Hughes D S, Felbeck H, Stein J L
Marine Biology Research Division, Scripps Institution of Oceanography, La Jolla, California 92093-0202, USA.
Appl Environ Microbiol. 1997 Sep;63(9):3494-8. doi: 10.1128/aem.63.9.3494-3498.1997.
The uncultivated bacterial endosymbionts of the hydrothermal vent tubeworm Riftia pachyptila play a central role in providing their host with fixed carbon. While this intimate association between host and symbiont indicates tight integration and coordination of function via cellular communication mechanisms, no such systems have been identified. To elucidate potential signal transduction pathways in symbionts that may mediate symbiont-host communication, we cloned and characterized a gene encoding a histidine protein kinase homolog isolated from a symbiont fosmid library. The gene, designated rssA (for Riftia symbiont signal kinase), resembles known sensor kinases and encodes a protein capable of phosphorylating response regulators in Escherichia coli. A second open reading frame, rssB (for Riftia symbiont signal regulator), encodes a protein similar to known response regulators. These results suggest that the symbionts utilize a phosphotransfer signal transduction mechanism to communicate external signals that may mediate recognition of or survival within the host. The specific signals eliciting a response by the signal transduction proteins of the symbiont remain to be elucidated.
热液喷口管虫厚壳贻贝（Riftia pachyptila）未培养的细菌内共生体在为宿主提供固定碳方面发挥着核心作用。虽然宿主与共生体之间的这种紧密联系表明通过细胞通讯机制实现了功能的紧密整合与协调，但尚未鉴定出这样的系统。为了阐明共生体中可能介导共生体与宿主通讯的潜在信号转导途径，我们从共生体fosmid文库中克隆并鉴定了一个编码组氨酸蛋白激酶同源物的基因。该基因命名为rssA（代表厚壳贻贝共生体信号激酶），类似于已知的传感器激酶，编码一种能够在大肠杆菌中磷酸化应答调节因子的蛋白质。第二个开放阅读框rssB（代表厚壳贻贝共生体信号调节因子）编码一种类似于已知应答调节因子的蛋白质。这些结果表明，共生体利用磷酸转移信号转导机制来传递可能介导在宿主内识别或生存的外部信号。引发共生体信号转导蛋白应答的具体信号仍有待阐明。
