Light regulation of type IV pilus-dependent motility by chemosensor-like elements in Synechocystis PCC6803
Light regulation of type IV pilus-dependent motility by chemosensor-like elements in Synechocystis PCC6803
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DOI：
10.1073/pnas.131201098
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发表时间：
2001-06-19
影响因子：
11.1
通讯作者：
Grossman, AR
中科院分区：
文献类型：
--
作者：
Bhaya, D;Takahashi, A;Grossman, AR
为了优化光合作用，蓝细菌通过一种被称为趋光性的过程朝向或远离光源移动。蓝藻集胞藻PCC 6803的趋光运动是一种表面依赖性现象，需要IV型皮利，涉及抽搐和社会运动的一系列细菌的细胞附属物。为了阐明蓝藻运动的调节，我们产生了转座子标记的突变体与异常趋光性;突变体是nonmotile或相对于野生型细胞表现出“反向运动反应”（负趋光性）。几个突变体含有转座子的基因类似于那些参与细菌的趋化性，集胞藻PCC 6803有三个位点的趋化性样基因，其中两个，Tax 1和Tax 3，参与趋光性。转座子中断出租车位点产生的突变体，表现出反向运动反应，这表明该位点参与控制积极的趋光性。然而，一个菌株无效的taxAY 1是nonmotile和hyperpilial。有趣的是，虽然TaxD 1多肽的C-末端区域类似于肠甲基接受化学受体蛋白的信号传导结构域，但N末端具有两个类似于光敏色素（植物中的光感受器）的发色团结合结构域的结构域。因此，TaxD 1可能在感知光刺激中起作用。Tax 3基因座的突变体是不动的，不产生IV型菌毛，这些发现建立了趋化性样调控元件和IV型菌毛介导的趋光性之间的联系。
To optimize photosynthesis, cyanobacteria move toward or away from a light source by a process known as phototaxis. Phototactic movement of the cyanobacterium Synechocystis PCC6803 is a surface-dependent phenomenon that requires type IV pili, cellular appendages implicated in twitching and social motility in a range of bacteria. To elucidate regulation of cyanobacterial motility, we generated transposon-tagged mutants with aberrant phototaxis; mutants were either nonmotile or exhibited an "inverted motility response" (negative phototaxis) relative to wild-type cells. Several mutants contained transposons in genes similar to those involved in bacterial chemotaxis, Synechocystis PCC6803 has three loci with chemotaxis-like genes, of which two, Tax1 and Tax3, are involved in phototaxis. Transposons interrupting the Taxi locus yielded mutants that exhibited an inverted motility response, suggesting that this locus is involved in controlling positive phototaxis. However, a strain null for taxAY1 was nonmotile and hyperpiliated. Interestingly, whereas the C-terminal region of the TaxD1 polypeptide is similar to the signaling domain of enteric methyl-accepting chemoreceptor proteins, the N terminus has two domains resembling chromophore-binding domains of phytochrome, a photoreceptor in plants. Hence, TaxD1 may play a role in perceiving the light stimulus. Mutants in the Tax3 locus are nonmotile and do not make type IV pill, These findings establish links between chemotaxis-like regulatory elements and type IV pilus-mediated phototaxis.