Fig. 4. Characterisation of the amino acid selection and activation characteristics of the final NRPS module from teicoplanin biosynthesis (Tcp12). (A) Alternate constructs of Tcp12, the final module from the teicoplanin NRPS, were designed in order to remove the C-terminal TE-domain in order to prevent unwanted peptide hydrolysis during subsequent C-domain assays (Tcp12_ΔTE1, Tcp12_ΔTE2, Tcp12_ΔTE3). NRPS domain descriptions: C, condensation; A, adenylation; PCP, peptidyl carrier protein; X, P450 (Oxy) recruitment; TE, thioesterase. (B) Amino acid selectivity of the A-domain of the apo-Tcp12 protein for the natural substrate Dpg (l-3,5-dihydroxyphenylglycine) as well as related Phg substrates (4-Hpg: l-4-hydroxylphenylglycine; 3-Hpg: l-3-hydroxylphenylglycine; 4-Hpg: l-phenylglycine).
