Genotype-Phenotype Dissociation in Two Taiwanese Children with Molybdenum Cofactor Deficiency Caused by MOCS2 Mutation

Background To describe the genotype-phenotype dissociation in two Taiwanese patients with molybdenum cofactor deficiency (MoCoD) caused by MOCS2 gene mutations. Patient Description Patient 1 exhibited early-onset neurological symptoms soon after birth, followed by subsequent myoclonic seizures and movement disorder. The brain magnetic resonance imaging (MRI) showed diffuse brain injury with cystic encephalomalacia along with bilateral globus pallidi involvement, hypoplasia of corpus callosum, and cerebellar atrophy. Patient 2 had a mild phenotype with prominent movement disorder after intercurrent illness, and the brain MRI showed selective injury of the bilateral globus pallidi and the cerebellum. Both patients had markedly low levels of plasma uric acid and harbored the same MOCS2 homozygous c.16C > T mutation. Patient 1 showed chronic regression of developmental milestones and died of respiratory failure at the age of 8 years, whereas patient 2 demonstrated improvement in motor function. Conclusion Genotype-phenotype dissociation could be noted in patients with MoCoD due to MOCS2 mutation. Patients with neonatal seizures, developmental delay, movement disorder, and motor regression after an illness, as well as focal or bilateral involvement of the globus pallidi on the neuroimages, should undergo biochemical testing of plasma uric acid. A pronounced plasma uric acid level is a good indicator of MoCoD. Early diagnosis can allow early provision of adequate genetic counseling.

Engineering of molybdenum-cofactor-dependent nitrate assimilation in Yarrowia lipolytica

ABSTRACT Engineering a new metabolic function in a microbial host can be limited by the availability of the relevant cofactor. For instance, in Yarrowia lipolytica, the expression of a functional nitrate reductase is precluded by the absence of molybdenum cofactor (Moco) biosynthesis. In this study, we demonstrated that the Ogataea parapolymorpha Moco biosynthesis pathway combined with the expression of a high affinity molybdate transporter could lead to the synthesis of Moco in Y. lipolytica. The functionality of Moco was demonstrated by expression of an active Moco-dependent nitrate assimilation pathway from the same yeast donor, O. parapolymorpha. In addition to 11 heterologous genes, fast growth on nitrate required adaptive laboratory evolution which, resulted in up to 100-fold increase in nitrate reductase activity and in up to 4-fold increase in growth rate, reaching 0.13h-1. Genome sequencing of evolved isolates revealed the presence of a limited number of non-synonymous mutations or small insertions/deletions in annotated coding sequences. This study that builds up on a previous work establishing Moco synthesis in S. cerevisiae demonstrated that the Moco pathway could be successfully transferred in very distant yeasts and, potentially, to any other genera, which would enable the expression of new enzyme families and expand the nutrient range used by industrial yeasts.

Expanding the Phenotype of Molybdenum Cofactor Deficiency in Neonates: Report of Two Cases

Molybdenum cofactor deficiency (MoCD) is a rare neurometabolic disorder characterized by intractable seizures, progressive microcephaly, tone abnormalities, facial dysmorphism, and feeding difficulties in the neonatal period. We present two different neonatal cases of MoCD with atypical presentations which could have been easily missed. One is a preterm baby admitted with features of sepsis, poor perfusion, and seizures who later developed tone abnormalities and feeding difficulty. The second is a term baby who presented with stridor, respiratory distress, and metabolic acidosis followed by intractable seizures and encephalopathy. Both babies had characteristic radiological and biochemical findings, and genome sequencing identified mutations in MOCS2 and MOCS1 genes, respectively. MoCD presenting as hypoxic-ischemic encephalopathy and cerebral palsy are well described, but its presentation in preterm with “sepsis-like features with drug-responsive seizures” in the early newborn period is not described, and can also cause unnecessary delay in the diagnosis. Its clinical presentation with “stridor, respiratory distress, and metabolic acidosis” is also described for the first time in literature.

Identification and Computational Analysis of 3D-Structure Of MOCS1

Cyclic pyranopterin monophosphate (cPMP) is one of the most stable intermediates in Molybdenum cofactor (MoCo) biosynthetic pathway. In humans, synthesis of cPMP from Guanosine triphosphate (GTP) requires functional genes i.e. Molybdenum Cofactor Synthesis-1 (MOCS1) genes that contains for two catalytic proteins MOCS1A and MOCS1B. Importance of MOCS1A and MOCS1B for biosynthesis of MoCo reveals from the fact that its deficiency leads to MoCo type A deficiency. As there is no structure available for MOCS1 genes in the literature, tertiary structure of MOCS1 genes were investigated in this research via threading or folds recognition method by i-TASSER and validation was done using ERRAT, Verify3D and Ramachandran plots. Binding sites were predicted and validated. Docking of MOCS1A with GTP and MOCS1B with 3, 8 dihydroguanosine was done using Autodock via PyRx. Apart from this, highly confident mutations were also predicted using SIFT and polyphen2 that can alter the structure and function of MOCS1 gene.

Differential expression of molybdenum cofactor synthesis 1 in cancers of the breast.

Breast cancer affects women at relatively high frequency (1). We mined published microarray datasets (2, 3) to determine in an unbiased fashion and at the systems level genes most differentially expressed in the primary tumors of patients with breast cancer. We report here significant differential expression of the gene encoding molybdenum cofactor synthesis 1, MOCS1, when comparing primary tumors of the breast to the tissue of origin, the normal breast. MOCS1 mRNA was present at significantly lower quantities in tumors of the breast as compared to normal breast tissue. Analysis of human survival data revealed that expression of MOCS1 in primary tumors of the breast was correlated with overall survival in patients with basal subtype cancer, demonstrating a relationship between primary tumor expression of a differentially expressed gene and patient survival outcomes influenced by molecular subtype. MOCS1 may be of relevance to initiation, maintenance or progression of cancers of the female breast.

Case Report: Compound Heterozygous Variants in MOCS3 Identified in a Chinese Infant With Molybdenum Cofactor Deficiency

Background: The molybdenum cofactor (Moco) deficiency in humans results in the inactivity of molybdenum-dependent enzymes and is caused by pathogenic variants in MOCS1 (Molybdenum cofactor synthesis 1), MOCS2 (Molybdenum cofactor synthesis 2), and GPHN (Gephyrin). These genes along with MOCS3 (Molybdenum cofactor synthesis 3) are involved in Moco biosynthesis and providing cofactors to Moco-dependent enzymes. Until now, there was no study to confirm that MOCS3 is a causative gene of Moco deficiency.Methods: Detailed clinical information was collected in the pedigree. The Whole-exome sequencing (WES) accompanied with Sanger sequencing validation were performed.Results: We described the clinical presentations of an infant, born to a non-consanguineous healthy family, diagnosed as having MOCS3 variants caused Moco deficiency and showing typical features of Moco deficiency including severe neurologic symptoms and cystic encephalomalacia in the brain MRI, resulting in neonatal death. Compound heterozygous variants in the MOCS3 gene were identified by WES. Positive sulfite and decreased levels of uric acid in plasma and urine were detected.Conclusion: To our knowledge, this is the first case of MOCS3 variants causing Moco deficiency. Our study may contribute to genetic diagnosis of Moco deficiency and future genetic counseling.