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A novel meso-Diaminopimelate dehydrogenase from Symbiobacterium thermophilum: overexpression, characterization, and potential for D-amino acid synthesis.

ABSTRACT: meso-Diaminopimelate dehydrogenase (meso-DAPDH) is an NADP(+)-dependent enzyme which catalyzes the reversible oxidative deamination on the d-configuration of meso-2,6-diaminopimelate to produce l-2-amino-6-oxopimelate. In this study, the gene encoding a meso-diaminopimelate dehydrogenase from Symbiobacterium thermophilum was cloned and expressed in Escherichia coli. In addition to the native substrate meso-2,6-diaminopimelate, the purified enzyme also showed activity toward d-alanine, d-valine, and d-lysine. This enzyme catalyzed the reductive amination of 2-keto acids such as pyruvic acid to generate d-amino acids in up to 99% conversion and 99% enantiomeric excess. Since meso-diaminopimelate dehydrogenases are known to be specific to meso-2,6-diaminopimelate, this is a unique wild-type meso-diaminopimelate dehydrogenase with a more relaxed substrate specificity and potential for d-amino acid synthesis. The enzyme is the most stable meso-diaminopimelate dehydrogenase reported to now. Two amino acid residues (F146 and M152) in the substrate binding sites of S. thermophilum meso-DAPDH different from the sequences of other known meso-DAPDHs were replaced with the conserved amino acids in other meso-DAPDHs, and assay of wild-type and mutant enzyme activities revealed that F146 and M152 are not critical in determining the enzyme's substrate specificity. The high thermostability and relaxed substrate profile of S. thermophilum meso-DAPDH warrant it as an excellent starting enzyme for creating effective d-amino acid dehydrogenases by protein engineering.

SUBMITTER: Gao X

PROVIDER: S-EPMC3502910 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature

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A novel meso-Diaminopimelate dehydrogenase from Symbiobacterium thermophilum: overexpression, characterization, and potential for D-amino acid synthesis.

Gao Xiuzhen X Chen Xi X Liu Weidong W Feng Jinhui J Wu Qiaqing Q Hua Ling L Zhu Dunming D

Applied and environmental microbiology 20120928 24

meso-Diaminopimelate dehydrogenase (meso-DAPDH) is an NADP(+)-dependent enzyme which catalyzes the reversible oxidative deamination on the d-configuration of meso-2,6-diaminopimelate to produce l-2-amino-6-oxopimelate. In this study, the gene encoding a meso-diaminopimelate dehydrogenase from Symbiobacterium thermophilum was cloned and expressed in Escherichia coli. In addition to the native substrate meso-2,6-diaminopimelate, the purified enzyme also showed activity toward d-alanine, d-valine, ...[more]

PMID: 23023754

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Project description:meso-Diaminopimelate dehydrogenase (meso-DAPDH) from Symbiobacterium thermophilum (StDAPDH) is the first member of the meso-DAPDH family known to catalyze the asymmetric reductive amination of 2-keto acids to produce d-amino acids. It is important to understand the catalytic mechanisms of StDAPDH and other enzymes in this family. In this study, based on an evolutionary analysis and examination of catalytic activity, the meso-DAPDH enzymes can be divided into two types. Type I showed highly preferable activity toward meso-diaminopimelate (meso-DAP), and type II exhibited obviously reversible amination activity with a broad substrate spectrum. StDAPDH belongs to type II. A quaternary structure analysis revealed that insertions/deletions (indels) and a loss of quaternary structure resulted in divergence among members of the meso-DAPDH family. A structure alignment of StDAPDH with a representative of type I, the meso-DAPDH from Corynebacterium glutamicum (CgDAPDH), indicated that they had the same folding. Based on sequence and conservation analyses, two amino acid residues of StDAPDH, R35 and R71, were found to be highly conserved within type II while also distinct from each other between the subtypes. Site mutagenesis studies identified R71 as a substrate preference-related residue of StDAPDH, which may serve as an indicator of the amination preference of type II. These results deepen the present understanding of the meso-DAPDH family and provide a solid foundation for the discovery and engineering of meso-DAPDH for d-amino acid biosynthesis.IMPORTANCE The l-form of amino acids is typically more abundant than the d-form. However, the d-form has many important pharmaceutical applications. meso-Diaminopimelate dehydrogenase (meso-DAPDH) from Symbiobacterium thermophilum (StDAPDH) was the first member of meso-DAPDH known to catalyze the amination of 2-keto acids to produce d-amino acids. Accordingly, we analyzed the evolution of meso-DAPDH proteins and found that they form two groups, i.e., type I proteins, which show high preference toward meso-diaminopimelate (meso-DAP), and type II proteins, which show a broad substrate spectrum. We examined the differences in sequence, ternary structure, and quaternary structure to determine the mechanisms underlying the functional differences between the type I and type II lineages. These results will facilitate the identification of additional meso-DAPDHs and may provide guidance to protein engineering studies for d-amino acid biosynthesis.

Dataset Information

A novel meso-Diaminopimelate dehydrogenase from Symbiobacterium thermophilum: overexpression, characterization, and potential for D-amino acid synthesis.

Publications

A novel meso-Diaminopimelate dehydrogenase from Symbiobacterium thermophilum: overexpression, characterization, and potential for D-amino acid synthesis.

Similar Datasets

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