Mixing Up the Pieces of the Desferrioxamine B Jigsaw Defines the Biosynthetic Sequence Catalyzed by DesD

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• 作者：Thomas J. Telfer ; Michael P. Gotsbacher ; Cho Zin Soe ; Rachel Codd
• 刊名：ACS Chemical Biology
• 出版年：2016
• 出版时间：May 20, 2016
• 年：2016
• 卷：11
• 期：5
• 页码：1452-1462
• 全文大小：790K
• 年卷期：0
• ISSN：1554-8937

文摘

Late-stage assembly of the trimeric linear siderophore desferrioxamine B (DFOB) native to Streptomyces pilosus involves two DesD-catalyzed condensation reactions between one N-acetyl-N-hydroxy-1,5-diaminopentane (AHDP) unit and two N-succinyl-N-hydroxy-1,5-diaminopentane (SHDP) units. AHDP and SHDP are products of DesBC-catalyzed reactions of the native diamine substrate 1,5-diaminopentane (DP). The sequence of DesD-catalyzed DFOB biosynthesis was delineated by analyzing the distribution of DFOB analogues and dimeric precursors assembled by S. pilosus in medium containing 1,4-diamino-2(E)-butene (E-DBE). Seven unsaturated DFOB analogues were produced that were partially resolved by liquid chromatography (LC). Mass spectrometry (MS) measurements reported on the combination of E-DBE- and DP-derived substrates in each trimer (uDFOA₁ series, 1:2; uDFOA₂ series, 2:1; uDFOA₃, 3:0). MS/MS fragmentation patterns reported on the absolute position of the substrate derivative at the N-acetylated terminus, the internal region, or the amine terminus of the trimer. The uDFOA₁ and uDFOA₂ series each comprised three constitutional isomers (binary notation (DP-derived substrate “0,” E-DBE-derived substrate “1”); direction, N-acetylated-internal-amine): uDFOA₁[001], uDFOA₁[010], uDFOA₁[100]; and uDFOA₂[011], uDFOA₂[110], and uDFOA₂[101]. E-DBE completely replaced DP in uDFOA₃[111]. Relative concentrations of the uDFOA₁ series were uDFOA₁[001] ≫ uDFOA₁[100] > uDFOA₁[010] and of the uDFOA₂ series, uDFOA₂[101] > uDFOA₂[011] ≫ uDFOA₂[110]. Dimeric compounds assembled from one N-acetylated and one N-succinylated substrate derivative were detected as trimer precursors: dDFX[00-] ≫ udDFX[10-] > udDFX[01-] (d = dimer, vacant position “-”). Relative concentrations of all species were consistent with the biosynthetic sequence: (i) SHDP activation, (ii) condensation with AHDP to form AHDP-SHDP, (iii) SHDP activation, and (iv) condensation with AHDP-SHDP to form DFOB.