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Brain : a Journal of Neurology Mar 2022Subcellular membrane systems are highly enriched in dolichol, whose role in organelle homeostasis and endosomal-lysosomal pathway remains largely unclear besides being...
Subcellular membrane systems are highly enriched in dolichol, whose role in organelle homeostasis and endosomal-lysosomal pathway remains largely unclear besides being involved in protein glycosylation. DHDDS encodes for the catalytic subunit (DHDDS) of the enzyme cis-prenyltransferase (cis-PTase), involved in dolichol biosynthesis and dolichol-dependent protein glycosylation in the endoplasmic reticulum. An autosomal recessive form of retinitis pigmentosa (retinitis pigmentosa 59) has been associated with a recurrent DHDDS variant. Moreover, two recurring de novo substitutions were detected in a few cases presenting with neurodevelopmental disorder, epilepsy and movement disorder. We evaluated a large cohort of patients (n = 25) with de novo pathogenic variants in DHDDS and provided the first systematic description of the clinical features and long-term outcome of this new neurodevelopmental and neurodegenerative disorder. The functional impact of the identified variants was explored by yeast complementation system and enzymatic assay. Patients presented during infancy or childhood with a variable association of neurodevelopmental disorder, generalized epilepsy, action myoclonus/cortical tremor and ataxia. Later in the disease course, they experienced a slow neurological decline with the emergence of hyperkinetic and/or hypokinetic movement disorder, cognitive deterioration and psychiatric disturbances. Storage of lipidic material and altered lysosomes were detected in myelinated fibres and fibroblasts, suggesting a dysfunction of the lysosomal enzymatic scavenger machinery. Serum glycoprotein hypoglycosylation was not detected and, in contrast to retinitis pigmentosa and other congenital disorders of glycosylation involving dolichol metabolism, the urinary dolichol D18/D19 ratio was normal. Mapping the disease-causing variants into the protein structure revealed that most of them clustered around the active site of the DHDDS subunit. Functional studies using yeast complementation assay and in vitro activity measurements confirmed that these changes affected the catalytic activity of the cis-PTase and showed growth defect in yeast complementation system as compared with the wild-type enzyme and retinitis pigmentosa-associated protein. In conclusion, we characterized a distinctive neurodegenerative disorder due to de novo DHDDS variants, which clinically belongs to the spectrum of genetic progressive encephalopathies with myoclonus. Clinical and biochemical data from this cohort depicted a condition at the intersection of congenital disorders of glycosylation and inherited storage diseases with several features akin to of progressive myoclonus epilepsy such as neuronal ceroid lipofuscinosis and other lysosomal disorders.
Topics: Alkyl and Aryl Transferases; Child; Dolichols; Humans; Myoclonus; Neurodegenerative Diseases; Retinitis Pigmentosa
PubMed: 34382076
DOI: 10.1093/brain/awab299 -
Glycoconjugate Journal Jan 2013In the majority of congenital disorders of glycosylation, the assembly of the glycan precursor GlcNAc(2)Man(9)Glc(3) on the polyprenol carrier dolichyl-pyrophosphate is... (Review)
Review
In the majority of congenital disorders of glycosylation, the assembly of the glycan precursor GlcNAc(2)Man(9)Glc(3) on the polyprenol carrier dolichyl-pyrophosphate is compromised. Because N-linked glycosylation is essential to life, most types of congenital disorders of glycosylation represent partial losses of enzymatic activity. Consequently, increased availability of substrates along the glycosylation pathway can be beneficial to increase product formation by the compromised enzymes. Recently, we showed that increased dolichol availability and improved N-linked glycosylation can be achieved by inhibition of squalene biosynthesis. This review summarizes the current knowledge on the biosynthesis of dolichol-linked glycans with respect to deficiencies in N-linked glycosylation. Additionally, perspectives on therapeutic treatments targeting dolichol and dolichol-linked glycan biosynthesis are examined.
Topics: Carbohydrate Sequence; Congenital Disorders of Glycosylation; Dolichol Phosphates; Dolichols; Glycosylation; Humans; Polysaccharides
PubMed: 22717794
DOI: 10.1007/s10719-012-9417-y -
Bioscience, Biotechnology, and... Jun 2018The reduction pathway leading to the formation of dolichol was clarified in 2010 with the identification of SRD5A3, which is the polyprenol reductase. The finding... (Review)
Review
The reduction pathway leading to the formation of dolichol was clarified in 2010 with the identification of SRD5A3, which is the polyprenol reductase. The finding inspired us to reanalyze the length of the major chain of polyprenol and dolichol from several plant leaves, including mangrove plants, as well as from animal and fish livers by 2D-TLC. Polyprenol- and dolichol-derived metabolites such as polyprenylacetone and epoxydolichol were found together with rubber-like prenol. This review focuses on analyses of polyprenol and its derivatives, including recently found epoxypolyprenol and polyprenylacetone. Attention has also been paid to the chromatographic behavior of rubber-like prenol on TLC.
