Abstract

The soil bacterial genus Variovorax produce distinct photoreactive siderophores that may play a crucial role in the iron cycle within the rhizosphere. This study focused on exploring the natural products of the soil-isolated Variovorax sp. H002, leading to the isolation of variochelins A–E (1–5), a series of lipohexapeptide siderophores. NMR and MS/MS analyses revealed that these siderophores share a common core structure – a linear hexapeptide with β-hydroxyaspartate and hydroxamate functional groups, serving in iron-binding coordination. Three new variochelins C–E (3–5) were characterized by varied fatty acyl groups at their N-termini; notably, 4 and 5 represent the first variochelins with N-terminal unsaturated fatty acyl groups. Furthermore, the variochelin biosynthetic gene cluster was identified through draft genome sequencing and gene knockout experiments. Compounds 1–5 exhibited antimicrobial activities against Gram-negative bacteria, including several soil-isolated plant pathogens.

Beilstein J. Org. Chem. 2024, 20, 692–700. doi:10.3762/bjoc.20.63

摘要

土壤细菌属Variovorax产生独特的光反应性铁载体，可能在根际铁循环中发挥至关重要的作用。本研究的重点是探索土壤分离的Variovorax sp. 的天然产物。 H002，导致分离出一系列脂六肽铁载体variochelins A–E ( 1 – 5 )。 NMR 和 MS/MS 分析表明，这些铁载体具有共同的核心结构——具有 β-羟基天冬氨酸和异羟肟酸官能团的线性六肽，在铁结合协调中发挥作用。三种新的 variochelins C–E ( 3 – 5 ) 的特点是其N末端有不同的脂肪酰基；值得注意的是，4和5代表第一个具有N端不饱和脂肪酰基的variochelins。此外，通过基因组草图测序和基因敲除实验鉴定了variochelin生物合成基因簇。化合物1 – 5对革兰氏阴性细菌（包括几种从土壤中分离的植物病原体）表现出抗菌活性。

贝尔斯坦 J. 组织。化学。 2024, 20, 692–700。 doi:10.3762/bjoc.20.63