Search results for "Biogenesis"
showing 10 items of 150 documents
The Proteome and Lipidome of Synechocystis sp. PCC 6803 Cells Grown under Light-Activated Heterotrophic Conditions*
2015
Cyanobacteria are photoautotrophic prokaryotes with a plant-like photosynthetic machinery. Because of their short generation times, the ease of their genetic manipulation, and the limited size of their genome and proteome, cyanobacteria are popular model organisms for photosynthetic research. Although the principal mechanisms of photosynthesis are well-known, much less is known about the biogenesis of the thylakoid membrane, hosting the components of the photosynthetic, and respiratory electron transport chain in cyanobacteria. Here we present a detailed proteome analysis of the important model and host organism Synechocystis sp. PCC 6803 under light-activated heterotrophic growth condition…
Cholesterol binds to synaptophysin and is required for biogenesis of synaptic vesicles.
1999
Here, to study lipid-protein interactions that contribute to the biogenesis of regulated secretory vesicles, we have developed new approaches by which to label proteins in vivo, using photoactivatable cholesterol and glycerophospholipids. We identify synaptophysin as a major specifically cholesterol-binding protein in PC12 cells and brain synaptic vesicles. Limited cholesterol depletion, which has little effect on total endocytic activity, blocks the biogenesis of synaptic-like microvesicles (SLMVs) from the plasma membrane. We propose that specific interactions between cholesterol and SLMV membrane proteins, such as synaptophysin, contribute to both the segregation of SLMV membrane constit…
Extracellular vesicles shuffling intercellular messages: for good or for bad
2015
The release of extracellular vesicles (EVs) is a highly conserved process exploited by diverse organisms as a mode of intercellular communication. Vesicles of sizes ranging from 30 to 1000. nm, or even larger, are generated by blebbing of the plasma membrane (microvesicles) or formed in multivesicular endosomes (MVEs) to be secreted by exocytosis as exosomes. Exosomes, microvesicles and other EVs contain membrane and cytosolic components that include proteins, lipids and RNAs, a composition that differs related to their site of biogenesis. Several mechanisms are involved in vesicle formation at the plasma membrane or in endosomes, which is reflected in their heterogeneity, size and composit…
γ2-Adaptin is functioning in the late endosomal sorting pathway and interacts with ESCRT-I and -III subunits.
2010
Abstractγ2-Adaptin is a clathrin adaptor-related protein with unclear physiological function. Previous studies indicated that γ2-adaptin might act within the multivesicular body (MVB) protein-sorting pathway that is central to receptor down-regulation, lysosome biogenesis, and budding of enveloped viruses. Here, we have analyzed the effects of excess and deficit γ2-adaptin on exogenous and endogenous MVB cargoes and on the MVB machinery itself. Foreign cargoes, like retroviral Gags, are entrapped by overexpressed γ2-adaptin in detergent-insoluble polymers and blocked in budding. When viral budding involves MVB/endosomal structures, excess γ2-adaptin acts by accelerating lysosomal Gag destru…
Evolution of Prokaryote-Animal Symbiosis from a Genomics Perspective
2010
Symbioses involving prokaryotes living in close relationship with eukaryotic cells have been widely studied from a genomic perspective, especially in the case of insects. In the process toward host accommodation, symbionts experience major genetic and phenotypic changes that can be detected in comparison with free-living relatives. But, as expected, several scenarios allowed the evolution of symbiotic associations, from the first stages of free-living bacteria, through secondary and facultative symbiosis, towards the final point of obligate primary endosymbiosis. Particular relevance has the association formed by the coexistence of several symbionts into a given host. A summary of findings …
Binding and/or hydrolysis of purine‐based nucleotides is not required for IM30 ring formation
2021
IM30, the inner membrane-associated protein of 30 kDa, is conserved in cyanobacteria and chloroplasts. Although its exact physiological function is still mysterious, IM30 is clearly essential for thylakoid membrane biogenesis and/or dynamics. Recently, a cryptic IM30 GTPase activity has been reported, albeit thus far no physiological function has been attributed to this. Yet, it is still possible that GTP binding/hydrolysis affects formation of the prototypical large homo-oligomeric IM30 ring and rod structures. Here, we show that the Synechocystis sp. PCC 6803 IM30 protein in fact is an NTPase that hydrolyzes GTP and ATP, but not CTP or UTP, with about identical rates. While IM30 forms lar…
Hsp90 dictates viral sequence space by balancing the evolutionary tradeoffs between protein stability, aggregation and translation rate
2017
AbstractAcquisition of mutations is central to evolution but the detrimental effects of most mutations on protein folding and stability limit protein evolvability. Molecular chaperones, which suppress aggregation and facilitate polypeptide folding, are proposed to promote sequence diversification by buffering destabilizing mutations. However, whether and how chaperones directly control protein evolution remains poorly understood. Here, we examine the effect of reducing the activity of the key eukaryotic chaperone Hsp90 on poliovirus evolution. Contrary to predictions of a buffering model, inhibiting Hsp90 increases population sequence diversity and promotes accumulation of mutations reducin…
Styryl-lactones from Goniothalamus species— A review
1999
Thirty-one bioactive styryl-lactones, with six different basic skeletons, have been isolated from Goniothalamus species. Aspects of their isolation, structural elucidation, biogenesis and biological activity are reviewed. Copyright © 1999 John Wiley & Sons, Ltd.
Lipid Droplets in the Pathogenesis of Hereditary Spastic Paraplegia
2021
Hereditary spastic paraplegias (HSPs) are genetically heterogeneous conditions caused by the progressive dying back of the longest axons in the central nervous system, the corticospinal axons. A wealth of data in the last decade has unraveled disturbances of lipid droplet (LD) biogenesis, maturation, turnover and contact sites in cellular and animal models with perturbed expression and function of HSP proteins. As ubiquitous organelles that segregate neutral lipid into a phospholipid monolayer, LDs are at the cross-road of several processes including lipid metabolism and trafficking, energy homeostasis, and stress signaling cascades. However, their role in brain cells, especially in neurons…
Structure and function of the vacuolar Ccc1/VIT1 family of iron transporters and its regulation in fungi
2020
Iron is an essential micronutrient for most living beings since it participates as a redox active cofactor in many biological processes including cellular respiration, lipid biosynthesis, DNA replication and repair, and ribosome biogenesis and recycling. However, when present in excess, iron can participate in Fenton reactions and generate reactive oxygen species that damage cells at the level of proteins, lipids and nucleic acids. Organisms have developed different molecular strategies to protect themselves against the harmful effects of high concentrations of iron. In the case of fungi and plants, detoxification mainly occurs by importing cytosolic iron into the vacuole through the Ccc1/V…