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2024年2月9日发(作者：运动通讯稿)

生物化学与生物物理进展

Progress in Biochemistry and Biophysics

发布日期：（编辑部填写）

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补充材料二

Supplementary data 2

病理性α-SYN的化学修饰形式的生物信息学数据分析

An Analysis of Bioinformatics Datats Related to Chemical Modification Forms of

Pathological α-SYN

i．在DLB病人LBs内，α-SYN的磷酸化修饰率达90%（而在正常脑内，生理性α-SYN的磷酸化修饰[1]率仅4%）．α-SYN的丝氨酸残基-87（Ser-87）、Ser-125和Ser-129是主要的磷酸化修饰位点，而且Ser-129位点的磷酸化修饰水平最高[2]．蛋白质磷酸化修饰有助于稳定α-SYN的β-片层[3]．蛋白质磷酸化修饰促进α-SYN进行纤维化聚集[3]．

ii．在PD病人LBs内，α-SYN的氧化修饰水平不低于它的磷酸化修饰水平[3]．首先，α-SYN的酪氨酸残基-39（Tyr-39）、Tyr-125、Tyr-133和Tyr-136是一组氧化修饰位点，氧化修饰方式是硝基化和羟基氧化[2]．硝基化将弱极性的Tyr转变为强极性的3-硝基酪氨酸，α-SYN由此不能形成稳定的β-片层；羟基氧化，5]将两个Tyr转变为一个Tyr同二聚体，α-SYN借此形成分子内、间交联物[4Met转变为刚性和极性均较强的亚砜和砜，从而弱化了α-SYN的β-片层[6结合于α-SYN[2，3，8]．其次，α-SYN的蛋氨酸残基-1（Met-1）、Met-5、Met-116和Met-127是另外一组氧化修饰位点，氧化方式是巯基氧化[2]．巯基氧化将，7]．再次，DA及其氧化代谢物（包括超氧阴离子、过氧化氢等过氧化物以及多巴醌、5,6-二羟基吲哚、5,6-吲哚醌等DA衍生物）广泛地共价．这种非特异性氧化修饰方式干扰DA及其氧化代谢物在生理状态下特异地非共价结合于α-SYN，并且进一步干扰α-SYN形成β-片层[9-11]．蛋白质氧化修饰促进α-SYN进行非纤维化聚集[2]．

iii．在PD病人LBs内，Ub通过赖氨酸残基-63（Lys-63）共价结合于α-SYN的2个泛素化修饰位点，即，Lys-10和Lys-12[2]．Ub与α-SYN一样也是LBs的特征蛋白质成分[8]．Ub在LBs内的存在形式是Ub单体、2分子Ub单位（一个Ub的C末端甘氨酸残基的羧基与另外一个Ub的Lys-48的ε-氨基通过异肽键形成的二肽）乃至多分子Ub单位（或Ub链）．蛋白质泛素化修饰促进α-SYN进行纤维化聚集[12]．在DLB病人LBs内，Ub样蛋白质修饰物（Ub-like protein modifiers，ULMs）异构体SUMO1（small Ub-like modifier

1）以类泛素化（sumoylation）修饰方式结合于α-SYN的N端某个Lys-（可能是Lys-102）[13]；在PD病人LBs内，ULMs异构体NEDD8（neural precursor cell-expresd, developmentally down-regulated protein）以同样方式结合于α-SYN的相同氨基酸残基位点[13]．蛋白质类泛素化修饰促进α-SYN进行纤维化聚集[2Asp-119、Tyr-133或Asp-135位点被物质代谢产生的自由基有选择地截断[2α-SYN进行纤维化聚集[2]．

v．在PD病人和DLB病人LBs内，α-SYN通过酶促催化反应形成分子内、间交联物[14]．可溶性组织，3]，3]．

iv．在DLB病人LBs内，α-SYN在天冬氨酸残基-115（Asp-115）、天冬酰胺残基-122（Asn-122）、．分子断裂使α-SYN失去了C端部分氨基酸序列，α-SYN由此减弱了分子伴侣活性和蛋白质结合作用．这种蛋白质化学修饰形式促进

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生物化学与生物物理进展 Prog. Biochem. Biophys.

