The L-alanosine gene cluster encodes a pathway for diazeniumdiolate biosynthesis

Abstract

N-nitroso-containing natural products are bioactive metabolites with antibacterial and anticancer properties. In particular, compounds containing the diazeniumdiolate (Nnitrosohydroxylamine) group display a wide range of bioactivities ranging from cytotoxicity to metal chelation. Despite the importance of this structural motif, knowledge of its biosynthesis is limited. Herein, we describe the discovery of a biosynthetic gene cluster in Streptomyces alanosinicus ATCC 15710 responsible for producing the diazeniumdiolate natural product L-alanosine. Gene disruption and stable isotope feeding experiments identified essential biosynthetic genes and revealed the nitrogen source of the N-nitroso group. Additional biochemical characterization of the biosynthetic enzymes revealed that the non-proteinogenic amino acid L-2,3diaminopropionic acid (L-Dap) is synthesized and loaded onto a peptidyl carrier protein (PCP) domain in L-alanosine biosynthesis, which we propose may be a mechanism of handling unstable intermediates generated en route to the diazeniumdiolate. This research framework will facilitate efforts to determine the biochemistry of diazeniumdiolate formation.[a]T.

Synthetic and biosynthetic routes to nitrogen–nitrogen bonds

“…Alanosine, fragin, gramibactin. Recently, Balskus and coworkers and our group also independently reported the biosynthetic gene cluster of L-alanosine 175 from the original producer Streptomyces alanosinicus 157,158 (Fig. 32A).…”

Mitigation of Pseudomonas syringae virulence by signal inactivation

“…While valdiazen (1) controls the production of an antifungal agent in the opportunistic human pathogen H111 (18), we show that leudiazen (2) controls mangotoxin production in the plant pathogen Pss. The biosynthesis and chemical properties of diazeniumdiolate natural products have been recently investigated in several studies (18)(19)(20)(23)(24)(25)(26). A remarkable aspect of leudiazen in contrast with other diazeniumdiolates is its volatility and the ability to be transmitted through the air (Fig.…”

Biosynthesis of the unusual carbon skeleton of nocuolin A

“…For instance, it is unclear whether the central carbon scaffold of 1 derives from a single fatty acid (FA) precursor or if it is the product of carbon-carbon (C-C) bond formation between two shorter-chain substrates. The biosynthetic origin of the 3-hydroxypropanoyl moiety and the oxadiazine ring are also intriguing, and so it the basis for N-N bond formation, as there are few examples of characterized N-N bond-forming enzymes 10,11 and no homologs of such enzymes are present in the noc BGC.…”