Jun Yoshitake, Takahiro Shibata, Miho Chikazawa, Koji Uchida
{"title":"Autoxidation of ascorbate mediates lysine <i>N</i>-pyrrolation.","authors":"Jun Yoshitake, Takahiro Shibata, Miho Chikazawa, Koji Uchida","doi":"10.1080/10715762.2023.2174865","DOIUrl":null,"url":null,"abstract":"<p><p>Protein <i>N</i>-pyrrolation, which converts lysine residues to <i>N</i><sup>ε</sup>-pyrrole-l-lysine (pyrK), is a naturally occurring covalent modification. The pyrrolated proteins have a unique property of binding to DNA-staining agents, such as SYBR Green I (SG), and anti-DNA antibodies, suggesting a physiologically relevant modification that gives rise to DNA mimic protein. These properties of pyrrolated protein are suggested to be associated with innate and autoimmune responses. Short-chain aldehydes derived from lipid peroxidation are thought to be involved in the formation of pyrK. We now report that similar lysine <i>N</i>-pyrrolation also occurs during the metal-catalyzed oxidation of proteins with ascorbate. When human serum albumin (HSA) was incubated with Fe<sup>2+</sup>/ascorbate in the presence and absence of docosahexaenoic acid, the protein was converted to SG-binding proteins even without the polyunsaturated fatty acid. The formation of SG-binding proteins by Fe<sup>2+</sup>/ascorbate was accompanied by the formation of pyrK, which was also detected in ascorbate-treated hemoglobin. Moreover, the metal-catalyzed oxidation of ascorbate produced the pyrrolation factors, glycolaldehyde and glyoxal. These results and the observations that sera from autoimmune-prone MRL-<i>lpr</i> mice recognized modified proteins with Fe<sup>2+</sup>/ascorbate and with glycolaldehyde/glyoxal suggest that the autoxidation of ascorbate, as well as lipid peroxidation, can be a source of autoantigenic <i>N</i>-pyrrolated proteins. Our findings revealed a possible function of ascorbate as an endogenous source of pyrrolated proteins and suggested that the pyrK residues generated in proteins may play a role in the innate and autoimmune responses associated with the oxidative metabolism of ascorbate.</p>","PeriodicalId":12411,"journal":{"name":"Free Radical Research","volume":null,"pages":null},"PeriodicalIF":3.6000,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Free Radical Research","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1080/10715762.2023.2174865","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 1
Abstract
Protein N-pyrrolation, which converts lysine residues to Nε-pyrrole-l-lysine (pyrK), is a naturally occurring covalent modification. The pyrrolated proteins have a unique property of binding to DNA-staining agents, such as SYBR Green I (SG), and anti-DNA antibodies, suggesting a physiologically relevant modification that gives rise to DNA mimic protein. These properties of pyrrolated protein are suggested to be associated with innate and autoimmune responses. Short-chain aldehydes derived from lipid peroxidation are thought to be involved in the formation of pyrK. We now report that similar lysine N-pyrrolation also occurs during the metal-catalyzed oxidation of proteins with ascorbate. When human serum albumin (HSA) was incubated with Fe2+/ascorbate in the presence and absence of docosahexaenoic acid, the protein was converted to SG-binding proteins even without the polyunsaturated fatty acid. The formation of SG-binding proteins by Fe2+/ascorbate was accompanied by the formation of pyrK, which was also detected in ascorbate-treated hemoglobin. Moreover, the metal-catalyzed oxidation of ascorbate produced the pyrrolation factors, glycolaldehyde and glyoxal. These results and the observations that sera from autoimmune-prone MRL-lpr mice recognized modified proteins with Fe2+/ascorbate and with glycolaldehyde/glyoxal suggest that the autoxidation of ascorbate, as well as lipid peroxidation, can be a source of autoantigenic N-pyrrolated proteins. Our findings revealed a possible function of ascorbate as an endogenous source of pyrrolated proteins and suggested that the pyrK residues generated in proteins may play a role in the innate and autoimmune responses associated with the oxidative metabolism of ascorbate.
蛋白质N-pyrrolation将赖氨酸残基转化为nε -pyrrole-l-赖氨酸(pyrK),是一种自然发生的共价修饰。热解蛋白具有与DNA染色剂(如SYBR Green I (SG))和抗DNA抗体结合的独特特性,表明与生理相关的修饰产生了DNA模拟蛋白。这些特性被认为与先天和自身免疫反应有关。脂质过氧化产生的短链醛被认为参与了pyrK的形成。我们现在报道,类似的赖氨酸n -吡啶化也发生在金属催化蛋白质与抗坏血酸的氧化过程中。当人血清白蛋白(HSA)与铁(Fe2+) /抗坏血酸(asc)在存在和不存在二十二碳六烯酸的情况下孵育时,即使没有多不饱和脂肪酸,蛋白质也能转化为sg结合蛋白。Fe2+/抗坏血酸形成sg结合蛋白的同时,也会形成pyrK,这在抗坏血酸处理的血红蛋白中也能检测到。此外,金属催化的抗坏血酸氧化产生了热解因子,乙醇醛和乙二醛。这些结果以及对自身免疫易感的MRL-lpr小鼠血清识别Fe2+/抗坏血酸和乙醇醛/乙二醛修饰蛋白的观察表明,抗坏血酸的自氧化以及脂质过氧化可能是自身抗原n -吡咯蛋白的来源。我们的研究结果揭示了抗坏血酸作为一种内源性热相关蛋白的可能功能,并提示蛋白质中产生的pyrK残基可能在与抗坏血酸氧化代谢相关的先天和自身免疫反应中发挥作用。
期刊介绍:
Free Radical Research publishes high-quality research papers, hypotheses and reviews in free radicals and other reactive species in biological, clinical, environmental and other systems; redox signalling; antioxidants, including diet-derived antioxidants and other relevant aspects of human nutrition; and oxidative damage, mechanisms and measurement.