Staphylococcus aureus cell wall structure and dynamics during host-pathogen interaction.
Staphylococcus aureus cell wall structure and dynamics during host-pathogen interaction.
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宿主-病原体相互作用过程中金黄色葡萄球菌细胞壁的结构和动力学。
DOI：
10.1371/journal.ppat.1009468
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发表时间：
2021-03
期刊：
影响因子：
6.7
通讯作者：
Foster SJ
中科院分区：
文献类型：
--
作者：
Sutton JAF;Carnell OT;Lafage L;Gray J;Biboy J;Gibson JF;Pollitt EJG;Tazoll SC;Turnbull W;Hajdamowicz NH;Salamaga B;Pidwill GR;Condliffe AM;Renshaw SA;Vollmer W;Foster SJ
肽聚糖是金黄色葡萄球菌细胞壁的主要结构组分，在其中它维持细胞完整性，是与宿主的界面，并且它的合成被开发的一些最关键的抗生素靶向。尽管这一重要性，以及来自体外研究的丰富数据，我们不了解感染过程中肽聚糖的结构和动力学。在这项研究中，我们已经开发了从活动性感染中收获细菌的方法，以纯化细胞壁用于离体生化分析。离体分离的细菌细胞比那些在体外活跃生长的细胞小，具有增厚的细胞壁和减少的肽聚糖交联，类似于静止期细胞。这些特征表明特定肽聚糖稳态机制在疾病中的作用。作为S.金黄色葡萄球菌缺失的青霉素结合蛋白4（PBP4）在体外具有减少的肽聚糖交联，其在感染期间的作用被确立。PBP4的丢失导致S的回收率增加。金黄色葡萄球菌从感染小鼠的肝脏，这与增强的适应性在小鼠和人类巨噬细胞。较厚的细胞壁与肽聚糖水解酶活性降低相关。S.金黄色葡萄球菌具有4种推定的氨基葡萄糖苷酶家族，它们共同对生长至关重要。主要酶SagB的丧失导致鼠感染期间的减毒和人巨噬细胞中存活率的降低。然而，其他三种酶Atl，佐贺和ScaH的损失导致在斑马鱼胚胎，但不是一个鼠，感染模型的集群依赖性衰减。pbp4和sagB缺陷的组合导致亲本毒力的恢复。我们的研究结果表明，在发病过程中适当的细胞壁结构和动力学的重要性，提供了新的见解疾病的机制。耐甲氧西林金黄色葡萄球菌（MRSA）在两家医院和更广泛的社区中的流行给医疗保健提供者带来了巨大的压力。因此，为了发现新的控制机制，重要的是要了解病原体在宿主的相关环境中的行为。这通常受到获得足够的离体病原体样品用于研究的能力的阻碍。我们已经建立了一种分离S.金黄色葡萄球菌从感染的宿主，能够分析细胞形态和结构。S.从感染的肾脓肿中分离的金黄色葡萄球菌比体外指数生长的细胞尺寸更小，细胞壁更厚。它们的细胞壁肽聚糖也较少交联。这些特征表明，控制细胞壁内稳态的成分对感染很重要。我们测试了PBP4的作用，已知PBP4增加细胞壁交联，并发现PBP4突变体在巨噬细胞中的存活率增加，并在鼠宿主中具有适应性。相反，肽聚糖水解酶SagB，其损失导致细胞壁变薄，在小鼠全身性感染模型中减弱，伴随着巨噬细胞内适应性的损失。我们的研究揭示了一个重要的适应宿主环境和参与细胞壁体内稳态的那些组件的作用。
Peptidoglycan is the major structural component of the Staphylococcus aureus cell wall, in which it maintains cellular integrity, is the interface with the host, and its synthesis is targeted by some of the most crucial antibiotics developed. Despite this importance, and the wealth of data from in vitro studies, we do not understand the structure and dynamics of peptidoglycan during infection. In this study we have developed methods to harvest bacteria from an active infection in order to purify cell walls for biochemical analysis ex vivo. Isolated ex vivo bacterial cells are smaller than those actively growing in vitro, with thickened cell walls and reduced peptidoglycan crosslinking, similar to that of stationary phase cells. These features suggested a role for specific peptidoglycan homeostatic mechanisms in disease. As S. aureus missing penicillin binding protein 4 (PBP4) has reduced peptidoglycan crosslinking in vitro its role during infection was established. Loss of PBP4 resulted in an increased recovery of S. aureus from the livers of infected mice, which coincided with enhanced fitness within murine and human macrophages. Thicker cell walls correlate with reduced activity of peptidoglycan hydrolases. S. aureus has a family of 4 putative glucosaminidases, that are collectively crucial for growth. Loss of the major enzyme SagB, led to attenuation during murine infection and reduced survival in human macrophages. However, loss of the other three enzymes Atl, SagA and ScaH resulted in clustering dependent attenuation, in a zebrafish embryo, but not a murine, model of infection. A combination of pbp4 and sagB deficiencies resulted in a restoration of parental virulence. Our results, demonstrate the importance of appropriate cell wall structure and dynamics during pathogenesis, providing new insight to the mechanisms of disease. The prevalence of methicillin resistant Staphylococcus aureus (MRSA) in both hospitals and the wider community places a huge weight on healthcare providers. To discover new control regimes, it is therefore important to understand how the pathogen behaves within the relevant environment of the host. This is often hampered by the ability to obtain sufficient ex vivo pathogen samples for study. We have developed a method to isolate S. aureus from the infected host to be able to analyse cellular morphology and structure. S. aureus, isolated from an infected kidney abscess are smaller in size, with thicker cell walls than exponentially growing cells in vitro. Their cell wall peptidoglycan also is less crosslinked. These features suggested the role of components controlling cell wall homeostasis as being important for infections. We tested the role of PBP4, known to increase cell wall crosslinking and found a pbp4 mutant to have increased survival in macrophages and fitness within the murine host. Conversely the peptidoglycan hydrolase SagB, whose loss results in thinner cell walls was attenuated in the murine systemic model of infection, with concomitant loss of fitness within macrophages. Our study reveals an important adaptation to the host environment and the role of those components involved in cell wall homeostasis in vivo.
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