型转谷氨酰胺酶（soluble tissue transglutamina，tTGa）催化谷氨酰胺（Gln）与Lys之间的转酰胺基反应[2]．在α-SYN内部和（或）α-SYN分子之间，tTGa催化Gln-79或Gln-109与N端区段一些Lys-（Lys-，8，14]的具体位置不清楚）之间以及Gln-79、Gln-99或Gln-109与Lys-60之间的转酰胺基反应，α-SYN借此形成分子内、间交联物[3]．在LBD病人LBs内，α-SYN通过非酶促催化反应形成分子内、间交联物[2．葡萄糖代谢和脂质过氧化产生的高反应性醛类物质通过自由基诱导的氧化还原反应广泛地在蛋白质Lys-位点形成高级糖基化终末产物（advanced glycation end-products，AGEs），AGEs之间相互作用使蛋白质形成交联物[2]．α-SYN极有可能通过上述非酶促催化反应在它的15个Lys-位点形成分子内、间交联物．蛋白质交联阻碍α-SYN形成完整的四级结构[2]．这种蛋白质化学修饰形式促进α-SYN进行非纤维化聚集[15-17]．

参 考 文 献

[1] Arawaka S, Wada M, Goto S, et al. The role of G-protein-coupled receptor kina 5 in pathogenesis of

sporadic Parkinson's dia. J Neurosci, 2006, 26(36):9227-9238.

[2] Breydo L, Wu JW, Uversky VN. Α-synuclein misfolding and Parkinson's dia. Biochim Biophys Acta,

2012, 1822(2): 261-285.

[3] Beyer K. Alpha-synuclein structure, posttranslational modification and alternative splicing as aggregation

enhancers. Acta Neuropathol, 2006, 112(3): 237-251.

[4] Reynolds MR, Berry RW, Binder LI. Nitration in neurodegeneration: deciphering the "Hows" "nYs".

Biochemistry, 2007, 46(25):7325-7336.

[5] Zhou W, Freed CR. Tyrosine-to-cysteine modification of human alpha-synuclein enhances protein aggregation

and cellular toxicity. J Biol Chem, 2004, 279(11):10128-10135.

[6] Zhou W, Long C, Reaney SH, et al. Methionine oxidation stabilizes non-toxic oligomers of alpha-synuclein

through strengthening the auto-inhibitory intra-molecular long-range interactions. Biochim Biophys Acta,

2010, 1802(3): 322-330.

[7] Uversky VN, Yamin G, Souillac PO, et al. Methionine oxidation inhibits fibrillation of human alpha-synuclein

in vitro. FEBS Lett, 2002, 517(1-3): 239-244.

[8] Dev KK, Hofele K, Barbieri S, et al. Part II: alpha-synuclein and its molecular pathophysiological role in

neurodegenerative dia. Neuropharmacology, 2003, 45(1): 14-44.

[9] Rochet JC, Outeiro TF, Conway KA, et al. Interactions among alpha-synuclein, dopamine, and biomembranes:

some clues for understanding neurodegeneration in Parkinson's dia. J Mol Neurosci, 2004, 23(1-2): 23-34.

[10] Herrera FE, Chesi A, Paleologou KE, et al. Inhibition of alpha-synuclein fibrillization by dopamine is

mediated by interactions with five C-terminal residues and with E83 in the NAC region. PLoS One, 2008,

3(10): e3394.

[11] Bisaglia M, Tosatto L, Munari F, et al. Dopamine quinones interact with alpha-synuclein to form unstructured

adducts. Biochem Biophys Res Commun, 2010, 394(2): 424-428.

[12] Tofaris GK, Razzaq A, Ghetti B, et al. Ubiquitination of alpha-synuclein in Lewy bodies is a pathological

event not associated with impairment of proteasome function. J Biol Chem, 2003, 278(45): 44405-444011.

[13] Dil Kuazi A, Kito K, Abe Y, et al. NEDD8 protein is involved in ubiquitinated inclusion bodies. J Pathol,

2003, 199(2): 259-266.

[14] Junn E, Ronchetti RD, Quezado MM, et al. Tissue transglutamina-induced aggregation of alpha-synuclein:

Implications for Lewy body formation in Parkinson's dia and dementia with Lewy bodies. Proc Natl Acad

Sci U S A, 2003, 100(4): 2047-2052.

[15] Münch G, Lüth HJ, Wong A, et al. Crosslinking of alpha-synuclein by advanced glycation endproducts-an

early pathophysiological step in Lewy body formation? J Chem Neuroanat, 2000, 20(3-4): 253-257.

生物化学与生物物理进展 Prog. Biochem. Biophys.

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[16] Schmid AW, Chiappe D, Pignat V, et al. Discting the mechanisms of tissue transglutamina-induced

cross-linking of alpha-synuclein: implications for the pathogenesis of Parkinson dia. J Biol Chem, 2009,

284(19): 13128-13142.

[17] Nemes Z, Petrovski G, Aerts M, et al. Transglutamina-mediated intramolecular cross-linking of

membrane-bound alpha-synuclein promotes amyloid formation in Lewy bodies. J Biol Chem, 2009, 284(40):

27252-27264.