Localized Peptidoglycan Biosynthesis in Chlamydia trachomatis Conforms to the Polarized Division and Cell Size Reduction Developmental Models.
Localized Peptidoglycan Biosynthesis in Chlamydia trachomatis Conforms to the Polarized Division and Cell Size Reduction Developmental Models.
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DOI：
10.3389/fmicb.2021.733850
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发表时间：
2021
影响因子：
5.2
通讯作者：
Liechti GW
中科院分区：
文献类型：
--
作者：
Liechti GW
细菌中的细胞大小调节是两个基本细胞过程的函数：细胞包膜的扩张及其在最终成为分裂平面的空间限定点处的收缩。在大多数细菌物种中，细胞壁的扩张和限制都依赖于肽聚糖（PG），肽聚糖是一种由糖和氨基酸组成的结构聚合物，可赋予细菌膜强度和刚性。致病性衣原体物种的独特之处在于，它们的细胞壁含有很少的 PG，几乎完全局限于微生物复制形式的明显分裂平面。关于 PG 在沙眼衣原体分裂过程中对其大小和形状的影响程度知之甚少，最近的研究表明该过程是通过极化机制启动的。我们进行了一项成像研究，以确定整个生物体发育周期中衣原体 PG 的尺寸、方向和相对密度。我们的分析表明，沙眼衣原体复制过程中的 PG 可能与四种广泛的结构形式相关：极/隔盘、小/厚环、大环和小/薄环。我们发现隔盘和小/厚环中的 PG 密度似乎最高，表明这些结构可能具有较高的 PG 合成与降解比率。我们还发现，随着沙眼衣原体在其发育周期中的进展，PG结构的总体积平均减少，表明衣原体RB的平均细胞体积可能随着时间的推移而减少。当用微生物两种不同 PG 合酶关键成分的抑制剂处理感染沙眼衣原体的细胞时，我们观察到 PG 合成与降解的比率以及含 PG 结构的体积和形状存在巨大差异。总体而言，我们的结果表明，沙眼衣原体 PG 合酶分别在细胞生长和分裂过程中微生物细胞膜的扩张和收缩过程中差异性地调节 PG 环的扩张和收缩。
Cell size regulation in bacteria is a function of two basic cellular processes: the expansion of the cell envelope and its constriction at spatially defined points at what will eventually become the division plane. In most bacterial species, both cell wall expansion and restriction are dependent on peptidoglycan (PG), a structural polymer comprised of sugars and amino acids that imparts strength and rigidity to bacterial membranes. Pathogenic Chlamydia species are unique in that their cell walls contain very little PG, which is restricted almost entirely to the apparent division plane of the microbe’s replicative forms. Very little is known about the degree to which PG affects the size and shape of C. trachomatis during its division process, and recent studies suggest the process is initiated via a polarized mechanism. We conducted an imaging study to ascertain the dimensions, orientation, and relative density of chlamydial PG throughout the organism’s developmental cycle. Our analysis indicates that PG in replicating C. trachomatis can be associated with four, broad structural forms; polar/septal disks, small/thick rings, large rings, and small/thin rings. We found that PG density appeared to be highest in septal disks and small/thick rings, indicating that these structures likely have high PG synthesis to degradation ratios. We also discovered that as C. trachomatis progresses through its developmental cycle PG structures, on average, decrease in total volume, indicating that the average cell volume of chlamydial RBs likely decreases over time. When cells infected with C. trachomatis are treated with inhibitors of critical components of the microbe’s two distinct PG synthases, we observed drastic differences in the ratio of PG synthesis to degradation, as well as the volume and shape of PG-containing structures. Overall, our results suggest that C. trachomatis PG synthases differentially regulate the expansion and contraction of the PG ring during both the expansion and constriction of the microbe’s cell membrane during cell growth and division, respectively.
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影响因子：
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