Limits...
A gatekeeper helix determines the substrate specificity of Sjögren-Larsson Syndrome enzyme fatty aldehyde dehydrogenase.

Keller MA, Zander U, Fuchs JE, Kreutz C, Watschinger K, Mueller T, Golderer G, Liedl KR, Ralser M, Kräutler B, Werner ER, Marquez JA - Nat Commun (2014)

Bottom Line: Here, we present the crystallographic structure of human FALDH, the first model of a membrane-associated aldehyde dehydrogenase.The gatekeeper feature is conserved across membrane-associated aldehyde dehydrogenases.Finally, we provide insight into the previously elusive molecular basis of SLS-causing mutations.

View Article: PubMed Central - PubMed

Affiliation: 1] Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Innrain 80-82, 6020 Innsbruck, Austria [2] Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, 80 Tennis court Rd, Cambridge CB2 1GA, UK.

ABSTRACT
Mutations in the gene coding for membrane-bound fatty aldehyde dehydrogenase (FALDH) lead to toxic accumulation of lipid species and development of the Sjögren-Larsson Syndrome (SLS), a rare disorder characterized by skin defects and mental retardation. Here, we present the crystallographic structure of human FALDH, the first model of a membrane-associated aldehyde dehydrogenase. The dimeric FALDH displays a previously unrecognized element in its C-terminal region, a 'gatekeeper' helix, which extends over the adjacent subunit, controlling the access to the substrate cavity and helping orientate both substrate cavities towards the membrane surface for efficient substrate transit between membranes and catalytic site. Activity assays demonstrate that the gatekeeper helix is important for directing the substrate specificity of FALDH towards long-chain fatty aldehydes. The gatekeeper feature is conserved across membrane-associated aldehyde dehydrogenases. Finally, we provide insight into the previously elusive molecular basis of SLS-causing mutations.

No MeSH data available.


Related in: MedlinePlus

Structure of human FALDH.(a) FALDH is a symmetrical homodimer with a large dimerization interface. One subunit is shown in cartoon representations (green), the other as surface model (grey). Each dimer exhibits two active sites (catalytic side chains are shown in red). (b) The FALDH secondary structure (blue, β-sheets; red, α-helices): a central plane of beta sheets (β1–5 of each dimer) and two staggered, spiral-like alignment (β 6–14) that are enveloped by alpha helices (α 1–15). α16+17 are arranged around the substrate entry funnel of the respective other momomer. (c) The domain structure of FALDH includes a NAD-binding domain (green residues 1–79 and 103–208), a catalytic domain (red residues 209–419) and a C-terminal oligomerization domain (blue residues 82–102 and 420–443).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4109017&req=5

f2: Structure of human FALDH.(a) FALDH is a symmetrical homodimer with a large dimerization interface. One subunit is shown in cartoon representations (green), the other as surface model (grey). Each dimer exhibits two active sites (catalytic side chains are shown in red). (b) The FALDH secondary structure (blue, β-sheets; red, α-helices): a central plane of beta sheets (β1–5 of each dimer) and two staggered, spiral-like alignment (β 6–14) that are enveloped by alpha helices (α 1–15). α16+17 are arranged around the substrate entry funnel of the respective other momomer. (c) The domain structure of FALDH includes a NAD-binding domain (green residues 1–79 and 103–208), a catalytic domain (red residues 209–419) and a C-terminal oligomerization domain (blue residues 82–102 and 420–443).

Mentions: FALDH crystals containing amino acids 1–460 belong to the space group P 212121 and diffracted up to a resolution of 2.1 Å. Initial phases were obtained by molecular replacement using the human class 3 aldehyde dehydrogenase ALDH3A1 (3SZA16) as search model. The final model contains two chains of FALDH in the asymmetric unit and was refined to an Rwork of 19.96% and an Rfree of 22.26% (see Table 1). All amino acids present in the expression construct, including amino acid 1–460 of the human FALDH sequence, were modelled for Chain A. Conversely, in chain B, the residues 458–460 showed weak electron density, indicating that they are not well-ordered and hence were not included in the model. For an illustration of a typical electron density map, see Supplementary Fig. 1. Both subunits adopt very similar symmetrical, homodimeric structure and conformations (r.m.s.d. overall atoms=0.212 Å) (Fig. 2).


