The aryl hydrocarbon receptor (AHR) and the AHR nuclear translocator (ARNT) constitute a heterodimeric basic helix-loop-helix-Per-ARNT-Sim (bHLH-PAS) domain containing transcription factor with ...central functions in development and cellular homeostasis. AHR is activated by xenobiotics, notably dioxin, as well as by exogenous and endogenous metabolites. Modulation of AHR activity holds promise for the treatment of diseases featuring altered cellular homeostasis, such as cancer or autoimmune disorders. Here, we present the crystal structure of a heterodimeric AHR:ARNT complex containing the PAS A and bHLH domain bound to its target DNA. The structure provides insights into the DNA binding mode of AHR and elucidates how stable dimerization of AHR:ARNT is achieved through sophisticated domain interplay via three specific interfaces. Using mutational analyses, we prove the relevance of the observed interfaces for AHR-mediated gene activation. Thus, our work establishes the structural basis of AHR assembly and DNA interaction and provides a template for targeted drug design.
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•Structure of an AHR:ARNT complex bound to DNA•Clarification of the DNA binding mode of the AHR:ARNT complex•A sophisticated domain assembly mediates dimerization of AHR and ARNT•AHR surface may offer specific sites for drug development
The aryl hydrocarbon receptor (AHR) and the AHR nuclear translocator (ARNT) form a heterodimeric basic helix-loop-helix-PER-ARNT SIM (PAS) domain containing transcription factor. Here, Schulte et al. report the crystal structure of the AHR-ARNT core complex bound to its target DNA.
The autophagy cargo receptor p62 facilitates the condensation of misfolded, ubiquitin-positive proteins and their degradation by autophagy, but the molecular mechanism of p62 signaling to the core ...autophagy machinery is unclear. Here, we show that disordered residues 326–380 of p62 directly interact with the C-terminal region (CTR) of FIP200. Crystal structure determination shows that the FIP200 CTR contains a dimeric globular domain that we designated the “Claw” for its shape. The interaction of p62 with FIP200 is mediated by a positively charged pocket in the Claw, enhanced by p62 phosphorylation, mutually exclusive with the binding of p62 to LC3B, and it promotes degradation of ubiquitinated cargo by autophagy. Furthermore, the recruitment of the FIP200 CTR slows the phase separation of ubiquitinated proteins by p62 in a reconstituted system. Our data provide the molecular basis for a crosstalk between cargo condensation and autophagosome formation.
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•p62 directly interacts with the FIP200 C-terminal domain•Structural studies reveal a claw shape of the conserved FIP200 C-terminal domain•p62-ubiquitin condensates recruit FIP200 via the Claw to promote their degradation•LC3B outcompetes FIP200 from p62, suggesting an inbuild directionality in the system
Turco et al. show that p62 interacts with the claw-shaped C-terminal domain of FIP200. This interaction is enhanced by p62 phosphorylation, mutually exclusive with the binding of p62 to LC3B, and promotes degradation of ubiquitinated cargo by autophagy. The recruitment of the FIP200 Claw slows the formation of p62-ubiquitin condensates in a reconstituted system.
The large GTPase dynamin is the first protein shown to catalyze membrane fission. Dynamin and its related proteins are essential to many cell functions, from endocytosis to organelle division and ...fusion, and it plays a critical role in many physiological functions such as synaptic transmission and muscle contraction. Research of the past three decades has focused on understanding how dynamin works. In this review, we present the basis for an emerging consensus on how dynamin functions. Three properties of dynamin are strongly supported by experimental data: first, dynamin oligomerizes into a helical polymer; second, dynamin oligomer constricts in the presence of GTP; and third, dynamin catalyzes membrane fission upon GTP hydrolysis. We present the two current models for fission, essentially diverging in how GTP energy is spent. We further discuss how future research might solve the remaining open questions presently under discussion.
This consensus review summarizes our current understanding of the function of the fission GTPase dynamin and highlights open questions in the field.
