Salt Effects on the Structural and Thermodynamic Properties of a Group 3 LEA Protein Model Peptide
Salt Effects on the Structural and Thermodynamic Properties of a Group 3 LEA Protein Model Peptide
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DOI：
10.1021/bi200719s
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发表时间：
2011-08-23
期刊：
影响因子：
2.9
通讯作者：
Sakurai, Minoru
中科院分区：
文献类型：
--
作者：
Furuki, Takao;Shimizu, Tempei;Sakurai, Minoru
在干燥的细胞中隔离或隔离离子物种是第3组晚期胚胎发生丰富（G3 LEA）蛋白的假定功能之一。我们仍然缺乏关于G3 LEA蛋白及其特征性一级氨基酸序列，即，11-mer基序重复在盐存在下在缺水条件下表现。在目前的研究中，我们研究了盐的影响，作为水含量的函数的22-mer肽（PvLEA-22），由两个串联重复的共识11-mer基序的G3 LEA蛋白从P. vanderplanki幼虫的结构和热力学性质。圆二色谱（CD）和傅里叶变换红外（FT-IR）光谱的测量结果表明：（1）PvLEA-22在盐和不盐的水溶液中均呈无规卷曲; (2)干燥的PvLEA-22，无论是无盐的还是与NaCl或KCl混合的，大部分折叠为α-螺旋。(3)当用MgCl 2或CaCl 2干燥时，PvLEA-22既具有β-折叠结构，又具有无规卷曲。(4)Pv莱亚-22忠实地再现了天然莱亚蛋白响应于添加的盐的构象变化。此外，通过温度调制差示扫描量热法（TMDSC）测量，干燥的PvLEA-22被发现在环境温度下处于玻璃态，独立于存在的盐。在这些结果的基础上，我们讨论了内在的性质和假定的功能作用的G3 LEA蛋白在富盐条件下。
To sequestrate or scavenge ionic species in desiccated cells is one of the putative functions of group 3 late embryogenesis abundant (G3LEA) proteins. We still lack direct physicochemical information on how G3LEA proteins and their characteristic primary amino acid sequences, i.e., 11-mer motif repeats, behave in the presence of salts under water-deficit conditions. In the current study, we investigated salt effects as a function of water content on the structural and thermodynamic properties of the 22-mer peptide (PvLEA-22), consisting of two tandem repeats of the consensus 11-mer motif of G3LEA proteins from the larvae of P. vanderplanki. The results of circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopic measurements indicate four main points as follows: (1) PvLEA-22 is in random coils in the aqueous solutions with or without a salt. (2) Dried PvLEA-22, whether salt-free or mixed with NaCl or KCl, is largely folded as alpha-helix. (3) When dried with MgCl2 or CaCl2, PvLEA-22 adopts beta-sheet structure as well as random coil. (4) PvLEA-22 faithfully reproduces the conformational changes of the native LEA protein in response to added salts. Furthermore, through temperature-modulated differential scanning calorimetry (TMDSC) measurements, dried PvLEA-22 is found to be in the glassy state at ambient temperatures, independent of which salt is present. On the basis of these results, we discuss the intrinsic nature and putative functional roles of G3LEA proteins under salt-rich conditions.