Biochimica et Biophysica Acta (BBA) - General Subjects ( IF 3 ) Pub Date : 2020-09-15 , DOI: 10.1016/j.bbagen.2020.129732 Ivo Díaz Ludovico 1 , Romina A Gisonno 1 , Marina C Gonzalez 1 , Horacio A Garda 1 , Nahuel A Ramella 1 , M Alejandra Tricerri 1
Background
The identification of dysfunctional human apolipoprotein A-I (apoA-I) in atherosclerotic plaques suggests that protein structure and function may be hampered under a chronic pro inflammatory scenario. Moreover, the fact that natural mutants of this protein elicit severe cardiovascular diseases (CVD) strongly indicates that the native folding could shift due to the mutation, yielding a structure more prone to misfold or misfunction. To understand the events that determine the failure of apoA-I structural flexibility to fulfill its protective role, we took advantage of the study of a natural variant with a deletion of the residue lysine 107 (K107del) associated with atherosclerosis.
Methods
Biophysical approaches, such as electrophoresis, fluorescence and spectroscopy were used to characterize proteins structure and function, either in native conformation or under oxidation or intramolecular crosslinking.
Results
K107del structure was more flexible than the protein with the native sequence (Wt) but interactions with artificial membranes were preserved. Instead, structural restrictions by intramolecular crosslinking impaired the Wt and K107del lipid solubilization function. In addition, controlled oxidation decreased the yield of the native dimer conformation for both variants.
Conclusions
We conclude that even though mutations may alter protein structure and spatial arrangement, the highly flexible conformation compensates the mild shift from the native folding. Instead, post translational apoA-I modifications (probably chronic and progressive) are required to raise a protein conformation with significant loss of function and increased aggregation tendency.
General significance
The results learnt from this variant strength a close association between amyloidosis and atherosclerosis.
中文翻译:
了解载脂蛋白A-I在动脉粥样硬化中的作用。翻译后修饰能协同功能障碍吗?
背景
在动脉粥样硬化斑块中功能障碍的人类载脂蛋白AI(apoA-I)的鉴定表明,在慢性促炎性情况下,蛋白质的结构和功能可能受到阻碍。此外,该蛋白的天然突变体会引发严重的心血管疾病(CVD),这一事实强烈表明,由于该突变,天然折叠可能发生位移,从而产生了更易于错误折叠或功能失调的结构。为了了解决定apoA-I结构柔性无法实现其保护功能的事件,我们利用了天然变异体的研究,该变异体具有与动脉粥样硬化相关的残基赖氨酸107(K107del)缺失。
方法
使用生物物理方法,例如电泳,荧光和光谱学,以天然构象或在氧化或分子内交联下表征蛋白质的结构和功能。
结果
K107del结构比具有天然序列(Wt)的蛋白质更灵活,但与人工膜的相互作用得以保留。相反,分子内交联的结构限制削弱了Wt和K107del脂质增溶功能。另外,受控氧化降低了两个变体的天然二聚体构象的产率。
结论
我们得出的结论是,即使突变可能会改变蛋白质的结构和空间排列,但高度灵活的构象仍能弥补天然折叠带来的轻微变化。取而代之的是,需要翻译后的载脂蛋白A-1修饰(可能是慢性的和进行性的),以提高具有明显功能丧失和聚集趋势的蛋白质构象。
一般意义
从这种变异强度中学到的结果是淀粉样变性和动脉粥样硬化之间的紧密联系。