Biased inheritance of the protein PatN frees vegetative cells to initiate patterned heterocyst differentiation
Biased inheritance of the protein PatN frees vegetative cells to initiate patterned heterocyst differentiation
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DOI：
10.1073/pnas.1207530109
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发表时间：
2012-09-18
影响因子：
11.1
通讯作者：
Meeks, John C.
中科院分区：
文献类型：
--
作者：
Risser, Douglas D.;Wong, Francis C. Y.;Meeks, John C.
异形胞，在某些丝状蓝藻中专门用于固氮的细胞，沿着营养细胞链沿着以非随机间隔模式单独出现。一个两阶段的，有偏见的启动和竞争决议模型已被提出来解释这种间距模式的建立。有大量的证据表明，竞争性决议的一个子集的细胞启动分化发生之间的相互作用的自我增强激活蛋白，HetR，和扩散性五肽抑制剂PatS-5（RGSGR）。这里提出的结果表明，没有一个独特的膜蛋白，PatN，在念珠藻菌株ATCC 29133导致异形胞频率增加三倍，异形胞之间的营养细胞间隔减少四倍。PatN-GFP的翻译融合显示了在铵生长培养物的子代营养细胞中偏向遗传的模式。另一个异形胞图案基因，patA，失活是上位失活patN，和patA的转录增加patN缺失菌株，这意味着patN可能通过调节patA的水平发挥作用。假设PatN的存在降低营养细胞启动异形胞分化的能力，并且PatN的细胞浓度依赖于导致细胞瞬时耗尽PatN的细胞分裂。我们认为，有偏见的遗传细胞命运的决定因素是一个系统发育域跨越范式的发展生物模式。
Heterocysts, cells specialized for nitrogen fixation in certain filamentous cyanobacteria, appear singly in a nonrandom spacing pattern along the chain of vegetative cells. A two-stage, biased initiation and competitive resolution model has been proposed to explain the establishment of this spacing pattern. There is substantial evidence that competitive resolution of a subset of cells initiating differentiation occurs by interactions between a self-enhancing activator protein, HetR, and a diffusible pentapeptide inhibitor PatS-5 (RGSGR). Results presented here show that the absence of a unique membrane protein, PatN, in Nostoc punctiforme strain ATCC 29133 leads to a threefold increase in heterocyst frequency and a fourfold decrease in the vegetative cell interval between heterocysts. A PatN-GFP translational fusion shows a pattern of biased inheritance in daughter vegetative cells of ammonium-grown cultures. Inactivation of another heterocyst patterning gene, patA, is epistatic to inactivation of patN, and transcription of patA increases in a patN-deletion strain, implying that patN may function by modulating levels of patA. The presence of PatN is hypothesized to decrease the competency of a vegetative cell to initiate heterocyst differentiation, and the cellular concentration of PatN is dependent on cell division that results in cells transiently depleted of PatN. We suggest that biased inheritance of cell-fate determinants is a phylogenetic domain-spanning paradigm in the development of biological patterns.