Biosynthesis of the N–N‐Bond‐Containing Compound l‐Alanosine

Abstract

The formation of a N−N bond is a unique biochemical transformation, and nature employs diverse biosynthetic strategies to activate nitrogen for bond formation. Among molecules that contain a N−N bond, biosynthetic routes to diazeniumdiolates remain enigmatic. We here report the biosynthetic pathway for the diazeniumdiolate‐containing amino acid l‐alanosine. Our work reveals that the two nitrogen atoms in the diazeniumdiolate of l‐alanosine arise from glutamic acid and aspartic acid, and we clarify the early steps of the biosynthetic pathway by using both in vitro and in vivo approaches. Our work demonstrates a peptidyl‐carrier‐protein‐based mechanism for activation of the precursor l‐diaminopropionate, and we also show that nitric oxide can participate in non‐enzymatic diazeniumdiolate formation. Furthermore, we demonstrate that the gene alnA, which encodes a fusion protein with an N‐terminal cupin domain and a C‐terminal AraC‐like DNA‐binding domain, is required for alanosine biosynthesis.

Biosynthesis and Structure–Activity Relationship Investigations of the Diazeniumdiolate Antifungal Agent Fragin

“…We proposed that 3 would be the initial substrate of the NRPS complex HamD and that the enzymes of unknown functions, HamA and HamE, and the N ‐oxygenase analogue HamC would transform the amine into the diazeniumdiolate. This hypothesis is supported by the previous identification of several modifications occurring during chain elongation and by recent investigations of alanosine biosynthesis . The compound would be released as an aldehyde from the reductase domain of HamD and further reduced through the action of the same enzyme to afford 2 .…”

Nitric oxide as a source for bacterial triazole biosynthesis

“…The most frequently used precursors for N-N bond formation are hydroxylamines (such as L-N 5 -OH-Ornthine in piperazate pathway 9 , N-isobutylhydrdoxylamine in valanimycin pathway 37 , and L-N 6 -OH-lysine in the pathways of s56-p1 14 , pyrazomycin 16 and formycin 17,38 ) and nitric acid, which derives from the α-amine of L-aspartic acid by the enzyme pair CreE and CreD 10 . The flavin monooxygenase CreE and nitrosuccinate lyase CreD were first characterized in the cremeomycin pathway, and their homologs were subsequently identified in the pathways of fosfazinomycin, and kinamycin, triacsins and alanosine 15,[21][22][23] .…”

“…While the biosynthetic routes to natural products containing a N-N bond have received great interest and are starting to be revealed, how a triazole ring is assembled in nature remains unknown [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] . Elucidation of its biosynthetic mechanism could likely be helpful to the design of synthetic biology approaches for producing triazoles.…”

A Volatile Signal Controls Virulence in the Plant PathogenPseudomonas syringaepv.syringaeand a Strategy for Infection Control in Organic Farming

“…27 During the last two years, this functional group has been also associated with the discovery of a new class of siderophore [29][30][31] and the identification of alanosine gene cluster. 32,33 In Burkholderia cenocepacia H111, hamA, C, D, and E genes, which are homologs of the mgo genes, were shown to be involved in the biosynthesis of valdiazen (1) 27,34 The proposed biosynthesis of valdiazen (1) starts with L-valine as the initial NRPS substrate and the diazeniumdiolate functional group is hypothesized to be formed by tailoring enzymes.…”