Lysosomes break down various biomolecules and spinster is one of the major efflux carriers removing degradation products from lysosomal lumen to keep it in healthy size and proper function.Although it is well establis...Lysosomes break down various biomolecules and spinster is one of the major efflux carriers removing degradation products from lysosomal lumen to keep it in healthy size and proper function.Although it is well established that a dysfunctional spinster will cause enlarged lysosomes and in turn lead to developmental defects and abnormal behavior in animals,little was known about the transportation mechanism and substrate specificity of spinster.Here,we report a crystal structure of spinster homolog from Hyphomonas neptunium,HnSPNS,in its inward-facing conformation with and without substrate bound.HnSPNS is crystallized in a monomer and a substrate-binding cavity was formed in the center of its transmembrane helices.A blob of electron density corresponding to its substrate was found in the cavity near a conserved residue,R42,which is locked in position by the interactions with conserved residues E129 and R122.Our results suggest that human spinster serves as a transporter translocating negativelycharged lipophilic small molecules and E129 might serve as a switch to control the conformational change via its protonation-deprotonation cycle.展开更多
Lipid droplets, which are conserved across almost all species, are cytoplasmic organelles used to store neutral lipids. Identification of lipid droplet regulators will be conducive to resolving obesity and other fat-a...Lipid droplets, which are conserved across almost all species, are cytoplasmic organelles used to store neutral lipids. Identification of lipid droplet regulators will be conducive to resolving obesity and other fat-associated diseases. In this paper, we selected 11 candidates that might be associated with lipid metabolism in Caenorhabditis elegans . Using a BODIPY 493/503-based flow cytometry screen, 6 negative and 3 positive regulators of fat content were identified. We selected one negative regulator of lipid content, C13C4.5 , for future study. C13C4.5 was mainly expressed in the worm intestine. We found that this gene was important for maintaining the metabolism of lipid droplets. Biochemical results revealed that 50% of triacylglycerol (TAG) was lost in C13C4.5 knockout worms. Stimulated Raman scattering (SRS) signals in C13C4.5 mutants showed only 49.6% of the fat content in the proximal intestinal region and 86.3% in the distal intestinal region compared with wild type animals. The mean values of lipid droplet size and intensity in C13C4.5 knockout animals were found to be significantly decreased compared with those in wild type worms. The LMP-1-labeled membrane structures in worm intestines were also enlarged in C13C4.5 mutant animals. Finally, fertility defects were found in C13C4.5 ( ok2087 ) mutants. Taken together, these results indicate that C13C4.5 may regulate the fertility of C. elegans by changing the size and fat content of lipid droplets by interfering with lysosomal morphology and function.展开更多
基金supported by the National Key Research and Development Program of China (2017YFC1001303 and 2018YFC1004704)NSFC-CAS Joint Fund for Research Based on Large-Scale Scientific Facilities (U1632132)+1 种基金NSFC General Program (31670849)SHIPM-pi fund (JY201804) from Shanghai Institute of Precision Medicine, Ninth People’s Hospital Shanghai Jiao Tong University School of Medicine
文摘Lysosomes break down various biomolecules and spinster is one of the major efflux carriers removing degradation products from lysosomal lumen to keep it in healthy size and proper function.Although it is well established that a dysfunctional spinster will cause enlarged lysosomes and in turn lead to developmental defects and abnormal behavior in animals,little was known about the transportation mechanism and substrate specificity of spinster.Here,we report a crystal structure of spinster homolog from Hyphomonas neptunium,HnSPNS,in its inward-facing conformation with and without substrate bound.HnSPNS is crystallized in a monomer and a substrate-binding cavity was formed in the center of its transmembrane helices.A blob of electron density corresponding to its substrate was found in the cavity near a conserved residue,R42,which is locked in position by the interactions with conserved residues E129 and R122.Our results suggest that human spinster serves as a transporter translocating negativelycharged lipophilic small molecules and E129 might serve as a switch to control the conformational change via its protonation-deprotonation cycle.
基金support from the National Basic Research Program(973 Program)(Nos.2013CB910103 and 2010CB912303)the National Natural Science Foundation of China(Grant Nos.31170818 and 31270910)the project from the Chinese Academy of Sciences(KSCX2-EW-Q-11).
文摘Lipid droplets, which are conserved across almost all species, are cytoplasmic organelles used to store neutral lipids. Identification of lipid droplet regulators will be conducive to resolving obesity and other fat-associated diseases. In this paper, we selected 11 candidates that might be associated with lipid metabolism in Caenorhabditis elegans . Using a BODIPY 493/503-based flow cytometry screen, 6 negative and 3 positive regulators of fat content were identified. We selected one negative regulator of lipid content, C13C4.5 , for future study. C13C4.5 was mainly expressed in the worm intestine. We found that this gene was important for maintaining the metabolism of lipid droplets. Biochemical results revealed that 50% of triacylglycerol (TAG) was lost in C13C4.5 knockout worms. Stimulated Raman scattering (SRS) signals in C13C4.5 mutants showed only 49.6% of the fat content in the proximal intestinal region and 86.3% in the distal intestinal region compared with wild type animals. The mean values of lipid droplet size and intensity in C13C4.5 knockout animals were found to be significantly decreased compared with those in wild type worms. The LMP-1-labeled membrane structures in worm intestines were also enlarged in C13C4.5 mutant animals. Finally, fertility defects were found in C13C4.5 ( ok2087 ) mutants. Taken together, these results indicate that C13C4.5 may regulate the fertility of C. elegans by changing the size and fat content of lipid droplets by interfering with lysosomal morphology and function.
