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Structural insights into the production of 3-hydroxypropionic acid by aldehyde dehydrogenase from Azospirillum brasilense

View Article: PubMed Central - PubMed

ABSTRACT

3-Hydroxypropionic acid (3-HP) is an important platform chemical to be converted to acrylic acid and acrylamide. Aldehyde dehydrogenase (ALDH), an enzyme that catalyzes the reaction of 3-hydroxypropionaldehyde (3-HPA) to 3-HP, determines 3-HP production rate during the conversion of glycerol to 3-HP. To elucidate molecular mechanism of 3-HP production, we determined the first crystal structure of a 3-HP producing ALDH, α-ketoglutarate-semialdehyde dehydrogenase from Azospirillum basilensis (AbKGSADH), in its apo-form and in complex with NAD+. Although showing an overall structure similar to other ALDHs, the AbKGSADH enzyme had an optimal substrate binding site for accepting 3-HPA as a substrate. Molecular docking simulation of 3-HPA into the AbKGSADH structure revealed that the residues Asn159, Gln160 and Arg163 stabilize the aldehyde- and the hydroxyl-groups of 3-HPA through hydrogen bonds, and several hydrophobic residues, such as Phe156, Val286, Ile288, and Phe450, provide the optimal size and shape for 3-HPA binding. We also compared AbKGSADH with other reported 3-HP producing ALDHs for the crucial amino acid residues for enzyme catalysis and substrate binding, which provides structural implications on how these enzymes utilize 3-HPA as a substrate.

No MeSH data available.


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3-HP production pathway and amino acid sequence alignment of 3-HP producing ALDHs.(a) 3-HP production pathway. (b) Amino acid sequence alignment of eight reported 3-HP producing ALDHs. The secondary structure elements are drawn based on the structure of AbKGSADH. The catalytic residues of AbKGSADH are indicated by red colored triangles, and the residues involved in the binding of aldehyde- and hydroxyl-groups of 3-HPA are indicated by green colored triangles. The residues involved in the formation of hydrophobic pocket are indicated by blue colored triangles. The residues involved in the adenine ring and 2′-hydroxyl-group of NAD+ are indicated by orange colored residues, and the residues involved in the formation of pyrophosphate, ribose ring, and nicotinamide are indicated by purple colored triangles. Ab, Bs, Cn, Ec, Kp, and Sc are abbreviations of Azospirillum basilensis, Bacillus subtilis, Cupriavidus necator, Escherichia coli, Klebsiella pneumonia, and Saccharomyces cerevisiae, respectively.
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f1: 3-HP production pathway and amino acid sequence alignment of 3-HP producing ALDHs.(a) 3-HP production pathway. (b) Amino acid sequence alignment of eight reported 3-HP producing ALDHs. The secondary structure elements are drawn based on the structure of AbKGSADH. The catalytic residues of AbKGSADH are indicated by red colored triangles, and the residues involved in the binding of aldehyde- and hydroxyl-groups of 3-HPA are indicated by green colored triangles. The residues involved in the formation of hydrophobic pocket are indicated by blue colored triangles. The residues involved in the adenine ring and 2′-hydroxyl-group of NAD+ are indicated by orange colored residues, and the residues involved in the formation of pyrophosphate, ribose ring, and nicotinamide are indicated by purple colored triangles. Ab, Bs, Cn, Ec, Kp, and Sc are abbreviations of Azospirillum basilensis, Bacillus subtilis, Cupriavidus necator, Escherichia coli, Klebsiella pneumonia, and Saccharomyces cerevisiae, respectively.

Mentions: To date, two biosynthetic routes using glycerol or glucose as carbon substrate have been extensively studied for industrial production of 3-HP. With glucose as carbon source, 3-HP can be produced via malonyl-CoA or β-alanine456. With glycerol as substrate, glycerol is converted to 3-hydroxypropionaldehyde (3-HPA) by coenzyme B12-dependent glycerol dehydratase (DhaB) and 3-HPA is then converted to 3-HP by NAD+-dependent aldehyde dehydrogenases (ALDHs) (Fig. 1a)78. The route using glycerol as the carbon source is advantageous because the pathway is simple and cheap glycerol is abundantly available as a waste by product from biodiesel industry910111213.


