X-linked adrenoleukodystrophy: Clinical, biochemical and pathogenetic aspects

AbstractX-linked adrenoleukodystrophy (X-ALD) is a clinically heterogeneous disorder ranging from the severe childhood cerebral form to asymptomatic persons. The overall incidence is 1:16,800 including hemizygotes as well as heterozygotes. The principal molecular defect is due to inborn mutations in the ABCD1 gene encoding the adrenoleukodystrophy protein (ALDP), a transporter in the peroxisome membrane. ALDP is involved in the transport of substrates from the cytoplasm into the peroxisomal lumen. ALDP defects lead to characteristic accumulation of saturated very long-chain fatty acids, the diagnostic disease marker. The pathogenesis is unclear. Different molecular mechanisms seem to induce inflammatory demyelination, neurodegeneration and adrenocortical insufficiency involving the primary ABCD1 defect, environmental factors and modifier genes. Important information has been derived from the X-ALD mouse models; species differences however complicate the interpretation of results. So far, bone marrow transplantation is the only effective long-term treatment for childhood cerebral X-ALD, however, only when performed at an early-stage of disease. Urgently needed novel therapeutic strategies are under consideration ranging from dietary approaches to gene therapy

Amphritea atlantica gen. nov., sp. nov., a gammaproteobacterium from the Logatchev hydrothermal vent field

A novel Gram-negative, motile, aerobic rod-shaped bacterium was isolated from a Bathymodiolus sp. specimen collected from the Logatchev hydrothermal vent field at the Mid-Atlantic Ridge. The novel strain, M41(T), was catalase- and oxidase-positive and metabolised various carbohydrates and amino acids. It grew well in marine broth with an optimal growth temperature of 31 degrees C to 34 degrees C (range 4-40 degrees C and salinity requirement of 3% (range 0.3-9%). The pH range for growth was pH 4.6 to 9.5, with an optimum at pH 8.0. The predominant fatty acids were C-16: (1)omega 7c, C-16: 0 and C-18: 1 omega 7c. The DNA G + C content of strain M41(T) was 52.2 mol%. The 16S rRNA gene sequence was 94 % similar to that of the type strain of Oceanospirillum beijerinckii, the closest cultivated relative. Other related type strains were Oceanospirillum multiglobuliferum (93% gene sequence similarity), Neptunomonas naphthovorans (92%) and Marinobacterium jannaschii (92 %). According to phylogenetic analysis and physiological characteristics, it is suggested that strain M41(T) represents a new genus and novel species for which the name Amphritea atlantica gen. nov., sp. nov. is proposed. The type strain is M41(T) (= DSM 18887(T) = LMG 24143(T))

Kiloniella laminariae, gen. nov., sp. nov., a new alphaproteobacterium from the marine macroalga Laminaria saccharina

A novel alphaproteobacterium, strain LD81(T), was isolated from the marine macroalga. Laminaria saccharina. The bacterium is mesophilic and shows a typical marine growth response. It is a chemoheterotrophic aerobe with the potential for denitrification. Growth optima are 25 degrees C, pH 5.5 and 3% NaCl. Strain LD81(T) has a unique phylogenetic position, not fitting any of the known families of the Alphaproteobacteria. The 16S rRNA gene sequence revealed a distant relationship to species of several orders of the Alphaproteobacteria, with less than 90% sequence similarity. Phylogenetically, strain LD81(T) is related to the type strains of Terasakiella pusilla (88.4% 16S rRNA gene sequence similarity) and the three Thalassospira species (88.9-89.2%. It forms a cluster with these bacteria and a novel as-yet undescribed isolate (KOPRI 13522; 96.6% sequence similarity). Strain LD81(T) has a relatively low DNA G + C content (51.1 mol%) and, due to its distant phylogenetic position from all other alphaprotecibacteria, strain LD81(T) (=NCIMB 14374(T) =JCM 14845(T)) is considered as the type strain of a novel species within a new genus, for which the name Kiloniella laminariae gen. nov., sp. nov. is proposed. The genus Kiloniella represents the type of the new family Kiloniellaceae fam. nov. and order Kiloniellales ord. nov

Conserved targeting information in mammalian and fungal peroxisomal tail-anchored proteins

The targeting signals and mechanisms of soluble peroxisomal proteins are well understood, whereas less is known about the signals and targeting routes of peroxisomal membrane proteins (PMP). Pex15 and PEX26, tail-anchored proteins in yeast and mammals, respectively, exert a similar cellular function in the recruitment of AAA peroxins at the peroxisomal membrane. But despite their common role, Pex15 and PEX26 are neither homologs nor they are known to follow similar targeting principles. Here we show that Pex15 targets to peroxisomes in mammalian cells, and PEX26 reaches peroxisomes when expressed in yeast cells. In both proteins C-terminal targeting information is sufficient for correct sorting to the peroxisomal membrane. In yeast, PEX26 follows the pathway that also ensures correct targeting of Pex15: PEX26 enters the endoplasmic reticulum (ER) in a GET-dependent and Pex19-independent manner. Like in yeast, PEX26 enters the ER in mammalian cells, however, independently of GET/TRC40. These data show that conserved targeting information is employed in yeast and higher eukaryotes during the biogenesis of peroxisomal tail-anchored proteins

Conserved targeting information in mammalian and fungal peroxisomal tail-anchored proteins

