School of Life Sciences, University of Warwick, Coventry, United Kingdom.
J Bacteriol. 2024 Jul 25;206(7):e0022024. doi: 10.1128/jb.00220-24. Epub 2024 Jun 21.
During spore development in bacteria, a polar septum separates two transcriptionally distinct cellular compartments, the mother cell and the forespore. The conserved serine phosphatase SpoIIE is known for its critical role in the formation of this septum and activation of compartment-specific transcription in the forespore. Signaling between the mother cell and forespore then leads to activation of mother cell transcription and a phagocytic-like process called engulfment, which involves dramatic remodeling of the septum and requires a balance between peptidoglycan synthesis and hydrolysis to ensure septal stability and compartmentalization. Using , we identify an additional role for SpoIIE in maintaining septal stability and compartmentalization at the onset of engulfment. This role for SpoIIE is mediated by SpoIIQ, which anchors SpoIIE in the engulfing membrane. A SpoIIQ mutant (SpoIIQ Y28A) that fails to anchor SpoIIE, results in septal instability and miscompartmentalization during septal peptidoglycan hydrolysis, when other septal stabilization factors are absent. Our data support a model whereby SpoIIE and its interactions with the peptidoglycan synthetic machinery contribute to the stabilization of the asymmetric septum early in engulfment, thereby ensuring compartmentalization during spore development.IMPORTANCEBacterial sporulation is a complex process involving a vast array of proteins. Some of these proteins are absolutely critical and regulate key points in the developmental process. Once such protein is SpoIIE, known for its role in the formation of the polar septum, a hallmark of the early stages of sporulation, and activation of the first sporulation-specific sigma factor, σF, in the developing spore. Interestingly, SpoIIE has been shown to interact with SpoIIQ, an important σF-regulated protein that functions during the engulfment stage. However, the significance of this interaction has remained unclear. Here, we unveil the importance of the SpoIIQ-SpoIIE interaction and identify a role for SpoIIE in the stabilization of the polar septum and maintenance of compartmentalization at the onset of engulfment. In this way, we demonstrate that key sporulation proteins, like SpoIIQ and SpoIIE, function in multiple processes during spore development.
在细菌的孢子发育过程中，极性隔膜将两个转录上不同的细胞隔室，母细胞和前孢子隔开。保守的丝氨酸磷酸酶 SpoIIE 以其在隔膜形成和前孢子中特定隔室转录的激活中的关键作用而闻名。然后，母细胞和前孢子之间的信号传导导致母细胞转录的激活和吞噬样过程称为吞噬，这涉及隔膜的剧烈重塑，并且需要肽聚糖合成和水解之间的平衡，以确保隔膜的稳定性和分区。使用 ，我们确定了 SpoIIE 在吞噬作用开始时维持隔膜稳定性和分区的另一个作用。SpoIIE 的这种作用是由 SpoIIQ 介导的，SpoIIQ 将 SpoIIE 锚定在吞噬膜中。无法锚定 SpoIIE 的 SpoIIQ 突变体（SpoIIQ Y28A）在前孢子期肽聚糖水解过程中导致隔膜不稳定和分区错误，而其他隔膜稳定因子不存在时。我们的数据支持这样一种模型，即 SpoIIE 及其与肽聚糖合成机制的相互作用有助于在吞噬作用早期稳定不对称隔膜，从而确保孢子发育过程中的分区。
重要性
细菌孢子形成是一个复杂的过程，涉及大量的蛋白质。其中一些蛋白质是绝对关键的，它们调节发育过程中的关键点。这样的蛋白质之一是 SpoIIE，它以其在极性隔膜形成中的作用而闻名，这是孢子形成早期阶段的标志，也是发育中的孢子中第一个孢子特异性σ因子σF 的激活。有趣的是，已经表明 SpoIIE 与 SpoIIQ 相互作用，SpoIIQ 是一种重要的 σF 调节蛋白，在吞噬阶段起作用。然而，这种相互作用的意义仍然不清楚。在这里，我们揭示了 SpoIIQ-SpoIIE 相互作用的重要性，并确定了 SpoIIE 在极性隔膜的稳定和吞噬作用开始时分区的维持中的作用。通过这种方式，我们证明了关键的孢子形成蛋白，如 SpoIIQ 和 SpoIIE，在孢子发育过程中的多个过程中发挥作用。
