engleski

ATPase activity of non-ribosomal peptide synthetases (NRPS)

Adenylation domains of non-ribosomal peptide synthetases (NRPS) catalyze the formation of aminoacyl adenylates, and in addition synthesize mono and dinucleoside polyphosphates. Here, we show that NRPS systems furthermore contain an ATPase activity in the range of up to 2 Pi/min. The hydrolysis rate by apo-tyrocidine synthetase 1 (apo-TY1) is enhanced in the presence of non-cognate amino acid substrates, correlating well with their structural features and the diminishing adenylation efficiency. A comparative analysis of the functional relevance of an analogous sequence motif in P-type ATPases and adenylate kinases allowed a putative assignment of the invariant aspartate residue from the TGDLA(V)R(K) core sequence in NRPS as the Mg2+ binding site. Less pronounced variations in ATPase activity are observed in domains with relaxed amino acid specificity of gramicidin S synthetase 2 (GS2) and δ -(L-aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS), known to produce a set of substitutional variants of the respective peptide product. These results disclose new perspectives about the mode of substrate selection by NRPS.

adenylation domain; amino acid specificity; ATP binding; Pi release

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