An ORFan no more: the bacteriophage T4 39.2 gene product, NwgI, modulates GroEL chaperone function.
An ORFan no more: the bacteriophage T4 39.2 gene product, NwgI, modulates GroEL chaperone function.
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DOI：
10.1534/genetics.111.135640
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发表时间：
2012-03
期刊：
影响因子：
3.3
通讯作者：
Georgopoulos C
中科院分区：
文献类型：
--
作者：
Ang D;Georgopoulos C
噬菌体是我们生物圈中最丰富的生物实体，其特点是其超可塑性，马赛克组成，以及由其巨大的遗传库编码的许多未知功能（orfan）。这些基因可能由噬菌体维持，以便在自然界中遇到的宿主上有效繁殖。为了验证这一假设，我们设计了一种选择来鉴定噬菌体编码的基因，这些基因可以调节宿主大肠杆菌GroEL/GroES伴侣蛋白，这对于某些宿主和噬菌体蛋白的折叠是必不可少的。结果，我们鉴定出了先前未知功能的噬菌体RB69基因39.2，并发现在T4、RB43和RB49噬菌体中39.2的同源物类似地调节GroEL/GroES。野生型噬菌体T4 Gp39.2（一种58个氨基酸的蛋白）的产生(a)使不同的噬菌体能够以等位基因特异性的方式在不允许的groES或groEL突变体宿主上形成斑块，(b)抑制groES和groEL突变体的温度敏感表型，(c)抑制groEL44突变体有缺陷的紫外线诱导的PolV功能（UmuCD）， (d)过量生产时对宿主是致命的。最后，为了证明Gp39.2是噬菌体在某些细菌宿主上生长所必需的原理，我们构建了T4 39.2缺失菌株，并表明，与等基因野生型亲本不同，它不能在某些groEL突变宿主上繁殖。我们提出了Gp39.2如何调节GroES/GroEL功能的模型。
Bacteriophages are the most abundant biological entities in our biosphere, characterized by their hyperplasticity, mosaic composition, and the many unknown functions (ORFans) encoded by their immense genetic repertoire. These genes are potentially maintained by the bacteriophage to allow efficient propagation on hosts encountered in nature. To test this hypothesis, we devised a selection to identify bacteriophage-encoded gene(s) that modulate the host Escherichia coli GroEL/GroES chaperone machine, which is essential for the folding of certain host and bacteriophage proteins. As a result, we identified the bacteriophage RB69 gene 39.2, of previously unknown function and showed that homologs of 39.2 in bacteriophages T4, RB43, and RB49 similarly modulate GroEL/GroES. Production of wild-type bacteriophage T4 Gp39.2, a 58-amino-acid protein, (a) enables diverse bacteriophages to plaque on the otherwise nonpermissive groES or groEL mutant hosts in an allele-specific manner, (b) suppresses the temperature-sensitive phenotype of both groES and groEL mutants, (c) suppresses the defective UV-induced PolV function (UmuCD) of the groEL44 mutant, and (d) is lethal to the host when overproduced. Finally, as proof of principle that Gp39.2 is essential for bacteriophage growth on certain bacterial hosts, we constructed a T4 39.2 deletion strain and showed that, unlike the isogenic wild-type parent, it is incapable of propagating on certain groEL mutant hosts. We propose a model of how Gp39.2 modulates GroES/GroEL function.