Macroautophagy (hereafter autophagy) is essential for cells to respond to nutrient stress by delivering cytosolic contents to vacuoles for degradation via the formation of a multi-layer vesicle named autophagosome. A set of autophagy-related (ATG) regulators are recruited to the phagophore assembly site for the initiation of phagophore, as well as its expansion and closure and subsequent delivery into the vacuole. However, it remains elusive that how the phagophore assembly is regulated under different stress conditions.
View Article and Find Full Text PDFEukaryotic uL11 contains a conserved MPPKFDP motif at the N-terminus that is not found in archaeal and bacterial homologs. Here, we determined the solution structure of human uL11 by NMR spectroscopy and characterized its backbone dynamics by 15N-1H relaxation experiments. We showed that these N-terminal residues are unstructured and flexible.
View Article and Find Full Text PDFIn selective macroautophagy/autophagy, cargo receptors are recruited to the forming autophagosome by interacting with Atg8 (autophagy-related 8)-family proteins and facilitate the selective sequestration of specific cargoes for autophagic degradation. In addition, Atg8 interacts with a number of adaptors essential for autophagosome biogenesis, including ATG and non-ATG proteins. The majority of these adaptors and receptors are characterized by an Atg8-family interacting motif (AIM) for binding to Atg8.
View Article and Find Full Text PDFThe lateral stalk of ribosomes constitutes the GTPase-associated center and is responsible for recruiting translation factors to the ribosomes. The eukaryotic stalk contains a P-complex, in which one molecule of uL10 (formerly known as P0) protein binds two copies of P1/P2 heterodimers. Unlike bacterial uL10, eukaryotic uL10 has an extended protuberant (uL10ext) domain inserted into the N-terminal RNA-binding domain.
View Article and Find Full Text PDFRibosome-inactivating proteins (RIP) are RNA N-glycosidases that inactivate ribosomes by specifically depurinating a conserved adenine residue at the α-sarcin/ricin loop of 28S rRNA. Recent studies have pointed to the involvement of the C-terminal domain of the eukaryotic stalk proteins in facilitating the toxic action of RIPs. This review highlights how structural studies of eukaryotic stalk proteins provide insights into the recruitment of RIPs to the ribosomes.
View Article and Find Full Text PDFLateral ribosomal stalk is responsible for binding and recruiting translation factors during protein synthesis. The eukaryotic stalk consists of one P0 protein with two copies of P1•P2 heterodimers to form a P0(P1•P2)₂ pentameric P-complex. Here, we have solved the structure of full-length P1•P2 by nuclear magnetic resonance spectroscopy.
View Article and Find Full Text PDFThe lateral ribosomal stalk is responsible for the kingdom-specific binding of translation factors and activation of GTP hydrolysis during protein synthesis. The eukaryotic stalk is composed of three acidic ribosomal proteins P0, P1 and P2. P0 binds two copies of P1/P2 hetero-dimers to form a pentameric P-complex.
View Article and Find Full Text PDFThe lateral stalk of ribosome is responsible for kingdom-specific binding of translation factors and activation of GTP hydrolysis that drives protein synthesis. In eukaryotes, the stalk is composed of acidic ribosomal proteins P0, P1 and P2 that constitute a pentameric P-complex in 1: 2: 2 ratio. We have determined the solution structure of the N-terminal dimerization domain of human P2 (NTD-P2), which provides insights into the structural organization of the eukaryotic stalk.
View Article and Find Full Text PDFTrichosanthin (TCS) is a type I ribosome-inactivating protein that inactivates ribosome by enzymatically depurinating the A(4324) at the alpha-sarcin/ricin loop of 28S rRNA. We have shown in this and previous studies that TCS interacts with human acidic ribosomal proteins P0, P1 and P2, which constitute the lateral stalk of eukaryotic ribosome. Deletion mutagenesis showed that TCS interacts with the C-terminal tail of P2, the sequences of which are conserved in P0, P1 and P2.
View Article and Find Full Text PDFTrichosanthin (TCS), a ribosome-inactivating protein extracted from the root tuber of Chinese medicinal herb Trichosanthes kirilowii Maximowicz, has multiple pharmacological properties including abortifacient, anti-tumor and anti-HIV. It is traditionally used to induce abortion but its antigenicity and short plasma half-life have limited the repeated clinical administration. In this review, work to locating antigenic sites and prolonging plasma half-life are discussed.
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