Biosynthesis of circular proteins in plants
Biosynthesis of circular proteins in plants
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DOI：
10.1111/j.1365-313x.2007.03357.x
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发表时间：
2008-02-01
期刊：
影响因子：
7.2
通讯作者：
Anderson, Marilyn A.
中科院分区：
文献类型：
--
作者：
Gillon, Amanda D.;Saska, Ivana;Anderson, Marilyn A.
植物环肽是天然存在的环状蛋白的大家族，其由含有一个、两个或三个环肽结构域的线性前体产生。切除环肽结构域并连接游离N-和C-末端以产生环状肽的机制尚未阐明。在这里，我们调查生产的原型cyclotide kalata B1的前体Oak 1从非洲植物Oldenlandia affinis。免疫沉淀实验和MALDI-TOF质谱分析表明，O。affinis仅产生成熟的kalata B1，而转基因拟南芥、烟草和本塞姆氏烟草产生线性和圆形形式。当在环肽结构域的C-末端加工位点处的高度保守的天冬酰胺残基被丙氨酸或天冬氨酸残基取代时，或者当保守的C-末端三肽基序被截短时，不产生环状肽。我们提出，有两个处理途径在植物：一个产生成熟的cyclotide和其他产生的线性变体，最终不能环化。
Plant cyclotides are a large family of naturally occurring circular proteins that are produced from linear precursors containing one, two or three cyclotide domains. The mechanism of excision of the cyclotide domains and ligation of the free N- and C-termini to produce the circular peptides has not been elucidated. Here, we investigate production of the prototypic cyclotide kalata B1 from the precursor Oak1 from the African plant Oldenlandia affinis. Immunoprecipitation experiments and MALDI-TOF mass spectrometry analysis showed that O. affinis only produces mature kalata B1, whereas transgenic Arabidopsis thaliana, Nicotiana tabacum and Nicotiana benthamiana produced both linear and circular forms. Circular peptides were not produced when a highly conserved asparagine residue at the C-terminal processing site of the cyclotide domain was replaced with an alanine or an aspartate residue, or when the conserved C-terminal tripeptide motif was truncated. We propose that there are two processing pathways in planta: one to produce the mature cyclotide and the other to produce linear variants that ultimately cannot be cyclized.