Dissociation of cytochrome c from liposomes by histone H1. Comparison with basic peptides.
Dissociation of cytochrome c from liposomes by histone H1. Comparison with basic peptides.
复制标题
组蛋白 H1 将细胞色素 c 从脂质体中解离。
DOI：
10.1021/bi952413w
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发表时间：
1996
期刊：
影响因子：
2.9
通讯作者：
P. Kinnunen
中科院分区：
文献类型：
--
作者：
M. Rytömaa;P. Kinnunen
碱性染色体蛋白质组蛋白H1与含有酸性磷脂的脂质体强烈结合，其特征有点类似于细胞色素c（cyt c）的脂质结合[Koiv et al.（1995）Biochemistry 34，8018-8027]。组蛋白H1的膜缔合强烈减弱含有磷脂酰甘油（PG）的大单层囊泡中的脂质侧向扩散，如通过含芘脂肪酸的磷脂衍生物1-棕榈酰基-2-[10-（芘-1-基）癸酰基]-sn-甘油基-3-磷酸甘油（PPDPG）荧光的激基缔合物与单体比率Ie/Im的降低所揭示的。类似地，由于组蛋白H1，膜结合探针二苯基己三烯（DPH）的荧光各向异性增加表明膜变得更加刚性。增加PG的摩尔分数（XPG）以线性方式增加Ie/Im最大降低或荧光各向异性增加所需的浓度[H1]s，从而允许估计H1的结合位点由约20个PG分子构成。域的形成也支持差示扫描量热法测量。随后，我们研究了从PG含有脂质体的细胞色素c的分离H1通过测量其效率，在减少PPDPG和血红素的细胞色素c之间的共振能量转移。1 μ M cyt c与25 μ M PG/PC（XPG = 0.20）脂质体的A位点相互作用被低浓度（0.1 μ M）组蛋白完全抑制。当XPG增加时，细胞色素c完全脱离所需的浓度[H1]D增加。不考虑[cyt c]的存在（在0.1和10 μ M之间变化），C位点介导的cyt c与纯PG脂质体（XPG = 1.0）的结合在[H1] = 0.6 μ M时完全被阻止。这些测量表明组蛋白H1对脂质体的亲和力超过了cyt c。随后将H1的上述作用与不同碱性膜结合肽的作用进行比较。值得注意的是，HI的效果被多聚赖氨酸（K19）显著良好地再现。H1对酸性磷脂的高亲和力表明，这一特征也可能有助于其生理功能。
The basic chromosomal protein histone H1 binds avidly to liposomes containing acidic phospholipids and with characteristics somewhat resembling the lipid association of cytochrome c (cyt c) [Koiv et al. (1995) Biochemistry 34, 8018-8027]. Membrane association of histone H1 strongly attenuates the lipid lateral diffusion in large unilamellar vesicles containing phosphatidylglycerol (PG) as revealed by the decrease in the excimer to monomer ratio Ie/Im of the pyrene fatty acid-containing phospholipid derivative 1-palmitoyl-2-[10-(pyren-1-yl)decanoyl]-sn-glycero-3-phosphogly cer ol (PPDPG) fluorescence. Similarly, an increase in fluorescence anisotropy of the membrane-incorporated probe, diphenylhexatriene (DPH), due to histone H1 indicates that the membrane becomes more rigid. Increasing the mole fraction of PG (XPG) increases in a linear manner the concentration [H1]s required for the maximal decrease in Ie/Im or increase in fluorescence anisotropy, thus allowing to estimate the binding site for H1 to be constituted by approximately 20 PG molecules. Domain formation is also supported by differential scanning calorimetry measurements. Subsequently, we studied the detachment of cyt c from PG-containing liposomes by H1 by measuring its efficiency in decreasing resonance energy transfer between PPDPG and the heme of cyt c. The A-site interaction of 1 microM cyt c with 25 microM PG/PC (XPG = 0.20) liposomes is fully inhibited by low (0.1 microM) histone concentrations. Upon XPG being increased, the concentration [H1]D required for complete detachment of cyt c increases. Irrespective of the [cyt c] present (varying between 0.1 and 10 microM), the C-site-mediated binding of cyt c to neat PG liposomes (XPG = 1.0) is fully prevented at [H1] = 0.6 microM. These measurements indicate that the affinity of histone H1 to liposomes exceeds that of cyt c. The above effects of H1 were subsequently compared with those of different basic membrane-associating peptides. Notably, the effects of HI were remarkably well-reproduced by polylysine (K19). The high affinity of H1 to acidic phospholipids suggests that this feature might also contribute to its physiological function.