The targeting signals and mechanisms of soluble peroxisomal proteins are well understood, whereas less is known about the signals and targeting routes of peroxisomal membrane proteins (PMP). Pex15 and PEX26, tail-anchored proteins in yeast and mammals, respectively, exert a similar cellular function in the recruitment of AAA peroxins at the peroxisomal membrane. But despite their common role, Pex15 and PEX26 are neither homologs nor they are known to follow similar targeting principles. Here we show that Pex15 targets to peroxisomes in mammalian cells, and PEX26 reaches peroxisomes when expressed in yeast cells. In both proteins C-terminal targeting information is sufficient for correct sorting to the peroxisomal membrane. In yeast, PEX26 follows the pathway that also ensures correct targeting of Pex15: PEX26 enters the endoplasmic reticulum (ER) in a GET-dependent and Pex19-independent manner. Like in yeast, PEX26 enters the ER in mammalian cells, however, independently of GET/TRC40. These data show that conserved targeting information is employed in yeast and higher eukaryotes during the biogenesis of peroxisomal tail-anchored proteins

Characterization of two common 5' polymorphisms in PEX1 and correlation to survival in PEX1 peroxisome biogenesis disorder patients

<p>Abstract</p> <p>Background</p> <p>Mutations in PEX1 are the most common primary cause of Zellweger syndrome. In addition to exonic mutations, deletions and splice site mutations two 5' polymorphisms at c.-137 and c.-53 with a potential influence on PEX1 protein levels have been described in the 5' untranslated region (UTR) of the <it>PEX1 </it>gene.</p> <p>Methods</p> <p>We used RACE and in silico promoter prediction analysis to study the 5' UTR of <it>PEX1</it>. We determined the distribution of <it>PEX1 </it>5' polymorphisms in a cohort of 30 Zellweger syndrome patients by standard DNA sequencing. 5' polymorphisms were analysed in relation to the two most common mutations in <it>PEX1 </it>and were incorporated into a novel genotype-phenotype analysis by correlation of three classes of <it>PEX1 </it>mutations with patient survival.</p> <p>Results</p> <p>We provide evidence that the polymorphism 137 bp upstream of the ATG codon is not part of the UTR, rendering it a promoter polymorphism. We show that the first, but not the second most common <it>PEX1 </it>mutation arose independently of a specific upstream polymorphic constellation. By genotype-phenotype analysis we identified patients with identical exonic mutation and identical 5' polymorphisms, but strongly differing survival.</p> <p>Conclusions</p> <p>Our study suggests that two different types of <it>PEX1 </it>5' polymorphisms have to be distinguished: a 5' UTR polymorphism at position c.-53 and a promoter polymorphism 137 bp upstream of the PEX1 start codon. Our results indicate that the exonic <it>PEX1 </it>mutation correlates with patient survival, but the two 5' polymorphisms analysed in this study do not have to be considered for diagnostic and/or prognostic purposes.</p

Levantilides A and B, 20-Membered Macrolides from a Micromonospora Strain Isolated from the Mediterranean Deep Sea Sediment

Two new 20-membered macrolides, levantilide A and B, were isolated from the Micromonospora strain M71-A77. Strain M71-A77 was recovered from an Eastern Mediterranean deep-sea sediment sample and revealed to produce the levantilides under in situ salinity of 38.6‰. The chemical structures of the levantilides were elucidated on the basis of different one- and two- dimensional NMR experiments. Levantilide A exhibits a moderate antiproliferative activity against several tumor cell lines

Structure of sulfamidase provides insight into the molecular pathology of mucopolysaccharidosis IIIA

Mucopolysaccharidosis type IIIA (Sanfilippo A syndrome), a fatal childhood-onset neurodegenerative disease with mild facial, visceral and skeletal abnormalities, is caused by an inherited deficiency of the enzyme N-sulfoglucosamine sulfohydrolase (SGSH; sulfamidase). More than 100 mutations in the SGSH gene have been found to reduce or eliminate its enzymatic activity. However, the molecular understanding of the effect of these mutations has been confined by a lack of structural data for this enzyme. Here, the crystal structure of glycosylated SGSH is presented at 2Å resolution. Despite the low sequence identity between this unique N-sulfatase and the group of O-sulfatases, they share a similar overall fold and active-site architecture, including a catalytic formylglycine, a divalent metal-binding site and a sulfate-binding site. However, a highly conserved lysine in O-sulfatases is replaced in SGSH by an arginine (Arg282) that is positioned to bind the N-linked sulfate substrate. The structure also provides insight into the diverse effects of pathogenic mutations on SGSH function in mucopolysaccharidosis type IIIA and convincing evidence for the molecular consequences of many missense mutations. Further, the molecular characterization of SGSH mutations will lay the groundwork for the development of structure-based drug design for this devastating neurodegenerative disorder. © 2014 International Union of Crystallography.This work was funded by the DFG. Partial support from DFG grant No. SH 14/5-1 is gratefully acknowledged (NSS). IU is grateful to the Spanish MEC and Generalitat de Catalunya for financial support (grants BFU2012-35367, IDC-20101173 and 2009SGR-1036)Peer Reviewe

Homozygous NMNAT2 mutation in sisters with polyneuropathy and erythromelalgia.

We identified a homozygous missense mutation in the gene encoding NAD synthesizing enzyme NMNAT2 in two siblings with childhood onset polyneuropathy with erythromelalgia. No additional homozygotes for this rare allele, which leads to amino acid substitution T94M, were present among the unaffected relatives tested or in the 60,000 exomes of the ExAC database. For axons to survive, axonal NMNAT2 activity has to be maintained above a threshold level but the T94M mutation confers a partial loss of function both in the ability of NMNAT2 to support axon survival and in its enzymatic properties. Electrophysiological tests and histological analysis of sural nerve biopsies in the patients were consistent with loss of distal sensory and motor axons. Thus, it is likely that NMNAT2 mutation causes this pain and axon loss phenotype making this the first disorder associated with mutation of a key regulator of Wallerian-like axon degeneration in humans. This supports indications from numerous animal studies that the Wallerian degeneration pathway is important in human disease and raises important questions about which other human phenotypes could be linked to this gene