Importance of Individual Germination Receptor Subunits in the Cooperative Function between GerA and Ynd
Importance of Individual Germination Receptor Subunits in the Cooperative Function between GerA and Ynd
复制标题
DOI：
10.1128/jb.00451-19
复制
发表时间：
2019-10-01
影响因子：
3.2
通讯作者：
Lindback, Toril
中科院分区：
文献类型：
--
作者：
Aspholm, Marina;Borch-Pedersen, Kristina;Lindback, Toril
芽孢杆菌孢子的萌发是通过特定营养物质与位于孢子内膜的萌发受体（GR）结合而触发的。GR通常由A、B和C亚基组成，由三顺反子格尔操纵子编码。地衣芽孢杆菌基因组包含gerA家族操纵子gerA、ynd和gerK。与许多芽孢杆菌属物种gerA操纵子的ABC（D）结构特征相反，B.地衣菌基因组含有五顺反子ynd操纵子，其包含yndD、yndE（3）、yndE（2）、yndF（1）和yndE（1），分别编码A、B、B、C和B GR亚基的基因（下标表示旁系同源物）。这里我们展示了B。地衣孢子可以在没有Ynd和GerK GR的情况下萌发，尽管所有三种GR之间的合作对于氨基酸的最佳萌发是必需的。孢子携带一套不完整的Ynd B亚基表现出降低的发芽效率，而耗尽的所有三个Ynd B亚基恢复发芽的孢子人口的水平仅略低于野生型孢子在高发芽浓度。这表明存在不完整的一组Ynd B亚基表现出对发芽的显性负效应，并且Ynd GR的A和C亚基对于Ynd和GerA之间的合作功能是足够的。与Ynd的B亚基不同，GerA的B亚基是氨基酸诱导萌发所必需的。这项研究提供了新的见解的作用，个别GR亚基之间的合作互动GR在触发sporesgermination.IMPORTANCE孢子形成的细菌是食品工业的问题，孢子可以生存去污程序，随后在食品中复活，食品腐败和食源性疾病的风险。当周围环境中存在营养物时，Ynd和GerA萌发受体（GR）协同触发地衣芽孢杆菌孢子的有效萌发。本研究表明，GerA的单个B亚基是Ynd和GerA之间协同功能所必需的，而Ynd GR的三个B亚基是互补的。缺乏单个亚基的GR与其他GR一起刺激萌发的能力可以解释为什么缺乏GR亚基基因的格尔操纵子保持在孢子形成物种的基因组中。
Germination of Bacillus spores is triggered by the binding of specific nutrients to germinant receptors (GRs) located in the spore's inner membrane. The GRs typically consist of A, B, and C subunits, encoded by tricistronic ger operons. The Bacillus licheniformis genome contains the gerA family operons gerA, ynd, and gerK. In contrast to the ABC(D) organization that characterizes gerA operons of many Bacillus species, B. licheniformis genomes contain a pentacistronic ynd operon comprising the yndD, yndE(3), yndE(2), yndF(1), and yndE(1), genes encoding A, B, B, C, and B GR subunits, respectively (subscripts indicate paralogs). Here we show that B. licheniformis spores can germinate in the absence of the Ynd and GerK GRs, although cooperation between all three GRs is required for optimal germination with amino acids. Spores carrying an incomplete set of Ynd B subunits demonstrated reduced germination efficiencies, while depletion of all three Ynd B subunits restored germination of the spore population to levels only slightly lower than those of wild-type spores at high germinant concentrations. This suggests that the presence of an incomplete set of Ynd B subunits exhibits a dominant negative effect on germination and that the A and C subunits of the Ynd GR are sufficient for the cooperative functionality between Ynd and GerA. In contrast to the B subunits of Ynd, the B subunit of GerA was essential for amino acid-induced germination. This study provides novel insights into the role of individual GR subunits in the cooperative interaction between GRs in triggering spore germination.IMPORTANCE Spore-forming bacteria are problematic for the food industry, as spores can survive decontamination procedures and subsequently revive in food products, with the risk of food spoilage and foodborne disease. The Ynd and GerA germination receptors (GRs) cooperate in triggering efficient germination of Bacillus licheniformis spores when nutrients are present in the surrounding environment. This study shows that the single B subunit of GerA is essential for the cooperative function between Ynd and GerA, while the three B subunits of the Ynd GR are dispensable. The ability of GRs lacking individual subunits to stimulate germination together with other GRs could explain why ger operons lacking GR subunit genes are maintained in genomes of spore-forming species.