Global Regulation of Gene Expression and Cell Differentiation in Caulobacter crescentus in Response to Nutrient Availability
Global Regulation of Gene Expression and Cell Differentiation in Caulobacter crescentus in Response to Nutrient Availability
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DOI：
10.1128/jb.01240-09
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发表时间：
2010-02-01
影响因子：
3.2
通讯作者：
Gober, James W.
中科院分区：
文献类型：
--
作者：
England, Jennifer C.;Perchuk, Barrett S.;Gober, James W.
在一种旨在有效利用稀少营养环境并在其上定居的发展战略中，新月桂杆菌细胞不对称分裂，产生一个活动的集群细胞和一个固着的柄细胞。在典型的培养条件下，经过一段相对固定的时间后，沼泽细胞分化为可复制的柄细胞。由于分化为柄细胞类型是不可逆的，环境因素，如必需营养素的可获得性，很可能会影响放弃活动和采取固执生活方式的决定的时机。我们在营养限制的恒化器培养中测量了两个不同的参数，生物量浓度和无柄细胞与有柄细胞的比率，在一定的流速范围内，我们发现氮素限制显著延长了沼泽细胞的寿命。这里描述的转录图谱实验第一次全面地描绘了在关键常量营养素稀少的环境中，寡养菌所使用的全球调控策略。在氮和碳限制的细胞中，受调控的基因表达模式与大多数共营养生物有一些共同的特征，但关键的差异表明，硫杆菌，也许还有其他寡养生物，已经进化出调控策略，以明显地处理他们的自然环境。我们假设，氮素限制通过延迟一系列分化事件的开始来延长沼泽细胞的寿命，当外部环境线索的正确组合启动时，氮素限制将使沼泽细胞在固定的时间段内分化为有柄的细胞。
In a developmental strategy designed to efficiently exploit and colonize sparse oligotrophic environments, Caulobacter crescentus cells divide asymmetrically, yielding a motile swarmer cell and a sessile stalked cell. After a relatively fixed time period under typical culture conditions, the swarmer cell differentiates into a replicative stalked cell. Since differentiation into the stalked cell type is irreversible, it is likely that environmental factors such as the availability of essential nutrients would influence the timing of the decision to abandon motility and adopt a sessile lifestyle. We measured two different parameters in nutrient-limited chemostat cultures, biomass concentration and the ratio of nonstalked to stalked cells, over a range of flow rates and found that nitrogen limitation significantly extended the swarmer cell life span. The transcriptional profiling experiments described here generate the first comprehensive picture of the global regulatory strategies used by an oligotroph when confronted with an environment where key macronutrients are sparse. The pattern of regulated gene expression in nitrogen- and carbon-limited cells shares some features in common with most copiotrophic organisms, but critical differences suggest that Caulobacter, and perhaps other oligotrophs, have evolved regulatory strategies to deal distinctly with their natural environments. We hypothesize that nitrogen limitation extends the swarmer cell lifetime by delaying the onset of a sequence of differentiation events, which when initiated by the correct combination of external environmental cues, sets the swarmer cell on a path to differentiate into a stalked cell within a fixed time period.