ABSTRACT
The SorC family of transcriptional regulators plays a crucial role in controlling the carbohydrate metabolism and quorum sensing. We employed an integrative approach combining X-ray crystallography and cryo-electron microscopy to investigate architecture and functional mechanism of two prototypical representatives of two sub-classes of the SorC family: DeoR and CggR from Bacillus subtilis. Despite possessing distinct DNA-binding domains, both proteins form similar tetrameric assemblies when bound to their respective DNA operators. Structural analysis elucidates the process by which the CggR-regulated gapA operon is derepressed through the action of two effectors: fructose-1,6-bisphosphate and newly confirmed dihydroxyacetone phosphate. Our findings provide the first comprehensive understanding of the DNA binding mechanism of the SorC-family proteins, shedding new light on their functional characteristics.
Subject(s)
Bacillus subtilis , Bacterial Proteins , Cryoelectron Microscopy , Models, Molecular , Repressor Proteins , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Bacterial Proteins/genetics , Crystallography, X-Ray , Bacillus subtilis/genetics , Bacillus subtilis/metabolism , Repressor Proteins/chemistry , Repressor Proteins/metabolism , Repressor Proteins/genetics , Protein Binding , Protein Multimerization , DNA/chemistry , DNA/metabolism , Binding Sites , Gene Expression Regulation, Bacterial , DNA, Bacterial/metabolism , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , DNA-Binding Proteins/chemistry , DNA-Binding Proteins/metabolism , DNA-Binding Proteins/genetics , Operon/genetics , FructosediphosphatesABSTRACT
Long chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD/MTPD) and medium chain acyl-CoA dehydrogenase deficiency (MCADD) were included in the expanded neonatal screening program (ENBS) in Czechia in 2009, allowing for the presymptomatic diagnosis and nutritional management of these patients. The aim of our study was to assess the nationwide impact of ENBS on clinical outcome. This retrospective study analysed acute events and chronic complications and their severity in pre-ENBS and post-ENBS cohorts. In total, 28 children (12 before, 16 after ENBS) were diagnosed with LCHADD/MTPD (incidence 0.8/100,000 before and 1.2/100,000 after ENBS). In the subgroup detected by ENBS, a significantly longer interval from birth to first acute encephalopathy was observed. In addition, improvement in neuropathy and cardiomyopathy (although statistically non-significant) was demonstrated in the post-ENBS subgroup. In the MCADD cohort, we included 69 patients (15 before, 54 after ENBS). The estimated incidence rose from 0.7/100,000 before to 4.3/100,000 after ENBS. We confirmed a significant decrease in the number of episodes of acute encephalopathy and lower proportion of intellectual disability after ENBS (p < 0.0001). The genotype-phenotype correlations suggest a new association between homozygosity for the c.1528C > G variant and more severe heart involvement in LCHADD patients.
Subject(s)
Acyl-CoA Dehydrogenase/deficiency , Cardiomyopathies/diet therapy , Cardiomyopathies/diagnosis , Lipid Metabolism, Inborn Errors/diet therapy , Lipid Metabolism, Inborn Errors/diagnosis , Mitochondrial Myopathies/diet therapy , Mitochondrial Myopathies/diagnosis , Mitochondrial Trifunctional Protein/deficiency , Neonatal Screening/methods , Nervous System Diseases/diet therapy , Nervous System Diseases/diagnosis , Rhabdomyolysis/diet therapy , Rhabdomyolysis/diagnosis , 3-Hydroxyacyl CoA Dehydrogenases/deficiency , Cardiomyopathies/epidemiology , Carnitine/analogs & derivatives , Carnitine/blood , Child , Child, Preschool , Czech Republic/epidemiology , Female , Humans , Incidence , Infant , Infant, Newborn , Lipid Metabolism, Inborn Errors/epidemiology , Male , Metabolism, Inborn Errors/diagnosis , Mitochondrial Myopathies/epidemiology , Nervous System Diseases/epidemiology , Outcome Assessment, Health Care , Retrospective Studies , Rhabdomyolysis/epidemiology , Severity of Illness IndexABSTRACT
BACKGROUND: ALG3-CDG is a rare autosomal recessive disease. It is characterized by deficiency of alpha-1,3-mannosyltransferase caused by pathogenic variants in the ALG3 gene. Patients manifest with severe neurologic, cardiac, musculoskeletal and ophthalmic phenotype in combination with dysmorphic features, and almost half of them die before or during the neonatal period. CASE PRESENTATION: A 23 months-old girl presented with severe developmental delay, epilepsy, cortical atrophy, cerebellar vermis hypoplasia and ocular impairment. Facial dysmorphism, clubfeet and multiple joint contractures were observed already at birth. Transferrin isoelectric focusing revealed a type 1 pattern. Funduscopy showed hypopigmentation and optic disc pallor. Profound retinal ganglion cell loss and inner retinal layer thinning was documented on spectral-domain optical coherence tomography imaging. The presence of optic nerve hypoplasia was also supported by magnetic resonance imaging. A gene panel based next-generation sequencing and subsequent Sanger sequencing identified compound heterozygosity for two novel variants c.116del p.(Pro39Argfs*40) and c.1060 C > T p.(Arg354Cys) in ALG3. CONCLUSIONS: Our study expands the spectrum of pathogenic variants identified in ALG3. Thirty-three variants in 43 subjects with ALG3-CDG have been reported. Literature review shows that visual impairment in ALG3-CDG is most commonly linked to optic nerve hypoplasia.
