Regulation of Sporangium Formation, Spore Dormancy, and Sporangium Dehiscence by a Hybrid Sensor Histidine Kinase in Actinoplanes missouriensis: Relationship with the Global Transcriptional Regulator TcrA
Regulation of Sporangium Formation, Spore Dormancy, and Sporangium Dehiscence by a Hybrid Sensor Histidine Kinase in Actinoplanes missouriensis: Relationship with the Global Transcriptional Regulator TcrA
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DOI：
10.1128/jb.00228-20
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发表时间：
2020-11-01
影响因子：
3.2
通讯作者：
Ohnishi, Yasuo
中科院分区：
文献类型：
--
作者：
Hashiguchi, Yuichiro;Tezuka, Takeaki;Ohnishi, Yasuo
罕见的放线菌密苏里放线菌形成末端孢子囊，含有几百个鞭毛孢子。作为对水的反应，孢子囊打开并将孢子释放到外部环境中。孤儿反应调节剂TcrA在孢子囊形成和破裂过程中起全局转录激活剂的作用。在这里，我们报告了孤儿杂交组氨酸激酶HhkA的特性。一个hhkA缺失突变体的孢子囊在诱导孢子囊破裂的条件下含有许多变形或异位萌发的孢子，孢子几乎不打开释放。这些表型变化与在tcrA缺失突变体中观察到的非常相似。比较RNA测序分析显示，HhkA控制的基因大部分与tra调控的基因重叠。细菌双杂交实验表明HhkA和TcrA之间存在直接的相互作用，但这并不是决定性的。在电泳迁移迁移实验中，乙酰磷酸作为磷酸供体对TcrA的磷酸化显著增强了其对TcrA盒序列的亲和力。结合这些观察结果，我们提出HhkA和TcrA构成同源的双组分调控系统，该系统控制着密苏里杉孢子囊形成、孢子休眠和孢子囊破裂等形态学发育过程中相关基因的转录。密苏里活动平面经历了复杂的形态分化，包括含鞭毛孢子的孢子囊的形成、孢子囊的开裂、游动孢子的游动以及游动孢子萌发到丝状生长。尽管孤儿反应调节因子TcrA在全球范围内激活了孢子囊形成、孢子休眠和孢子囊破裂所需的许多基因，但其伙伴组氨酸激酶仍然未知。在此，我们分析了孤儿杂交组氨酸激酶HhkA的功能，并提出HhkA与TcrA构成同源双组分调控系统。HhkA和TcrA同源物在Actirtoplanes属和几种密切相关的稀有放线菌中高度保守，表明这种可能的双组分调控系统被用于形成孢子囊和/或游动孢子的稀有放线菌的复杂形态发育。
The rare actinomycete Actinoplanes missouriensis forms terminal sporangia containing a few hundred flagellated spores. In response to water, the sporangia open and release the spores into external environments. The orphan response regulator TcrA functions as a global transcriptional activator during sporangium formation and dehiscence. Here, we report the characterization of an orphan hybrid histidine kinase, HhkA. Sporangia of an hhkA deletion mutant contained many distorted or ectopically germinated spores and scarcely opened to release the spores under sporangium dehiscence-inducing conditions. These phenotypic changes are quite similar to those observed in a tcrA deletion mutant. Comparative RNA sequencing analysis showed that genes controlled by HhkA mostly overlap TcrA-regulated genes. The direct interaction between HhkA and TcrA was suggested by a bacterial two-hybrid assay, but this was not conclusive. The phosphorylation of TcrA using acetyl phosphate as a phosphate donor markedly enhanced its affinity for the TcrA box sequences in the electrophoretic mobility shift assay. Taking these observations together with other results, we proposed that HhkA and TcrA compose a cognate two-component regulatory system, which controls the transcription of the genes involved in many aspects of morphological development, including sporangium formation, spore dormancy, and sporangium dehiscence in A. missouriensis.IMPORTANCE Actirtoplanes missouriensis goes through complex morphological differentiation, including formation of flagellated spore-containing sporangia, sporangium dehiscence, swimming of zoospores, and germination of zoospores to filamentous growth. Although the orphan response regulator TcrA globally activates many genes required for sporangium formation, spore dormancy, and sporangium dehiscence, its partner histidine kinase remained unknown. Here, we analyzed the function of an orphan hybrid histidine kinase, HhkA, and proposed that HhkA constitutes a cognate two-component regulatory system with TcrA. That HhkA and TcrA homologues are highly conserved among the genus Actirtoplanes and several closely related rare actinomycetes indicates that this possible two-component regulatory system is employed for complex morphological development in sporangium- and/or zoospore-forming rare actinomycetes.