Structural insights into the production of 3-hydroxypropionic acid by aldehyde dehydrogenase from Azospirillum brasilense
3-HP production pathway and amino acid sequence alignment of 3-HP producing ALDHs.(a) 3-HP production pathway. (b) Amino acid sequence alignment of eight reported 3-HP producing ALDHs. The secondary structure elements are drawn based on the structure of AbKGSADH. The catalytic residues of AbKGSADH are indicated by red colored triangles, and the residues involved in the binding of aldehyde- and hydroxyl-groups of 3-HPA are indicated by green colored triangles. The residues involved in the formation of hydrophobic pocket are indicated by blue colored triangles. The residues involved in the adenine ring and 2′-hydroxyl-group of NAD+ are indicated by orange colored residues, and the residues involved in the formation of pyrophosphate, ribose ring, and nicotinamide are indicated by purple colored triangles. Ab, Bs, Cn, Ec, Kp, and Sc are abbreviations of Azospirillum basilensis, Bacillus subtilis, Cupriavidus necator, Escherichia coli, Klebsiella pneumonia, and Saccharomyces cerevisiae, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5385487&req=5

f1: 3-HP production pathway and amino acid sequence alignment of 3-HP producing ALDHs.(a) 3-HP production pathway. (b) Amino acid sequence alignment of eight reported 3-HP producing ALDHs. The secondary structure elements are drawn based on the structure of AbKGSADH. The catalytic residues of AbKGSADH are indicated by red colored triangles, and the residues involved in the binding of aldehyde- and hydroxyl-groups of 3-HPA are indicated by green colored triangles. The residues involved in the formation of hydrophobic pocket are indicated by blue colored triangles. The residues involved in the adenine ring and 2′-hydroxyl-group of NAD+ are indicated by orange colored residues, and the residues involved in the formation of pyrophosphate, ribose ring, and nicotinamide are indicated by purple colored triangles. Ab, Bs, Cn, Ec, Kp, and Sc are abbreviations of Azospirillum basilensis, Bacillus subtilis, Cupriavidus necator, Escherichia coli, Klebsiella pneumonia, and Saccharomyces cerevisiae, respectively.
Mentions: To date, two biosynthetic routes using glycerol or glucose as carbon substrate have been extensively studied for industrial production of 3-HP. With glucose as carbon source, 3-HP can be produced via malonyl-CoA or β-alanine456. With glycerol as substrate, glycerol is converted to 3-hydroxypropionaldehyde (3-HPA) by coenzyme B12-dependent glycerol dehydratase (DhaB) and 3-HPA is then converted to 3-HP by NAD+-dependent aldehyde dehydrogenases (ALDHs) (Fig. 1a)78. The route using glycerol as the carbon source is advantageous because the pathway is simple and cheap glycerol is abundantly available as a waste by product from biodiesel industry910111213.

View Article: PubMed Central - PubMed

ABSTRACT

3-Hydroxypropionic acid (3-HP) is an important platform chemical to be converted to acrylic acid and acrylamide. Aldehyde dehydrogenase (ALDH), an enzyme that catalyzes the reaction of 3-hydroxypropionaldehyde (3-HPA) to 3-HP, determines 3-HP production rate during the conversion of glycerol to 3-HP. To elucidate molecular mechanism of 3-HP production, we determined the first crystal structure of a 3-HP producing ALDH, α-ketoglutarate-semialdehyde dehydrogenase from Azospirillum basilensis (AbKGSADH), in its apo-form and in complex with NAD+. Although showing an overall structure similar to other ALDHs, the AbKGSADH enzyme had an optimal substrate binding site for accepting 3-HPA as a substrate. Molecular docking simulation of 3-HPA into the AbKGSADH structure revealed that the residues Asn159, Gln160 and Arg163 stabilize the aldehyde- and the hydroxyl-groups of 3-HPA through hydrogen bonds, and several hydrophobic residues, such as Phe156, Val286, Ile288, and Phe450, provide the optimal size and shape for 3-HPA binding. We also compared AbKGSADH with other reported 3-HP producing ALDHs for the crucial amino acid residues for enzyme catalysis and substrate binding, which provides structural implications on how these enzymes utilize 3-HPA as a substrate.

No MeSH data available.


Related in: MedlinePlus