Role and structural characterization of plant aldehyde dehydrogenases from family 2 and family 7.
Aldehyde dehydrogenases (ALDHs) are responsible for oxidation of biogenic aldehyde intermediates as well as for cell detoxification of aldehydes generated during lipid peroxidation. So far, 13 ALDH families have been described in plants. In the present study, we provide a detailed biochemical characterization of plant ALDH2 and ALDH7 families by analysing maize and pea ALDH7 (ZmALDH7 and PsALDH7) and four maize cytosolic ALDH(cALDH)2 isoforms RF2C, RF2D, RF2E and RF2F [the first maize ALDH2 was discovered as a fertility restorer (RF2A)]. We report the crystal structures of ZmALDH7, RF2C and RF2F at high resolution. The ZmALDH7 structure shows that the three conserved residues Glu(120), Arg(300) and Thr(302) in the ALDH7 family are located in the substrate-binding site and are specific to this family. Our kinetic analysis demonstrates that α-aminoadipic semialdehyde, a lysine catabolism intermediate, is the preferred substrate for plant ALDH7. In contrast, aromatic aldehydes including benzaldehyde, anisaldehyde, cinnamaldehyde, coniferaldehyde and sinapaldehyde are the best substrates for cALDH2. In line with these results, the crystal structures of RF2C and RF2F reveal that their substrate-binding sites are similar and are formed by an aromatic cluster mainly composed of phenylalanine residues and several nonpolar residues. Gene expression studies indicate that the RF2C gene, which is strongly expressed in all organs, appears essential, suggesting that the crucial role of the enzyme would certainly be linked to the cell wall formation using aldehydes from phenylpropanoid pathway as substrates. Finally, plant ALDH7 may significantly contribute to osmoprotection because it oxidizes several aminoaldehydes leading to products known as osmolytes.
*Department of Protein Biochemistry and Proteomics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 11, Olomouc CZ-783 71, Czech Republic.
Radka
R
Končitíková
‡Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Avenue de la Terrasse, Gif-sur-Yvette 91198, France.
Armelle
A
Vigouroux
*Department of Protein Biochemistry and Proteomics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 11, Olomouc CZ-783 71, Czech Republic.
Martina
M
Kopečná
†Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, Olomouc CZ-783 71, Czech Republic.
Tomáš
T
Andree
§Centre of Plant Structural and Functional Genomics, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany, Šlechtitelů 31, Olomouc CZ-78371, Czech Republic.
Jan
J
Bartoš
*Department of Protein Biochemistry and Proteomics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 11, Olomouc CZ-783 71, Czech Republic.
Marek
M
Šebela
‡Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Avenue de la Terrasse, Gif-sur-Yvette 91198, France.
Solange
S
Moréra
*Department of Protein Biochemistry and Proteomics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 11, Olomouc CZ-783 71, Czech Republic.
David
D
Kopečný
D000444:Aldehyde Dehydrogenase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D020134:Catalytic Domain / Q000235:genetics; D018360:Crystallography, X-Ray; D020869:Gene Expression Profiling; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D018532:Pisum sativum / Q000201:enzymology / Q000235:genetics; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010944:Plants / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity; D003313:Zea mays / Q000201:enzymology / Q000235:genetics
D007527:Isoenzymes; D010940:Plant Proteins; D009243:NAD; D000444:Aldehyde Dehydrogenase