial species.

Interaction patterns of methoprene-tolerant and germ cell-expressed Drosophila JH receptors suggest significant differences in their functioning

Methoprene-tolerant (Met) and germ cell-expressed (Gce) proteins were shown to be juvenile hormone (JH) receptors of Drosophila melanogaster with partially redundant functions. We raised the question of where the functional differentiation of paralogs comes from. Therefore, we tested Met and Gce interaction patterns with selected partners. In this study, we showed the ability of Gce and its C-terminus (GceC) to interact with 14-3-3 in the absence of JH. In contrast, Met or Met C-terminus (MetC) interactions with 14-3-3 were not observed. We also performed a detailed structural analysis of Met/Gce interactions with the nuclear receptor fushi tarazu factor-1 (Ftz-F1) ligand-binding domain. We showed that GceC comprising an Ftz-F1-binding site and full-length protein interacts with Ftz-F1. In contrast to Gce, only MetC (not full-length Met) can interact with Ftz-F1 in the absence of JH. We propose that the described differences result from the distinct tertiary structure and accessibility of binding sites in the full-length Met/Gce. Moreover, we hypothesize that each interacting partner can force disordered MetC and GceC to change the structure in a partner-specific manner. The observed interactions seem to determine the subcellular localization of Met/Gce by forcing their translocation between the nucleus and the cytoplasm, which may affect the activity of the proteins. The presented differences between Met and Gce can be crucial for their functional differentiation during D. melanogaster development and indicate Gce as a more universal and more active paralog. It is consistent with the theory indicating gce as an ancestor gene.

Juvenile Hormone Membrane Signaling Enhances its Intracellular Signaling Through Phosphorylation of Met and Hsp83

Juvenile hormone (JH) regulates insect development and reproduction through both intracellular and membrane signaling, and the two pathways might crosstalk with each other. Recent studies have reported that JH membrane signaling induces phosphorylation of the JH intracellular receptor Met, thus enhancing its transcriptional activity. To gain more insights into JH-induced Met phosphorylation, we here performed phosphoproteomics to identify potential phosphorylation sites of Met and its paralog Germ-cell expressed (Gce) in Drosophila Kc cells. In vitro experiments demonstrate that JH-induced phosphorylation sites in the basic helix-loop-helix (bHLH) domain, but not in the Per-Arnt-Sim-B (PAS-B) domain, are required for maximization of Met transcriptional activity. Moreover, phosphoproteomics analysis reveale that JH also induces the phosphorylation of Hsp83, a chaperone protein involved in JH-activated Met nuclear import. The JH-induced Hsp83 phosphorylation at S219 facilitates Hsp83-Met binding, thus promoting Met nuclear import and its transcription. By using proteomics, subcellular distribution, and co-immunoprecipitation approaches, we further characterized 14-3-3 proteins as negative regulators of Met nuclear import through physical interaction with Hsp83. These results show that JH membrane signaling induces phosphorylation of the key components in JH intracellular signaling, such as Met and Hsp83, and consequently facilitating JH intracellular signaling.

Juvenile Hormone Studies in Drosophila melanogaster

In the field of insect endocrinology, juvenile hormone (JH) is one of the most wondrous entomological terms. As a unique sesquiterpenoid hormone produced and released by the endocrine gland, corpus allatum (CA), JH is a critical regulator in multiple developmental and physiological processes, such as metamorphosis, reproduction, and behavior. Benefited from the precise genetic interventions and simplicity, the fruit fly, Drosophila melanogaster, is an indispensable model in JH studies. This review is aimed to present the regulatory factors on JH biosynthesis and an overview of the regulatory roles of JH in Drosophila. The future directions of JH studies are also discussed, and a few hot spots are highlighted.

Purification of an insect juvenile hormone receptor complex enables insights into its post-translational phosphorylation

Juvenile hormone (JH) plays vital roles in insect reproduction, development, and in many aspects of physiology. JH primarily acts at the gene-regulatory level through interaction with an intracellular receptor (JH receptor [JHR]), a ligand-activated complex of transcription factors consisting of the JH-binding protein methoprene-tolerant (MET) and its partner taiman (TAI). Initial studies indicated significance of post-transcriptional phosphorylation, subunit assembly, and nucleocytoplasmic transport of JHR in JH signaling. However, our knowledge of JHR regulation at the protein level remains rudimentary, partly because of the difficulty of obtaining purified and functional JHR proteins. Here, we present a method for high-yield expression and purification of JHR complexes from two insect species, the beetle T. castaneum and the mosquito Aedes aegypti. Recombinant JHR subunits from each species were coexpressed in an insect cell line using a baculovirus system. MET–TAI complexes were purified through affinity chromatography and anion exchange columns to yield proteins capable of binding both the hormonal ligand (JH III) and DNA bearing cognate JH-response elements. We further examined the beetle JHR complex in greater detail. Biochemical analyses and MS confirmed that T. castaneum JHR was a 1:1 heterodimer consisting of MET and Taiman proteins, stabilized by the JHR agonist ligand methoprene. Phosphoproteomics uncovered multiple phosphorylation sites in the MET protein, some of which were induced by methoprene treatment. Finally, we report a functional bipartite nuclear localization signal, straddled by phosphorylated residues, within the disordered C-terminal region of MET. Our present characterization of the recombinant JHR is an initial step toward understanding JHR structure and function.

On the roles of intrinsically disordered proteins and regions in cell communication and signaling

For proteins, the sequence → structure → function paradigm applies primarily to enzymes, transmembrane proteins, and signaling domains. This paradigm is not universal, but rather, in addition to structured proteins, intrinsically disordered proteins and regions (IDPs and IDRs) also carry out crucial biological functions. For these proteins, the sequence → IDP/IDR ensemble → function paradigm applies primarily to signaling and regulatory proteins and regions. Often, in order to carry out function, IDPs or IDRs cooperatively interact, either intra- or inter-molecularly, with structured proteins or other IDPs or intermolecularly with nucleic acids. In this IDP/IDR thematic collection published in Cell Communication and Signaling, thirteen articles are presented that describe IDP/IDR signaling molecules from a variety of organisms from humans to fruit flies and tardigrades ("water bears") and that describe how these proteins and regions contribute to the function and regulation of cell signaling. Collectively, these papers exhibit the diverse roles of disorder in responding to a wide range of signals as to orchestrate an array of organismal processes. They also show that disorder contributes to signaling in a broad spectrum of species, ranging from micro-organisms to plants and animals.