Lysine acetylation regulates the function of soluble proteins in vivo, yet it remains largely unexplored whether lysine acetylation regulates membrane protein function. Here, we use bioinformatics, ...biophysical analysis of recombinant proteins, live-cell fluorescent imaging and genetic manipulation of Drosophila to explore lysine acetylation in peripheral membrane proteins. Analysis of 50 peripheral membrane proteins harboring BAR, PX, C2, or EHD membrane-binding domains reveals that lysine acetylation predominates in membrane-interaction regions. Acetylation and acetylation-mimicking mutations in three test proteins, amphiphysin, EHD2, and synaptotagmin1, strongly reduce membrane binding affinity, attenuate membrane remodeling in vitro and alter subcellular localization. This effect is likely due to the loss of positive charge, which weakens interactions with negatively charged membranes. In Drosophila, acetylation-mimicking mutations of amphiphysin cause severe disruption of T-tubule organization and yield a flightless phenotype. Our data provide mechanistic insights into how lysine acetylation regulates membrane protein function, potentially impacting a plethora of membrane-related processes.
Hantaviruses are etiological agents of life-threatening hemorrhagic fever with renal syndrome and hantavirus cardiopulmonary syndrome. The nucleoprotein (N) of hantavirus is essential for viral ...transcription and replication, thus representing an attractive target for therapeutic intervention. We have determined the crystal structure of hantavirus N to 3.2 Å resolution. The structure reveals a two-lobed, mostly α-helical structure that is distantly related to that of orthobunyavirus Ns. A basic RNA binding pocket is located at the intersection between the two lobes. We provide evidence that oligomerization is mediated by amino- and C-terminal arms that bind to the adjacent monomers. Based on these findings, we suggest a model for the oligomeric ribonucleoprotein (RNP) complex. Our structure provides mechanistic insights into RNA encapsidation in the genus Hantavirus and constitutes a template for drug discovery efforts aimed at combating hantavirus infections.
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•Hantavirus nucleoprotein shows a unique bilobed architecture•The RNA binding site is located at the lobe intersection•Oligomerization is mediated by amino- and carboxy-terminal arms
Hantavirus is the causative agent of life-threatening hemorrhagic fever with renal syndrome. Olal and Daumke describe the crystal structure of the nucleoprotein of hantavirus and suggest a mechanism by which it oligomerizes and sequesters the viral RNA genome.
Dynamin is a mechanochemical GTPase that oligomerizes around the neck of clathrin-coated pits and catalyses vesicle scission in a GTP-hydrolysis-dependent manner. The molecular details of ...oligomerization and the mechanism of the mechanochemical coupling are currently unknown. Here we present the crystal structure of human dynamin 1 in the nucleotide-free state with a four-domain architecture comprising the GTPase domain, the bundle signalling element, the stalk and the pleckstrin homology domain. Dynamin 1 oligomerized in the crystals via the stalks, which assemble in a criss-cross fashion. The stalks further interact via conserved surfaces with the pleckstrin homology domain and the bundle signalling element of the neighbouring dynamin molecule. This intricate domain interaction rationalizes a number of disease-related mutations in dynamin 2 and suggests a structural model for the mechanochemical coupling that reconciles previous models of dynamin function.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
The heterotrimeric NatC complex, comprising the catalytic Naa30 and the two auxiliary subunits Naa35 and Naa38, co-translationally acetylates the N-termini of numerous eukaryotic target ...proteins. Despite its unique subunit composition, its essential role for many aspects of cellular function and its suggested involvement in disease, structure and mechanism of NatC have remained unknown. Here, we present the crystal structure of the
Saccharomyces cerevisiae
NatC complex, which exhibits a strikingly different architecture compared to previously described N-terminal acetyltransferase (NAT) complexes. Cofactor and ligand-bound structures reveal how the first four amino acids of cognate substrates are recognized at the Naa30–Naa35 interface. A sequence-specific, ligand-induced conformational change in Naa30 enables efficient acetylation. Based on detailed structure–function studies, we suggest a catalytic mechanism and identify a ribosome-binding patch in an elongated tip region of NatC. Our study reveals how NAT machineries have divergently evolved to N-terminally acetylate specific subsets of target proteins.
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