Lipoprotein Sorting Signals Evaluated as the LolA-dependent Release of Lipoproteins from the Cytoplasmic Membrane of Escherichia coli *
Lipoprotein Sorting Signals Evaluated as the LolA-dependent Release of Lipoproteins from the Cytoplasmic Membrane of Escherichia coli *
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通过 LolA 依赖性从大肠杆菌细胞质膜释放脂蛋白来评估脂蛋白分选信号*
DOI：
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发表时间：
2001
影响因子：
4.8
通讯作者：
H. Tokuda
中科院分区：
文献类型：
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作者：
M. Terada;Toshiro Kuroda;S. Matsuyama;H. Tokuda
大肠杆菌脂蛋白通过与N端半胱氨酸共价连接的脂肪酰链锚定在内膜或外膜上。天冬氨酸在位置2的功能是将脂蛋白保留在内膜中，尽管这种保留受到位置3的残基的干扰。我们先前揭示了LolCDE和LOLA在这种脂蛋白分类中起着关键作用。为了阐明分选信号，在球形体中检测了具有不同残基的脂蛋白衍生物在球体中的依赖于LOLA的释放。当3位残基为丝氨酸时，只有2位天冬氨酸导致脂蛋白滞留在球体中。然后我们研究了天冬氨酸在2位和各种残基在3位的衍生物的释放。在3位有少量残基的情况下发生了很强的内膜保留。这些残基存在于天冬氨酸在2位的天然脂蛋白的3位，而抑制这种保留的残基不存在。研究还发现，2位和3位残基的结合可以形成除天冬氨酸以外的2位残基的强内膜保留信号。这些结果表明，天然脂蛋白的内膜定位是通过使用有限数量的强内膜保留信号来保证的。
Escherichia coli lipoproteins are anchored to either the inner or outer membrane through fatty acyl chains covalently attached to an N-terminal cysteine. Aspartate at position 2 functions to retain lipoproteins in the inner membrane, although the retention is perturbed depending on the residue at position 3. We previously revealed that LolCDE and LolA play critical roles in this lipoprotein sorting. To clarify the sorting signals, the LolA-dependent release of lipoprotein derivatives having various residues at positions 2 and 3 was examined in spheroplasts. When the residue at position 3 was serine, only aspartate at position 2 caused the retention of lipoproteins in spheroplasts. We then examined the release of derivatives having aspartate at position 2 and various residues at position 3. Strong inner membrane retention occurred with a limited number of species of residues at position 3. These residues were present at position 3 of native lipoproteins having aspartate at position 2, whereas residues that inhibited the retention were not. It was also found that a strong inner membrane retention signal having residues other than aspartate at position 2 could be formed through the combination of the residues at positions 2 and 3. These results indicate that the inner membrane localization of native lipoproteins is ensured by the use of a limited number of strong inner membrane retention signals.