Coexistence of Communicating and Noncommunicating Cells in the Filamentous Cyanobacterium Anabaena.
Coexistence of Communicating and Noncommunicating Cells in the Filamentous Cyanobacterium Anabaena.
复制标题
鱼腥藻中通讯细胞和非通讯细胞的共存。
DOI：
10.1128/msphere.01091-20
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发表时间：
2021-01-13
期刊：
影响因子：
4.8
通讯作者：
Flores E
中科院分区：
文献类型：
--
作者：
Arévalo S;Nenninger A;Nieves-Morión M;Herrero A;Mullineaux CW;Flores E
多细胞生物存在于细菌和真核生物中，丝状异囊形成（固定n2）蓝藻代表了一种简单而古老的多细胞生物范式。多细胞性通常涉及细胞间的粘附和通讯。在丝状异囊形成（n2固定）蓝藻中，间隔连接连接相邻细胞，介导细胞间通讯，并被认为通过纳米孔穿过间隔肽聚糖。利用荧光标记钙黄素进行光漂白后荧光恢复（FRAP）分析表明，在复合氮存在下培养的Anabaena sp.菌株PCC 7120含有大量的非交流细胞（分别占硝酸盐和氨培养中所测试的营养细胞的58%和80%），而诱导固氮培养中含有的非交流细胞要少得多（16%）。一个单丝可以有通讯细胞和非通讯细胞。这些观察结果表明，细胞中所有（或大部分）间隔连接都可以协调调节，并且与细胞间通信的需要一致，特别是在重氮营养条件下。一致地，细胞间交换对氮剥夺的响应增加，而对培养基中铵的存在或硝酸盐同化的响应迅速减少。在Anabaena中已经发现了参与隔膜连接形成的蛋白质，包括SepJ、FraC和FraD。在这里，我们重新评估了钙黄蛋白的细胞间转移率和缺乏这些蛋白质的突变体的纳米孔数量，发现只有在固氮诱导的培养物中，这两个参数之间存在很强的正相关。因此，尽管大量非通讯细胞的存在似乎削弱了这种相关性，但重氮培养中获得的数据支持纳米孔是保持间隔连接的结构的观点。多细胞生物存在于细菌和真核生物中，丝状异囊形成（固定n2）蓝藻代表了一种简单而古老的多细胞生物范式。多细胞性通常涉及细胞间的粘附和通讯。蓝藻细丝中的细胞通过蛋白间隔连接连接，介导分子扩散。间隔连接穿过间隔肽聚糖，其中有称为纳米孔的孔。我们的研究结果表明，细胞内的隔膜连接可以被协调调节，并强调了隔膜连接和纳米孔之间的关系，以建立细胞间的通信结构，这是形成异囊蓝藻的多细胞行为所必需的。
Multicellularity is found in bacteria as well as in eukaryotes, and the filamentous heterocyst-forming (N2-fixing) cyanobacteria represent a simple and ancient paradigm of multicellular organisms. Multicellularity generally involves cell-cell adhesion and communication. In filamentous heterocyst-forming (N2-fixing) cyanobacteria, septal junctions join adjacent cells, mediating intercellular communication, and are thought to traverse the septal peptidoglycan through nanopores. Fluorescence recovery after photobleaching (FRAP) analysis with the fluorescent marker calcein showed that cultures of Anabaena sp. strain PCC 7120 grown in the presence of combined nitrogen contained a substantial fraction of noncommunicating cells (58% and 80% of the tested vegetative cells in nitrate- and ammonium-grown cultures, respectively), whereas cultures induced for nitrogen fixation contained far fewer noncommunicating cells (16%). A single filament could have communicating and noncommunicating cells. These observations indicate that all (or most of) the septal junctions in a cell can be coordinately regulated and are coherent with the need for intercellular communication, especially under diazotrophic conditions. Consistently, intercellular exchange was observed to increase in response to N deprivation and to decrease rapidly in response to the presence of ammonium in the medium or to nitrate assimilation. Proteins involved in the formation of septal junctions have been identified in Anabaena and include SepJ, FraC, and FraD. Here, we reevaluated rates of intercellular transfer of calcein and the number of nanopores in mutants lacking these proteins and found a strong positive correlation between the two parameters only in cultures induced for nitrogen fixation. Thus, whereas the presence of a substantial number of noncommunicating cells appears to impair the correlation, data obtained in diazotrophic cultures support the idea that the nanopores are the structures that hold the septal junctions. IMPORTANCE Multicellularity is found in bacteria as well as in eukaryotes, and the filamentous heterocyst-forming (N2-fixing) cyanobacteria represent a simple and ancient paradigm of multicellular organisms. Multicellularity generally involves cell-cell adhesion and communication. The cells in the cyanobacterial filaments are joined by proteinaceous septal junctions that mediate molecular diffusion. The septal junctions traverse the septal peptidoglycan, which bears holes termed nanopores. Our results show that the septal junctions can be coordinately regulated in a cell and emphasize the relationship between septal junctions and nanopores to build intercellular communication structures, which are essential for the multicellular behavior of heterocyst-forming cyanobacteria.