Topics: Animals; Chromatography, Thin Layer; Dolichols; Hemiterpenes; Liver; Pentanols; Plant Leaves
PubMed: 29297247
DOI: 10.1080/09168451.2017.1411775 -
Journal of Inherited Metabolic Disease Jan 2015Congenital disorders of glycosylation (CDG) comprise a group of inborn errors of metabolism with abnormal glycosylation of proteins and lipids. Patients with defective... (Review)
Review
Congenital disorders of glycosylation (CDG) comprise a group of inborn errors of metabolism with abnormal glycosylation of proteins and lipids. Patients with defective protein N-glycosylation are identified in routine metabolic screening via analysis of serum transferrin glycosylation. Defects in the assembly of the dolichol linked Glc(3)Man(9)GlcNAc(2) glycan and its transfer to proteins lead to the (partial) absence of complete glycans on proteins. These defects are called CDG-I and are located in the endoplasmic reticulum (ER) or cytoplasm. Defects in the subsequent processing of protein bound glycans result in the presence of truncated glycans on proteins. These defects are called CDG-II and the enzymes involved are located mainly in the Golgi apparatus. In recent years, human defects have been identified in dolichol biosynthesis genes within the group of CDG-I patients. This has increased interest in dolichol metabolism, has resulted in specific recognizable clinical symptoms in CDG-I and has offered new mechanistic insights in dolichol biosynthesis. We here review its biosynthetic pathways, the clinical and biochemical phenotypes in dolichol-related CDG defects, up to the formation of dolichyl-P-mannose (Dol-P-Man), and discuss existing evidence of regulatory networks in dolichol metabolism to provide an outlook on therapeutic strategies.
Topics: Animals; Congenital Disorders of Glycosylation; Cytoplasm; Dolichols; Endoplasmic Reticulum; Glycosylation; Golgi Apparatus; Humans; Mice; Oxidoreductases; Phenotype; Phosphotransferases (Alcohol Group Acceptor)
PubMed: 25270028
DOI: 10.1007/s10545-014-9760-1 -
Pathogens (Basel, Switzerland) Jan 2021-glycosylation has remained mostly unexplored in Piroplasmida, an order of tick-transmitted pathogens of veterinary and medical relevance. Analysis of 11 piroplasmid...
-glycosylation has remained mostly unexplored in Piroplasmida, an order of tick-transmitted pathogens of veterinary and medical relevance. Analysis of 11 piroplasmid genomes revealed three distinct scenarios regarding -glycosylation: sensu stricto (s.s.) species add one or two -acetylglucosamine (NAcGlc) molecules to proteins; and add (NAcGlc)-mannose, while and s.s. synthesize dolichol-P-P-NAcGlc and dolichol-P-P-(NAcGlc) without subsequent transfer to proteins. All piroplasmids possess the gene complement needed for the synthesis of the -glycosylation substrates, dolichol-P and sugar nucleotides. The oligosaccharyl transferase of species, and , is predicted to be composed of only two subunits, STT3 and Ost1. Occurrence of short -glycans in merozoites was experimentally demonstrated by fluorescence microscopy using a NAcGlc-specific lectin. In vitro growth of was significantly impaired by tunicamycin, an inhibitor of -glycosylation, indicating a relevant role for -glycosylation in this pathogen. Finally, genes coding for -glycosylation enzymes and substrate biosynthesis are transcribed in blood and tick stages, suggesting that this pathway is biologically relevant throughout the parasite life cycle. Elucidation of the role/s exerted by -glycans will increase our understanding of these successful parasites, for which improved control measures are needed.
PubMed: 33429911
DOI: 10.3390/pathogens10010050 -
Frontiers in Chemistry 2022is the etiological agent of human malaria, one of the most widespread diseases in tropical and subtropical regions. Drug resistance is one of the biggest problems in...
