Temperature-Sensitive Growth and Decreased Thermotolerance Associated with relA Mutations in Escherichia coli
Temperature-Sensitive Growth and Decreased Thermotolerance Associated with relA Mutations in Escherichia coli
复制标题
大肠杆菌的温度敏感性生长和耐热性降低与 relA 突变相关
DOI：
10.1128/jb.185.19.5765-5771.2003
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发表时间：
2003
影响因子：
3.2
通讯作者：
E. Ishiguro
中科院分区：
文献类型：
--
作者：
Xiaoming Yang;E. Ishiguro
摘要 大肠杆菌的 relA 基因编码鸟苷 3',5'-双焦磷酸 (ppGpp) 合成酶 I，这是一种核糖体相关酶，在氨基酸饥饿期间被激活。严格反应被认为是由 ppGpp 介导的。已知 relA 突变会导致多效性表型。我们现在报道，三种不同的 relA 突变等位基因 relA1、relA2 和 relA251::kan 赋予温度敏感表型，如在温度高于 41°C 时营养琼脂 (Difco) 或戴维斯最小琼脂 (Difco) 上的铺板效率降低所证明的。 relA 介导的温度敏感性是渗透性的，可以完全抑制，例如，通过向培养基中添加浓度为 0.3 M 的 NaCl。relA 突变体的温度敏感性与耐热性降低有关；例如，relA 突变体在 42°C（通常是非致命的温度）下失去活力。 spoT 基因编码具有 ppGpp 合成酶和 ppGpp 焦磷酸水解酶活性的双功能酶。将 spoT207::cat 等位基因引入带有 relA251::kan 突变的菌株中，完全废除了 ppGpp 合成。这种 ppGpp 无效突变体比单独携带 relA251::kan 突变的菌株对温度更加敏感。 relA 介导的热敏感性受到 rpoB（编码 RNA 聚合酶 β 亚基）和 spoT 的某些突变等位基因的抑制，此前已报道这些突变等位基因可抑制 relA 突变赋予的其他表型特征。总的来说，这些结果表明 ppGpp 可能在某种程度上是耐热性相关基因表达所必需的。
ABSTRACT The relA gene of Escherichia coli encodes guanosine 3′,5′-bispyrophosphate (ppGpp) synthetase I, a ribosome-associated enzyme that is activated during amino acid starvation. The stringent response is thought to be mediated by ppGpp. Mutations in relA are known to result in pleiotropic phenotypes. We now report that three different relA mutant alleles, relA1, relA2, and relA251::kan, conferred temperature-sensitive phenotypes, as demonstrated by reduced plating efficiencies on nutrient agar (Difco) or on Davis minimal agar (Difco) at temperatures above 41°C. The relA-mediated temperature sensitivity was osmoremedial and could be completely suppressed, for example, by the addition of NaCl to the medium at a concentration of 0.3 M. The temperature sensitivities of the relA mutants were associated with decreased thermotolerance; e.g., relA mutants lost viability at 42°C, a temperature that is normally nonlethal. The spoT gene encodes a bifunctional enzyme possessing ppGpp synthetase and ppGpp pyrophosphohydrolase activities. The introduction of the spoT207::cat allele into a strain bearing the relA251::kan mutation completely abolished ppGpp synthesis. This ppGpp null mutant was even more temperature sensitive than the strain carrying the relA251::kan mutation alone. The relA-mediated thermosensitivity was suppressed by certain mutant alleles of rpoB (encoding the β subunit of RNA polymerase) and spoT that have been previously reported to suppress other phenotypic characteristics conferred by relA mutations. Collectively, these results suggest that ppGpp may be required in some way for the expression of genes involved in thermotolerance.
影响因子：
10.5
作者：
R. Vanbogelen;M. Acton;F. Neidhardt
通讯作者：
R. Vanbogelen;M. Acton;F. Neidhardt
影响因子：
10.5
作者：
GROSSMAN, AD;STRAUS, DB;GROSS, CA
通讯作者：
GROSS, CA
DOI：
10.1073/pnas.87.15.5589
发表时间：
1990-08-01
影响因子：
11.1
作者：
VANBOGELEN, RA;NEIDHARDT, FC
通讯作者：
NEIDHARDT, FC