College of Biological and Environmental Engineering, Xi'an University, No. 168 South Taibai Road, Xi'an, 710065, China.
College of Biological and Environmental Engineering, Xi'an University, No. 168 South Taibai Road, Xi'an, 710065, China.
Microbiol Res. 2021 Feb;243:126655. doi: 10.1016/j.micres.2020.126655. Epub 2020 Nov 23.
How cell morphology is maintained in thermophilic bacteria is unknown. In this study, the functions and mechanisms of the potential cell shape determinants (e.g. MreB, MreC, MreD and RodA homologues) of the model extremely thermophilic bacterium Thermus thermophilus were initially analyzed. Deletion of mreC, mreD or rodA only resulted in heterozygous mutants indicating that these genes are all essential. In the MreB-inhibited (by A22) strain and the heterozygous mreC, mreD or rodA mutant, cell morphologies were drastically changed, and enlarged spherical cells were eventually dead indicating that they are vital for cell shape maintenance. When fused to sGFP, MreB, MreC, MreD, RodA, and the enzymes involved in peptidoglycan synthesis (e.g. PBP2 and MurG) exhibited similar subcellular localization pattern, appearing as patches, or bands slightly angled to the cell length. The localizations and functions of all the 6 proteins required a natural peptidoglycan synthesis pattern, additionally those of MreD, RodA and MurG were dependent on MreB polymerization. Consistently, through comprehensive bacterial two-hybrid analyses, it was revealed that MreB could interact with itself, MreC, MreD, RodA and MurG, and MreC could associate with PBP2. In conclusion, in T. thermophilus, MreB, MreC, MreD, RodA and the peptidoglycan synthesis enzymes probably form a network of interactions centered with MreB and bridged with MreC, thereby maintaining cell morphology.
嗜热菌如何维持细胞形态尚不清楚。本研究初步分析了模式极端嗜热菌 Thermus thermophilus 中潜在的细胞形状决定因素（如 MreB、MreC、MreD 和 RodA 同源物）的功能和机制。mreC、mreD 或 rodA 的缺失仅导致杂合突变体，表明这些基因都是必需的。在 MreB 抑制（由 A22 抑制）菌株和杂合 mreC、mreD 或 rodA 突变体中，细胞形态发生了剧烈变化，最终增大的球形细胞死亡，表明它们对维持细胞形状至关重要。当与 sGFP 融合时，MreB、MreC、MreD、RodA 和参与肽聚糖合成的酶（如 PBP2 和 MurG）表现出相似的亚细胞定位模式，呈斑点状或与细胞长度成轻微角度的条带。这 6 种蛋白质的定位和功能都需要一种天然的肽聚糖合成模式，此外，MreD、RodA 和 MurG 的定位和功能都依赖于 MreB 的聚合。一致地，通过全面的细菌双杂交分析，揭示了 MreB 可以与自身、MreC、MreD、RodA 和 MurG 相互作用，而 MreC 可以与 PBP2 结合。总之，在 T. thermophilus 中，MreB、MreC、MreD、RodA 和肽聚糖合成酶可能形成以 MreB 为中心并通过 MreC 桥接的相互作用网络，从而维持细胞形态。
