Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, CT 06030-3305, USA.
J Bacteriol. 2011 Sep;193(18):4664-71. doi: 10.1128/JB.05343-11. Epub 2011 Jul 1.
Rates of commitment to germinate and germination of Bacillus subtilis spores with mixtures of low concentrations of germinants acting on different germinant receptors (GRs) were much higher than the sums of the rates of commitment and germination with individual germinants alone. This synergism with mixtures of nutrient germinants was not seen with spores lacking GRs responsible for recognizing one or several components of the germinant mixtures and was not eliminated by either a gerD mutation or overexpression of one of the GRs involved in this synergism. This synergism was also not seen between the germinant L-valine, which acts via a GR, and the germinant dodecylamine, which does not act via any GR. These results indicate that spores not only integrate but can also amplify signals from multiple germinants and multiple GRs in determining rates of commitment and overall spore germination. This amplification can be explained by a simple mechanism in which a single signal integrator triggers germination above an accumulation threshold. Direct cooperative action between GRs may further add to the synergism seen in germination triggered by multiple GRs. Further experiments and modeling are required to determine the relative contributions of these different mechanisms.
用作用于不同发芽受体 (GR) 的低浓度发芽混合物处理枯草芽孢杆菌孢子的发芽和发芽率比单独使用单个发芽剂的发芽和发芽率的总和要高得多。这种与营养发芽混合物的协同作用在缺乏负责识别发芽混合物中一种或几种成分的 GR 的孢子中没有出现，并且不会被 gerD 突变或涉及这种协同作用的 GR 之一的过表达消除。发芽剂 L-缬氨酸（通过 GR 起作用）和发芽剂十二胺（不通过任何 GR 起作用）之间也没有观察到这种协同作用。这些结果表明，孢子不仅可以整合，还可以放大来自多个发芽剂和多个 GR 的信号，以确定发芽率和整体孢子发芽率。这种放大可以通过一种简单的机制来解释，其中单个信号整合器在积累阈值之上触发发芽。GR 之间的直接协同作用可能会进一步增加多个 GR 触发的发芽协同作用。需要进一步的实验和建模来确定这些不同机制的相对贡献。
