title: Molecular basis for the catalytic inactivity of a naturally occurring near-null variant of human ALOX15.
abstract: Mammalian lipoxygenases belong to a family of lipid-peroxidizing enzymes, which have been implicated in cardiovascular, hyperproliferative and neurodegenerative diseases. Here we report that a naturally occurring mutation in the hALOX15 gene leads to expression of a catalytically near-null enzyme variant (hGly422Glu). The inactivity may be related to severe misfolding of the enzyme protein, which was concluded from CD-spectra as well as from thermal and chemical stability assays. In silico mutagenesis experiments suggest that most mutations at hGly422 have the potential to induce sterical clash, which might be considered a reason for protein misfolding. hGly422 is conserved among ALOX5, ALOX12 and ALOX15 isoforms and corresponding hALOX12 and hALOX5 mutants also exhibited a reduced catalytic activity. Interestingly, in the hALOX5 Gly429Glu mutants the reaction specificity of arachidonic acid oxygenation was shifted from 5S- to 8S- and 12R-H(p)ETE formation. Taken together, our data indicate that the conserved glycine is of functional importance for these enzyme variants and most mutants at this position lose catalytic activity.
authors: Institute of Biochemistry, University Medicine Berlin-Charité, Charitéplatz 1, D-10117 Berlin, Germany. Electronic address: thomas.horn@charite.de.
authors: Thomas
authors: T
authors: Horn
authors: Igor
authors: I
authors: Ivanov
authors: Almerinda
authors: A
authors: Di Venere
authors: Kumar Reddy
authors: KR
authors: Kakularam
authors: Pallu
authors: P
authors: Reddanna
authors: Melanie L
authors: ML
authors: Conrad
authors: Constanze
authors: C
authors: Richter
authors: Patrick
authors: P
authors: Scheerer
authors: Hartmut
authors: H
authors: Kuhn
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001093:Arachidonate 15-Lipoxygenase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D017124:Conserved Sequence; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005973:Glutamine / Q000737:chemistry* / Q000235:genetics; D005998:Glycine / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000737:chemistry* / Q000378:metabolism; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D017510:Protein Folding; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013816:Thermodynamics
chemical_list: D006893:Hydroxyeicosatetraenoic Acids; D007527:Isoenzymes; D011994:Recombinant Proteins; D005973:Glutamine; C515716:ALOX15 protein, human; D001093:Arachidonate 15-Lipoxygenase; D005998:Glycine
keywords: (5Z,8Z,10E,14Z)-12-hydroperoxyeicosa-5,8,10,14-tetraenoic acid; (5Z,8Z,11Z,13E)-15-hydroperoxyeicosa-5,8,11,13-tetraenoic acid; (5Z,9E,11Z,14Z)-8-hydroperoxyicosa-5,9,11,14-tetraenoic acid; (9Z,11E,13S)-13-hydroperoxyoctadeca-9,11-dienoic acid; 12-H(p)ETE; 13-H(p)ODE; 15-H(p)ETE; 8-H(p)ETE; ALOX; ALOX15; ALOX15 gene variation; HETE; HpETE; IPTG; Isopropyl-β-d-thiogalactopyranoside; LOXs; Lipid peroxidation; Lipoxygenase; Misfolding; UTR; arachidonate lipoxygenase; hydroperoxyeicosatetraenoic acid; hydroxyeicosatetraenoic acid; lipoxygenases; untranslated region