Division of Chemistry and Biological Chemistry (CBC), School of Physical and Mathematical Sciences (SPMS), Nanyang Technological University, 21 Nanyang Link, S637371 Singapore.
ACS Chem Biol. 2022 Sep 16;17(9):2538-2550. doi: 10.1021/acschembio.2c00468. Epub 2022 Aug 15.
, the major fungal pathogen in humans, is under the strong influence of bacterial peptidoglycan fragments to undergo the yeast-to-hyphae transition, a key virulent step in pathogenesis and infections. However, due to the synthetic difficulties of obtaining peptidoglycan fragments for biological studies, mechanistic details of how recognizes and uptakes these peptidoglycan fragments have not been well elucidated. Notably, previous works have solely focused on the synthetic peptidoglycan ligand, muramyl dipeptide (MDP), despite its poor hyphal-inducing activity in . In this work, we isolated and purified natural peptidoglycan fragments via enzymatic degradation of bacteria cell wall sacculi and chemoenzymatically installed a series of functional d-amino acids into the natural muropeptide, creating peptidoglycan probes that bear photoaffinity, bio-orthogonal, or fluorescent functionality. Using these chemoenzymatic peptidoglycan probes, we established that natural peptidoglycan fragments, which are potent hyphal-inducers, interact with the Cyr1 sensor protein in the in-gel fluorescence assay as well as in pulldown studies. Moreover, we established that bacterial peptidoglycan probes enter cells via an energy-dependent endocytic process.
白色念珠菌是人类主要的真菌病原体，它在细菌肽聚糖片段的强烈影响下经历从酵母到菌丝的转变，这是致病和感染过程中的一个关键毒力步骤。然而，由于获得肽聚糖片段进行生物研究的合成困难， 识别和摄取这些肽聚糖片段的机制细节尚未得到很好的阐明。值得注意的是，以前的工作仅专注于合成肽聚糖配体，即 muramyl dipeptide (MDP)，尽管其在白色念珠菌中诱导菌丝形成的活性很差。在这项工作中，我们通过细菌细胞壁囊泡的酶解分离和纯化天然肽聚糖片段，并通过化学酶法将一系列功能化的 D-氨基酸引入天然肽聚糖，从而构建了具有光亲和性、生物正交性或荧光功能的肽聚糖探针。利用这些化学酶肽聚糖探针，我们确定了天然肽聚糖片段作为有效的菌丝诱导剂，与凝胶中的荧光测定以及pulldown 研究中的 Cyr1 传感器蛋白相互作用。此外，我们确定了细菌肽聚糖探针通过能量依赖的内吞作用进入细胞。
