Dataset Information

Evolution-guided adaptation of an adenylation domain substrate specificity to an unusual amino acid.

ABSTRACT: Adenylation domains CcbC and LmbC control the specific incorporation of amino acid precursors in the biosynthesis of lincosamide antibiotics celesticetin and lincomycin. Both proteins originate from a common L-proline-specific ancestor, but LmbC was evolutionary adapted to use an unusual substrate, (2S,4R)-4-propyl-proline (PPL). Using site-directed mutagenesis of the LmbC substrate binding pocket and an ATP-[32P]PPi exchange assay, three residues, G308, A207 and L246, were identified as crucial for the PPL activation, presumably forming together a channel of a proper size, shape and hydrophobicity to accommodate the propyl side chain of PPL. Subsequently, we experimentally simulated the molecular evolution leading from L-proline-specific substrate binding pocket to the PPL-specific LmbC. The mere change of three amino acid residues in originally strictly L-proline-specific CcbC switched its substrate specificity to prefer PPL and even synthetic alkyl-L-proline derivatives with prolonged side chain. This is the first time that such a comparative study provided an evidence of the evolutionary relevant adaptation of the adenylation domain substrate binding pocket to a new sterically different substrate by a few point mutations. The herein experimentally simulated rearrangement of the substrate binding pocket seems to be the general principle of the de novo genesis of adenylation domains' unusual substrate specificities. However, to keep the overall natural catalytic efficiency of the enzyme, a more comprehensive rearrangement of the whole protein would probably be employed within natural evolution process.

SUBMITTER: Vobruba S

PROVIDER: S-EPMC5730197 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Evolution-guided adaptation of an adenylation domain substrate specificity to an unusual amino acid.

Vobruba Simon S Kadlcik Stanislav S Gazak Radek R Janata Jiri J

PloS one 20171214 12

Adenylation domains CcbC and LmbC control the specific incorporation of amino acid precursors in the biosynthesis of lincosamide antibiotics celesticetin and lincomycin. Both proteins originate from a common L-proline-specific ancestor, but LmbC was evolutionary adapted to use an unusual substrate, (2S,4R)-4-propyl-proline (PPL). Using site-directed mutagenesis of the LmbC substrate binding pocket and an ATP-[32P]PPi exchange assay, three residues, G308, A207 and L246, were identified as crucial ...[more]

PMID: 29240815

Similar Datasets

Project description:BackgroundCreating designer molecules using a combination of select domains from polyketide synthases and/or nonribosomal peptide synthetases (NRPS) continues to be a synthetic goal. However, an incomplete understanding of how protein-protein interactions and dynamics affect each of the domain functions stands as a major obstacle in the field. Of particular interest is understanding the basis for a class of methyltransferase domains (MT) that are found embedded within the adenylation domain (A) of fungal NRPS systems instead of in an end-to-end architecture.ResultsThe MT domain from bassianolide synthetase (BSLS) was removed and the truncated enzyme BSLS-ΔMT was recombinantly expressed. The biosynthesis of bassianolide was abolished and N-desmethylbassianolide was produced in low yields. Co-expression of BSLS-ΔMT with standalone MT did not recover bassianolide biosynthesis. In order to address the functional implications of the protein insertion, we characterized the N-methyltransferase activity of the MT domain as both the isolated domain (MTBSLS) and as part of the full NRPS megaenzyme. Surprisingly, the MTBSLS construct demonstrated a relaxed substrate specificity and preferentially methylated an amino acid (L-Phe-SNAC) that is rarely incorporated into the final product. By testing the preference of a series of MT constructs (BSLS, MTBSLS, cMT, XLcMT, and aMT) to L-Phe-SNAC and L-Leu-SNAC, we further showed that restricting and/or fixing the termini of the MTBSLS by crosslinking or embedding the MT within an A domain narrowed the substrate specificity of the methyltransferase toward L-Leu-SNAC, the preferred substrate for the BSLS megaenzyme.ConclusionsThe embedding of MT into the A2 domain of BSLS is not required for the product assembly, but is critical for the overall yields of the final products. The substrate specificity of MT is significantly affected by the protein context within which it is present. While A domains are known to be responsible for selecting and activating the biosynthetic precursors for NRPS systems, our results suggest that embedding the MT acts as a secondary gatekeeper for the assembly line. This work thus provides new insights into the embedded MT domain in NRPSs, which will facilitate further engineering of this type of biosynthetic machinery to create structural diversity in natural products.

Dataset Information

Evolution-guided adaptation of an adenylation domain substrate specificity to an unusual amino acid.

Publications

Evolution-guided adaptation of an adenylation domain substrate specificity to an unusual amino acid.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets