Biochemical characterization of a recombinant plant aldehyde dehydrogenase 7 from Pisum sativum (PsALDH7)

David Kopečný, Martina Tylichová, Tomáš Andree, Jan Frömmel and Marek Šebela

Department of Biochemistry and Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc, Czech Republic

D¹-Piperideine-6-carboxylate dehydrogenase (P6CDH), also named α-aminoadipic semialdehyde dehydrogenase, antiquitin or simply aldehyde dehydrogenase 7 (ALDH7) represents a member of the ALDH7 family within the ALDH protein superfamily. Antiquitin's name (in Latin antiquusmeans old) is derived from the supposed high age of the respective coding gene. Human and plant ALDH7 proteins show roughly 60% identity in amino acids despite the evident evolutionary distance occurring between both organisms. Such a high degree of sequence similarity between species often indicates an essential and functionally conserved role within the cell. Human antiquitin was found to metabolize a wide range of aliphatic aldehydes, aromatic aldehydes and betaine aldehyde but it is mainly connected with lysine metabolism and mediates the conversion of α-aminoadipic semialdehyde (α-AASA) to α-aminoadipate. Mutation in human ALDH7A1 gene results in the accumulation of P6C in plasma that inactivates pyridoxal 5´-phosphate, an essential cofactor for many enzymatic reactions. The physiological function of plant antiquitin is believed to be related to a general stress response but no detailed data exist on the enzyme structure and substrate specificity. The gene coding for pea antiquitin (PsALDH7, GenBank accession number X54359) was cloned into a pCDFDuet vector and expressed in T7 E. coli cells. The final protein of 522 amino acids (55 kDa) carried an N-terminal 6xHis-tag and was purified on HIS-Select cobalt affinity gel. Protein identity was verified by MALDI-TOF peptide mass fingerprinting. The enzyme utilizes NAD⁺ but not NADP⁺ as a coenzyme and prefers α-AASA to other aliphatic and aromatic aldehydes.

This work was supported by grants 522/08/0555 from the Czech Science Foundation and grant, MSM 6198959215 from the Ministry of Education, Youth and Sports of the Czech Republic and PrF_2010_024 from the Faculty of Science, Palacký University in Olomouc.