5EXK

Crystal structure of M. tuberculosis lipoyl synthase with 6-thiooctanoyl peptide intermediate

5EXK の概要

• エントリーDOI: 10.2210/pdb5exk/pdb
• 関連するPDBエントリー: 5EXI 5EXJ
• 分子名称: Lipoyl synthase, Octanoylated peptide from M. tuberculosis H protein, FE3-S4 CLUSTER, ... (10 entities in total)
• 機能のキーワード: auxiliary iron-sulfur cluster, adomet radical, radical sam, sulfur insertion, transferase
• 由来する生物種: Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv); 詳細
• タンパク質・核酸の鎖数: 12
• 化学式量合計: 234256.65

構造登録者

McLaughlin, M.I.,Lanz, N.D.,Goldman, P.J.,Lee, K.-H.,Booker, S.J.,Drennan, C.L. (登録日: 2015-11-23, 公開日: 2016-08-10, 最終更新日: 2025-04-02)

主引用文献

McLaughlin, M.I.,Lanz, N.D.,Goldman, P.J.,Lee, K.H.,Booker, S.J.,Drennan, C.L.
Crystallographic snapshots of sulfur insertion by lipoyl synthase.
Proc.Natl.Acad.Sci.USA, 113:9446-9450, 2016

PubMed Abstract: Lipoyl synthase (LipA) catalyzes the insertion of two sulfur atoms at the unactivated C6 and C8 positions of a protein-bound octanoyl chain to produce the lipoyl cofactor. To activate its substrate for sulfur insertion, LipA uses a [4Fe-4S] cluster and S-adenosylmethionine (AdoMet) radical chemistry; the remainder of the reaction mechanism, especially the source of the sulfur, has been less clear. One controversial proposal involves the removal of sulfur from a second (auxiliary) [4Fe-4S] cluster on the enzyme, resulting in destruction of the cluster during each round of catalysis. Here, we present two high-resolution crystal structures of LipA from Mycobacterium tuberculosis: one in its resting state and one at an intermediate state during turnover. In the resting state, an auxiliary [4Fe-4S] cluster has an unusual serine ligation to one of the irons. After reaction with an octanoyllysine-containing 8-mer peptide substrate and 1 eq AdoMet, conditions that allow for the first sulfur insertion but not the second insertion, the serine ligand dissociates from the cluster, the iron ion is lost, and a sulfur atom that is still part of the cluster becomes covalently attached to C6 of the octanoyl substrate. This intermediate structure provides a clear picture of iron-sulfur cluster destruction in action, supporting the role of the auxiliary cluster as the sulfur source in the LipA reaction and describing a radical strategy for sulfur incorporation into completely unactivated substrates.

PubMed: 27506792
DOI: 10.1073/pnas.1602486113

実験手法

X-RAY DIFFRACTION (1.86 Å)