Sparsomycin Biosynthesis Highlights Unusual Module Architecture and Processing Mechanism in Non-ribosomal Peptide Synthetase

Abstract

Sparsomycin is a model protein synthesis inhibitor that blocks peptide bond formation by binding to the large ribosome subunit. It is a unique dipeptidyl alcohol, consisting of a uracil acrylic acid moiety and a monooxo-dithioacetal group. To elucidate the biosynthetic logic of sparsomycin, a biosynthetic gene cluster for sparsomycin was identified from the producer Streptomyces sparsogenes by genome mining, targeted gene mutations, and heterologous expression. Both the genetic and enzymatic studies revealed a minimum set of non-ribosomal peptide synthetases needed for generating the dipeptidyl alcohol scaffold of sparsomycin, featuring unusual mechanisms in dipeptidyl assembly and off-loading.

Sparsomycin – a Review and Re-assessment

“…83 It was recognized that timing of the loss of the side chain of 75 could possibly occur earlier in the biogenetic scheme. In this regard, [6-13 C]-6-hydroxyindole (85) was not incorporated into 1, and neither were [2-13 C]-7-hydroxytryptophan (86) or [2-13 C]-7-hydroxyindole (87). The last steps in the formation of 13 were investigated with the pyrimidine derivative 88 (hypothetically derived through amination and cyclization of 84) which was labeled at the C-2 position and was well incorporated into 1.…”

“…Alternative biogenesis of the uracil acrylic acid moiety 13 of sparsomycin (1) 83 It was 18 years before further investigations on the biosynthesis of sparsomycin (1) were reported, this time at the gene level. 86,87 The genome of S. sparsogenes ATCC 25498 was probed through bioinformatics for homologs of xanthine dehydrogenase (XDH) and an NRPS. This search yielded a single gene cluster of ~30 kb and 24 orfs (spaA-spaX).…”

“…Mutation of spsQ and spsR abrogated the formation of 1. 86 One question was evident immediately from the operon. With only two substrates, why were there three A domains for precursor activation?…”

Nicht‐ribosomale Peptidsynthese – Prinzipien und Perspektiven

“…Die Welt der NRPSs bietet vielerlei alternative Mechanismen, so auch für die Te‐unabhängige Freisetzung (Abbildung ). Wie in Abschnitt 3.6.3 beschrieben, können NAD(P)H‐abhängige Reduktionsdomänen (R) durch die Reduktion des Peptidyl‐ S ‐Ppant‐Thioesters eine Peptidfreisetzung erzielen (Abbildung c) . Fungale NRPSs, z.…”

“…In der Kristallstruktur der Apo‐T‐R AusA ‐Didomäne fehlte jegliche Elektronendichte für die T‐Domäne, was deren multiple Orientierungen bezüglich der R‐Domäne unterstreicht . Im Biosynthesegencluster für den Ribosomeninhibitor Sparsomycin aus Streptomyces sparsogenes entdeckte man erst kürzlich eine einzelständige R‐Domäne (SpsM) . Diese Entdeckung verdeutlicht, dass die Peptidyl‐Ppant‐T‐Domäne befähigt ist, spezifisch die in trans agierende R‐Domäne für die reduktive Spaltung zu rekrutieren.…”