A gatekeeper helix determines the substrate specificity of Sjögren-Larsson Syndrome enzyme fatty aldehyde dehydrogenase.

Keller MA, Zander U, Fuchs JE, Kreutz C, Watschinger K, Mueller T, Golderer G, Liedl KR, Ralser M, Kräutler B, Werner ER, Marquez JA - Nat Commun (2014)

Structure of human FALDH.(a) FALDH is a symmetrical homodimer with a large dimerization interface. One subunit is shown in cartoon representations (green), the other as surface model (grey). Each dimer exhibits two active sites (catalytic side chains are shown in red). (b) The FALDH secondary structure (blue, β-sheets; red, α-helices): a central plane of beta sheets (β1–5 of each dimer) and two staggered, spiral-like alignment (β 6–14) that are enveloped by alpha helices (α 1–15). α16+17 are arranged around the substrate entry funnel of the respective other momomer. (c) The domain structure of FALDH includes a NAD-binding domain (green residues 1–79 and 103–208), a catalytic domain (red residues 209–419) and a C-terminal oligomerization domain (blue residues 82–102 and 420–443).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109017&req=5

f2: Structure of human FALDH.(a) FALDH is a symmetrical homodimer with a large dimerization interface. One subunit is shown in cartoon representations (green), the other as surface model (grey). Each dimer exhibits two active sites (catalytic side chains are shown in red). (b) The FALDH secondary structure (blue, β-sheets; red, α-helices): a central plane of beta sheets (β1–5 of each dimer) and two staggered, spiral-like alignment (β 6–14) that are enveloped by alpha helices (α 1–15). α16+17 are arranged around the substrate entry funnel of the respective other momomer. (c) The domain structure of FALDH includes a NAD-binding domain (green residues 1–79 and 103–208), a catalytic domain (red residues 209–419) and a C-terminal oligomerization domain (blue residues 82–102 and 420–443).
Mentions: FALDH crystals containing amino acids 1–460 belong to the space group P 212121 and diffracted up to a resolution of 2.1 Å. Initial phases were obtained by molecular replacement using the human class 3 aldehyde dehydrogenase ALDH3A1 (3SZA16) as search model. The final model contains two chains of FALDH in the asymmetric unit and was refined to an Rwork of 19.96% and an Rfree of 22.26% (see Table 1). All amino acids present in the expression construct, including amino acid 1–460 of the human FALDH sequence, were modelled for Chain A. Conversely, in chain B, the residues 458–460 showed weak electron density, indicating that they are not well-ordered and hence were not included in the model. For an illustration of a typical electron density map, see Supplementary Fig. 1. Both subunits adopt very similar symmetrical, homodimeric structure and conformations (r.m.s.d. overall atoms=0.212 Å) (Fig. 2).

Bottom Line: Here, we present the crystallographic structure of human FALDH, the first model of a membrane-associated aldehyde dehydrogenase.The gatekeeper feature is conserved across membrane-associated aldehyde dehydrogenases.Finally, we provide insight into the previously elusive molecular basis of SLS-causing mutations.

View Article: PubMed Central - PubMed

Affiliation: 1] Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Innrain 80-82, 6020 Innsbruck, Austria [2] Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, 80 Tennis court Rd, Cambridge CB2 1GA, UK.

ABSTRACT
Mutations in the gene coding for membrane-bound fatty aldehyde dehydrogenase (FALDH) lead to toxic accumulation of lipid species and development of the Sjögren-Larsson Syndrome (SLS), a rare disorder characterized by skin defects and mental retardation. Here, we present the crystallographic structure of human FALDH, the first model of a membrane-associated aldehyde dehydrogenase. The dimeric FALDH displays a previously unrecognized element in its C-terminal region, a 'gatekeeper' helix, which extends over the adjacent subunit, controlling the access to the substrate cavity and helping orientate both substrate cavities towards the membrane surface for efficient substrate transit between membranes and catalytic site. Activity assays demonstrate that the gatekeeper helix is important for directing the substrate specificity of FALDH towards long-chain fatty aldehydes. The gatekeeper feature is conserved across membrane-associated aldehyde dehydrogenases. Finally, we provide insight into the previously elusive molecular basis of SLS-causing mutations.

No MeSH data available.


Related in: MedlinePlus