Project description:A gene encoding a third alpha-galactosidase (AglB) from Aspergillus niger has been cloned and sequenced. The gene consists of an open reading frame of 1,750 bp containing six introns. The gene encodes a protein of 443 amino acids which contains a eukaryotic signal sequence of 16 amino acids and seven putative N-glycosylation sites. The mature protein has a calculated molecular mass of 48,835 Da and a predicted pI of 4.6. An alignment of the AglB amino acid sequence with those of other alpha-galactosidases revealed that it belongs to a subfamily of alpha-galactosidases that also includes A. niger AglA. A. niger AglC belongs to a different subfamily that consists mainly of prokaryotic alpha-galactosidases. The expression of aglA, aglB, aglC, and lacA, the latter of which encodes an A. niger beta-galactosidase, has been studied by using a number of monomeric, oligomeric, and polymeric compounds as growth substrates. Expression of aglA is only detected on galactose and galactose-containing oligomers and polymers. The aglB gene is expressed on all of the carbon sources tested, including glucose. Elevated expression was observed on xylan, which could be assigned to regulation via XlnR, the xylanolytic transcriptional activator. Expression of aglC was only observed on glucose, fructose, and combinations of glucose with xylose and galactose. High expression of lacA was detected on arabinose, xylose, xylan, and pectin. Similar to aglB, the expression on xylose and xylan can be assigned to regulation via XlnR. All four genes have distinct expression patterns which seem to mirror the natural substrates of the encoded proteins.
Project description:Chromosome level genome assembly and comparative genomics between three falcon species reveals a pattern of genome organization not typical for birds
Project description:Binding of a single-chain Fv antibody to Escherichia coli β-galactosidase (β-gal) is known to stabilize the enzyme and activate several inactive point mutants, historically called antibody-mediated enzyme formation mutants. To understand the nature of this activation, we have determined by electron cryo-microscopy the structure of the complex between β-gal and the antibody scFv13R4. Our structure localizes the scFv13R4 binding site to the crevice between domains 1 and 3 in each β-gal subunit. The mutations that scFv13R4 counteracts are located between the antibody binding site and the active site of β-gal, at one end of the TIM-barrel that forms domain 3 where the substrate lactose is hydrolyzed. The mode of binding suggests how scFv stabilizes both the active site of β-gal and the tetrameric state.
Project description:Beta (β)-galactosidase is a lysosomal enzyme that removes terminal galactose residues from glycolipids and glycoproteins. It is upregulated in, and used as a marker for, senescent cells. Microglia are brain macrophages implicated in neurodegeneration, and can upregulate β-galactosidase when senescent. We find that inflammatory activation of microglia induced by lipopolysaccharide results in translocation of β-galactosidase to the cell surface and release into the medium. Similarly, microglia in aged mouse brains appear to have more β-galactosidase on their surface. Addition of β-galactosidase to neuronal-glial cultures causes microglial activation and neuronal loss mediated by microglia. Inhibition of β-galactosidase in neuronal-glial cultures reduces inflammation and neuronal loss induced by lipopolysaccharide. Thus, activated microglia release β-galactosidase that promotes microglial-mediated neurodegeneration which is prevented by inhibition of β-galactosidase.