Download MendeleyA Beta-Alanine Catabolism Pathway Containing a Highly Promiscuous Omega-Transaminase in the 12-Aminododecanate-Degrading Pseudomonas Sp. Strain Aac.
Wilding, M., Peat, T.S., Newman, J., Scott, C.(2016) Appl Environ Microbiol 82: 3846
- PubMed: 27107110
- DOI: https://doi.org/10.1128/AEM.00665-16
- Primary Citation of Related Structures:
4UHM, 4UHN, 4UHO - PubMed Abstract:
We previously isolated the transaminase KES23458 from Pseudomonas sp. strain AAC as a promising biocatalyst for the production of 12-aminododecanoic acid, a constituent building block of nylon-12. Here, we report the subsequent characterization of this transaminase. It exhibits activity with a broad substrate range which includes α-, β-, and ω-amino acids, as well as α,ω-diamines and a number of other industrially relevant compounds. It is therefore a prospective candidate for the biosynthesis of a range of polyamide monomers. The crystal structure of KES23458 revealed that the protein forms a dimer containing a large active site pocket and unusual phosphorylated histidine residues. To infer the physiological role of the transaminase, we expressed, purified, and characterized a dehydrogenase from the same operon, KES23460. Unlike the transaminase, the dehydrogenase was shown to be quite selective, catalyzing the oxidation of malonic acid semialdehyde, formed from β-alanine transamination via KES23458. In keeping with previous reports, the dehydrogenase was shown to catalyze both a coenzyme A (CoA)-dependent reaction to form acetyl-CoA and a significantly slower CoA-independent reaction to form acetate. These findings support the original functional assignment of KES23458 as a β-alanine transaminase. However, a seemingly well-adapted active site and promiscuity toward unnatural compounds, such as 12-aminododecanoic acid, suggest that this enzyme could perform multiple functions for Pseudomonas sp. strain AAC.
Organizational Affiliation:
CSIRO Land and Water, Black Mountain, Canberra, Australian Capital Territory, Australia.