is the etiological agent of human malaria, one of the most widespread diseases in tropical and subtropical regions. Drug resistance is one of the biggest problems in controlling the disease, which leads to the need to discover new antimalarial compounds. One of the most promissory drugs purposed is fosmidomycin, an inhibitor of the biosynthesis of isoprene units by the methylerythritol 4-phosphate (MEP) pathway, which in some cases failed in clinical studies. Once formed, isoprene units are condensed to form longer structures such as farnesyl and geranylgeranyl pyrophosphate, which are necessary for Heme O and A formation, ubiquinone, and dolichyl phosphate biosynthesis as well as for protein isoprenylation. Even though the natural substrates of polyprenyl transferases and synthases are polyprenyl pyrophosphates, it was already demonstrated that isoprenoid alcohols (polyprenols) such as farnesol (FOH) and geranylgeraniol (GGOH) can rescue parasites from fosmidomycin. This study better investigated how this rescue phenomenon occurs by performing drug-rescue assays. Similarly, to FOH and GGOH, it was observed that phytol (POH), a 20-carbon plant isoprenoid, as well as unsaponifiable lipid extracts from foods rescue parasites from the antimalarial effect of fosmidomycin. Contrarily, neither dolichols nor nonaprenol rescue parasites from fosmidomycin. Considering this, here we characterized the transport of FOH, GGOH, and POH. Once incorporated, it was observed that these substances are phosphorylated, condensed into longer isoprenoid alcohols, and incorporated into proteins and dolichyl phosphates. Through proteomic and radiolabelling approaches, it was found that prenylated proteins are naturally attached to several isoprenoids, derived from GGOH, dolichol, and POH if exogenously added. Furthermore, the results suggest the presence of at least two promiscuous protein prenyltransferases in the parasite: one enzyme which can use FPP among other unidentified substrates and another enzyme that can use GGPP, phytyl pyrophosphate (PPP), and dolichols, among other substrates not identified here. Thus, further evidence was obtained for dolichols and other isoprenoid products attached to proteins. This study helps to better understand the apicoplast-targeting antimalarial mechanism of action and a novel post-translational modification of proteins in .
PubMed: 36531309
DOI: 10.3389/fchem.2022.1035548 -
Biochimica Et Biophysica Acta Sep 2009Dolichol phosphate is a lipid carrier embedded in the endoplasmic reticulum (ER) membrane essential for the synthesis of N-glycans, GPI-anchors and protein C- and... (Review)
Review
Dolichol phosphate is a lipid carrier embedded in the endoplasmic reticulum (ER) membrane essential for the synthesis of N-glycans, GPI-anchors and protein C- and O-mannosylation. The availability of dolichol phosphate on the cytosolic site of the ER is rate-limiting for N-glycosylation. The abundance of dolichol phosphate is influenced by its de novo synthesis and the recycling of dolichol phosphate from the luminal leaflet to the cytosolic leaflet of the ER. Enzymatic defects affecting the de novo synthesis and the recycling of dolichol phosphate result in glycosylation defects in yeast or cell culture models, and are expected to cause glycosylation disorders in humans termed congenital disorders of glycosylation (CDG). Currently only one disorder affecting the dolichol phosphate metabolism has been described. In CDG-Im, the final step of the de novo synthesis of dolichol phosphate catalyzed by the enzyme dolichol kinase is affected. The defect causes a severe phenotype with death in early infancy. The present review summarizes the biosynthesis of dolichol-phosphate and the recycling pathway with respect to possible defects of the dolichol phosphate metabolism causing glycosylation defects in humans.
Topics: Animals; CHO Cells; Cricetinae; Cricetulus; Dolichol Phosphates; Endoplasmic Reticulum; Glycosylation; Humans; Phosphotransferases (Alcohol Group Acceptor); Pyrophosphatases; Transferases
PubMed: 19419701
DOI: 10.1016/j.bbadis.2009.01.013 -
Biochimica Et Biophysica Acta.... Jun 2017N-glycosylation, a post-translational modification whereby glycans are covalently linked to select Asn residues of target proteins, occurs in all three domains of life.... (Review)
Review
N-glycosylation, a post-translational modification whereby glycans are covalently linked to select Asn residues of target proteins, occurs in all three domains of life. Across evolution, the N-linked glycans are initially assembled on phosphorylated cytoplasmically-oriented polyisoprenoids, with polyprenol (mainly C undecaprenol) fulfilling this role in Bacteria and dolichol assuming this function in Eukarya and Archaea. The eukaryal and archaeal versions of dolichol can, however, be distinguished on the basis of their length, degree of saturation and by other traits. As is true for many facets of their biology, Archaea, best known in their capacity as extremophiles, present unique approaches for synthesizing phosphodolichols. At the same time, general insight into the assembly and processing of glycan-bearing phosphodolichols has come from studies of the archaeal enzymes responsible. In this review, these and other aspects of archaeal phosphodolichol biology are addressed.
Topics: Archaea; Carbohydrates; Dolichol Phosphates; Glycosylation
PubMed: 28330764
DOI: 10.1016/j.bbalip.2017.03.005