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首页> 外文期刊>Biochemistry >A Comparison of Methanobactins from Methylosinus trichosporium OB3b and Methylocystis Strain SB2 Predicts Methanobactins Are Synthesized from Diverse Peptide Precursors Modified To Create a Common Core for Binding and Reducing Copper Ions
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A Comparison of Methanobactins from Methylosinus trichosporium OB3b and Methylocystis Strain SB2 Predicts Methanobactins Are Synthesized from Diverse Peptide Precursors Modified To Create a Common Core for Binding and Reducing Copper Ions

机译：来自甲基毛孢菌OB3b和甲基囊藻菌株SB2的甲烷菌素的比较预测，甲烷菌素是由多种肽前体合成的，这些肽前体经过修饰以形成用于结合和还原铜离子的共同核心。

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Methanobactins (mb) are low-molecular mass, copper-binding molecules secreted by mostnmethanotrophic bacteria. These molecules have been identified for a number of methanotrophs, but onlynthe one produced byMethylosinus trichosporium OB3b (mb-OB3b) has to date been chemically characterized.nHere we report the chemical characterization and copper binding properties of a second methanobactin,nwhich is produced by Methylocystis strain SB2 (mb-SB2). mb-SB2 shows some significant similarities tonmb-OB3b, including its spectral and metal binding properties, and its ability to bind and reduce Cu(II) tonCu(I). Like mb-OB3b, mb-SB2 contains two five-member heterocyclic rings with associated enethiol groups,nwhich together form the copper ion binding site. mb-SB2 also displays some significant differences comparednto mb-OB3b, including the number and types of amino acids used to complete the structure of the molecule,nthe presence of an imidazolone ring in place of one of the oxazolone rings found inmb-OB3b, and the presencenof a sulfate group not found inmb-OB3b. The sulfate is bonded to a threonine-like side chain that is associatednwith one of the heterocyclic rings and may represent the first example of this type of sulfate group found in anbacterially derived peptide. Acid-catalyzed hydrolysis and decarboxylation of the oxazolone rings found innmb-OB3b andmb-SB2 produce pairs of amino acid residues and suggest that both mb-OB3b andmb-SB2 arenderived frompeptides. In support of this, the gene for a ribosomally produced peptide precursor formb-OB3bnhas been identified in the genome ofM. trichosporium OB3b. The gene sequence indicates that the oxazolonenrings inmb-OB3b are derived fromthe combination of a cysteine residue and the carbonyl fromthe precedingnresidue in the peptide sequence. Taken together, the results suggest methanobactins make up a structurallyndiverse group of ribosomally produced, peptide-derived molecules, which share a common pair of five-nmember rings with associated enethiol groups that are able to bind, reduce, and stabilize copper ions in annaqueous environment.
机译：甲烷菌素（mb）是大多数甲基营养型细菌分泌的低分子量铜结合分子。这些分子已被鉴定为多种甲烷氧化菌，但迄今为止，只有三甲基甲基孢子虫OB3b（mb-OB3b）产生的一种分子已经过化学表征。菌株SB2（mb-SB2）。 mb-SB2显示出tonmb-OB3b的一些显着相似之处，包括其光谱和金属结合特性，以及其结合和还原Cu（II）tonCu（I）的能力。像mb-OB3b一样，mb-SB2包含两个带有相关联的烯硫醇基的五元杂环，它们一起形成铜离子结合位点。 mb-SB2与mb-OB3b相比也显示出一些显着差异，包括用于完成分子结构的氨基酸的数量和类型，存在咪唑啉酮环代替在inmb-OB3b中发现的恶唑酮环之一和在mbmb-OB3b中未发现硫酸根。硫酸盐结合到与一个杂环相连的苏氨酸样侧链，并且可以代表在细菌衍生肽中发现的这种硫酸盐基团的第一个例子。在nmbb-OB3b和mb-SB2中发现的恶唑酮环的酸催化水解和脱羧反应会产生成对的氨基酸残基，这表明mb-OB3b和mb-SB2均来自肽。为此，已经在M的基因组中鉴定了核糖体产生的肽前体formb-OB3bn的基因。毛孢霉OB3b。基因序列表明恶唑酮环inmb-OB3b来源于半胱氨酸残基和肽序列中先前残基的羰基的组合。两者合计，结果表明，甲烷菌素构成核糖体生产的，肽衍生的分子的结构上多样化的组，它们与具有相关联的烯硫醇基团的一对五元环具有共同的对，所述烯属硫醇基团能够在酸性环境中结合，还原和稳定铜离子。

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