The cyanobacterial taxis protein HmpF regulates type IV pilus activity in response to light
The cyanobacterial taxis protein HmpF regulates type IV pilus activity in response to light
复制标题
DOI：
10.1073/pnas.2023988118
复制
发表时间：
2021-03-23
影响因子：
11.1
通讯作者：
Risser, Douglas D.
中科院分区：
文献类型：
--
作者：
Harwood, Thomas, V;Zuniga, Esthefani G.;Risser, Douglas D.
运动在包括光合蓝藻在内的原核生物中是普遍存在的，其中由4型菌毛（T4P）驱动的表面运动是常见的，并促进趋光性以寻找有利的光环境。在蓝藻中，类趋化系统被认为可以调节运动和趋光性。表征的趋光系统依赖于甲基接受趋化蛋白，这些趋化蛋白含有能够直接感知光的十亿素结合GAF结构域，它们调节T4P的机制在很大程度上尚不明确。在这项研究中，我们证明了蓝藻具有第二种，gaf独立的，感应光来调节运动的手段，并提供了对趋化样系统如何调节T4P马达的见解。遗传学、细胞学和蛋白质-蛋白质相互作用分析的结合，以及使用质子离子载体羰基氰化物间氯苯肼的实验表明，模式丝状蓝藻Nostoc点状藻的Hmp类趋化系统能够间接地感知光，可能是通过改变质子动力，并调节蓝藻趋化蛋白HmpF和Hfq、PilT1之间的直接相互作用。和PilT2来调节T4P电机。考虑到Hmp系统在蓝藻中广泛保守，并且本研究发现来自远亲模型单细胞蓝藻Synechocystis sp.菌株PCC6803的HmpF和T4P蛋白的同源物以类似的方式相互作用，这可能代表了蓝藻中对光响应调节运动的普遍手段。
Motility is ubiquitous in prokaryotic organisms including the photosynthetic cyanobacteria where surface motility powered by type 4 pili (T4P) is common and facilitates phototaxis to seek out favorable light environments. In cyanobacteria, chemotaxis-like systems are known to regulate motility and phototaxis. The characterized phototaxis systems rely on methyl-accepting chemotaxis proteins containing bilin-binding GAF domains capable of directly sensing light, and the mechanism by which they regulate the T4P is largely undefined. In this study we demonstrate that cyanobacteria possess a second, GAF-independent, means of sensing light to regulate motility and provide insight into how a chemotaxis-like system regulates the T4P motors. A combination of genetic, cytological, and protein-protein interaction analyses, along with experiments using the proton ionophore carbonyl cyanide m-chlorophenyl hydrazine, indicate that the Hmp chemotaxis-like system of the model filamentous cyanobacterium Nostoc punctiforme is capable of sensing light indirectly, possibly via alterations in proton motive force, and modulates direct interaction between the cyanobacterial taxis protein HmpF, and Hfq, PilT1, and PilT2 to regulate the T4P motors. Given that the Hmp system is widely conserved in cyanobacteria, and the finding from this study that orthologs of HmpF and T4P proteins from the distantly related model unicellular cyanobacterium Synechocystis sp. strain PCC6803 interact in a similar manner to their N. punctiforme counterparts, it is likely that this represents a ubiquitous means of regulating motility in response to light in cyanobacteria.