The cyanobactin heterocyclase enzyme: a processive adenylase that operates with a defined order of reaction.
The cyanobactin heterocyclase enzyme: a processive adenylase that operates with a defined order of reaction.
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DOI：
10.1002/anie.201306302
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发表时间：
2013-12-23
影响因子：
16.6
通讯作者：
Naismith, James H.
中科院分区：
文献类型：
--
作者：
Koehnke, Jesko;Bent, Andrew F.;Zollman, David;Smith, Kieran;Houssen, Wael E.;Zhu, Xiaofeng;Mann, Greg;Lebl, Tomas;Scharff, Richard;Shirran, Sally;Botting, Catherine H.;Jaspars, Marcel;Schwarz-Linek, Ulrich;Naismith, James H.
杂环是有机化学中反复出现的标志性结构。将五元环引入蛋白质骨架中是合成上具有挑战性的，但是许多基于肽的生物活性天然产物含有此类Ser-、Thr-和Cys-衍生的杂环[1]，因此非常需要将其引入的简便途径。更一般地，噻唑啉和恶唑啉以及它们的氧化形式（噻唑和恶唑）存在于各种批准的药物、药物先导物和毒素中。[2]蓝藻Prochloron spp.产生多个大环蓝藻，这是已知的trunkamides（七个或八个残基）和patellamides（八个残基）。这些天然产物来源于两种不同的核糖体前体肽（表示为TruE和PatE），并且每种核糖体肽含有多个不同的核心肽。在TrueE（和PatE）中，每个核心肽在N末端侧接保守的五残基蛋白酶特征[3]，在C末端侧接保守的大环化特征（A/SYDG;方案1）。正是核心肽继续成为不同的天然产物。在trunkamides和patellamides（以及其他蓝藻）中，这些产物具有多个杂环半胱氨酸和/或丝氨酸和苏氨酸氨基酸。所有氰基菌素核糖体前体肽（沿着核心肽及其侧翼区）都具有保守的30至40个残基的N-末端（示意图1）。这种在加工过程中被丢弃的N-末端前导序列被认为是杂环化所必需的。[4]TruE中多个半胱氨酸残基的杂环化由单一酶TruD进行，根据定义，TruD是进行性的。核心肽的氨基酸序列是可变的（支持信息，图S1），因此TruD必须对靶半胱氨酸的直接序列背景部分不敏感（方案1）。此外，TrueE中靶半胱氨酸相对于前导序列的位置在核心肽内和核心肽之间变化。这种灵活性表明，TruD可能对合成化学家有价值。Patellamide途径中的相应酶表示为PatD。TruD和PatD同样很好地加工其他酶前体肽底物中的半胱氨酸残基[4，5]; TruD加工丝氨酸和苏氨酸残基的效果不如PatD。[4，5]酶的可重复性反映了酶（图S2）和底物N-末端前导序列（图S1）中的高度序列同一性。最近研究了半胱氨酸的杂环化以形成作为微菌素（噻唑/恶唑修饰的微菌素，或TOP3）的一部分的噻唑啉，并鉴定了负责的ATP Mg 2+依赖性杂环酶BalhD。[6]BalhD与TruD的C端400个残基同源，而第二种蛋白BalhC与N端300个残基匹配（图2）。当BalhD和BalhC都存在时，微球蛋白底物的杂环化被加速，并且只有当两种蛋白质都存在时，才能稳健地测量磷酸盐释放。排除了BalhD生产焦磷酸盐的可能性，建议BalhD通过
Heterocyclic rings are a recurring and iconic motif in organic chemistry. The introduction of five-membered rings into protein backbones is synthetically challenging, but many peptide-based biologically active natural products contain such Ser-, Thr-, and Cys-derived heterocycles [1] and therefore a facile route to their introduction is highly desirable. More generally thiazolines and oxazolines, as well as their oxidized forms (thiazoles and oxazoles), are found in a variety of approved drugs, drug leads, and toxins.[2] The cyanobacterium Prochloron spp. produces multiple macrocyclic cyanobactins, which are known as the trunkamides (seven or eight residues) and the patellamides (eight residues). These natural products originate from two different ribosomal precursor peptides (denoted TruE and PatE), and each ribosomal peptide contains multiple distinct core peptides. In TruE (and PatE), each of the core peptides is flanked at the N-terminus by a conserved five-residue protease signature [3] and at the C-terminus by a conserved macrocyclization signature (A/SYDG; Scheme 1). It is the core peptides that go on to become the different natural products. In trunkamides and patellamides (as well as other cyanobactins) these products possess multiple heterocyclic cysteine, and/or serine and threonine amino acids. All cyanobactin ribosomal precursor peptides possess (along with the core peptides and their flanking regions) a conserved thirty-to forty-residue N-terminus (Scheme1). This N-terminal leader, which is discarded during processing is thought to be essential for heterocyclization.[4] Heterocyclization of the multiple cysteine residues in TruE is carried out by the single enzyme, TruD, which by definition is processive. The amino acid sequence of the core peptide is variable (Supporting Information, Figure S1) and thus TruD must be in part insensitive to the immediate sequence context of the target cysteine (Scheme 1). Further, the positions of the target cysteines in TruE relative to the leader vary, both within and between core peptides. This flexibility suggests that TruD could be valuable for synthetic chemists. The corresponding enzyme in the patellamide pathway is denoted PatD. TruD and PatD process cysteine residues [4, 5] in the other enzymes precursor peptide substrate equally well; TruD processes serine and threonine residues less well than PatD.[4, 5] The interchangeability of enzymes mirrors the high degree of sequence identity in the enzymes (Figure S2) and substrate N-terminal leader (Figure S1).The heterocyclization of cysteine to form thiazoline as part of the microcins (thiazole/oxazole-modified microcins, or TOMMs) has recently been studied and the responsible ATP Mg2+ dependent heterocyclase BalhD identified.[6] BalhD is homologous to the C-terminal 400 residues of TruD, whilst a second protein BalhC matches the N-terminal 300 residues (FigureS2). When both BalhD and BalhC are present heterocyclization of the microcin substrate is accelerated and only when both proteins are present can phosphate release be robustly measured. Pyrophosphate production by BalhD was ruled out and BalhD was proposed to operate by
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影响因子：
16.8
作者：
Koehnke, Jesko;Bent, Andrew;Houssen, Wael E.;Zollman, David;Morawitz, Falk;Shirran, Sally;Vendome, Jeremie;Nneoyiegbe, Ada F.;Trembleau, Laurent;Botting, Catherine H.;Smith, Margaret C. M.;Jaspars, Marcel;Naismith, James H.
通讯作者：
Naismith, James H.
影响因子：
15
作者：
Dunbar, Kyle L.;Mitchell, Douglas A.
通讯作者：
Mitchell, Douglas A.
影响因子：
3.2
作者：
McIntosh, John A.;Schmidt, Eric W.
通讯作者：
Schmidt, Eric W.
影响因子：
14.8
作者：
Dunbar, Kyle L.;Melby, Joel O.;Mitchell, Douglas A.
通讯作者：
Mitchell, Douglas A.
影响因子：
14.8
作者：
Schmelz, Stefan;Kadi, Nadia;McMahon, Stephen A.;Song, Lijiang;Oves-Costales, Daniel;Oke, Muse;Liu, Huanting;Johnson, Kenneth A.;Carter, Lester G.;Botting, Catherine H.;White, Malcolm F.;Challis, Gregory L.;Naismith, James H.
通讯作者：
Naismith, James H.