6SQ8

Structure of amide bond synthetase McbA from Marinactinospora thermotolerans

Summary for 6SQ8

• Entry DOI: 10.2210/pdb6sq8/pdb
• Descriptor: Fatty acid CoA ligase, 1-ethanoyl-9~{H}-pyrido[3,4-b]indole-3-carboxylic acid, ADENOSINE MONOPHOSPHATE, ... (4 entities in total)
• Functional Keywords: mcba, amide, atp, ligase, anl enzyme
• Biological source: Marinactinospora thermotolerans
• Total number of polymer chains: 5
• Total formula weight: 268748.64

Authors

Rowlinson, B.,Petchey, M.,Grogan, G. (deposition date: 2019-09-03, release date: 2020-04-22, Last modification date: 2024-01-24)

Primary citation

Petchey, M.R.,Rowlinson, B.,Lloyd, R.C.,Fairlamb, I.J.S.,Grogan, G.
Biocatalytic Synthesis of Moclobemide Using the Amide Bond Synthetase McbA Coupled with an ATP Recycling System.
Acs Catalysis, 10:4659-4663, 2020

PubMed Abstract: The biocatalytic synthesis of amides from carboxylic acids and primary amines in aqueous media can be achieved using the ATP-dependent amide bond synthetase McbA, via an adenylate intermediate, using only 1.5 equiv of the amine nucleophile. Following earlier studies that characterized the broad carboxylic acid specificity of McbA, we now show that, in addition to the natural amine substrate 2-phenylethylamine, a range of simple aliphatic amines, including methylamine, butylamine, and hexylamine, and propargylamine are coupled efficiently to the native carboxylic acid substrate 1-acetyl-9-β-carboline-3-carboxylic acid by the enzyme, to give amide products with up to >99% conversion. The structure of wild-type McbA in its amidation conformation, coupled with modeling and mutational studies, reveal an amine access tunnel and a possible role for residue D201 in amine activation. Amide couplings were slower with anilines and alicyclic secondary amines such as pyrrolidine and piperidine. The broader substrate specificity of McbA was exploited in the synthesis of the monoamine oxidase A inhibitor moclobemide, through the reaction of 4-chlorobenzoic acid with 1.5 equiv of 4-(2-aminoethyl)morpholine, and utilizing polyphosphate kinases PPK and PPK in the presence of polyphosphoric acid and 0.1 equiv of ATP, required for recycling of the cofactor.

PubMed: 32337091
DOI: 10.1021/acscatal.0c00929

Experimental method

X-RAY DIFFRACTION (2.59 Å)