Department of Chemistry, University of Southern California, Los Angeles, California, USA.
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
Protein Sci. 2024 Oct;33(10):e5173. doi: 10.1002/pro.5173.
Almost all types of cellular stress induce post-translational O-GlcNAc modifications of proteins, and this increase promotes cell survival. We previously demonstrated that O-GlcNAc on certain small heat shock proteins (sHSPs), including HSP27, directly increases their chaperone activity as one potential protective mechanism. Here, we furthered our use of synthetic proteins to prepare biotinylated sHSPs and show that O-GlcNAc modification of HSP27 also changes how it interacts within the sHSP system and the broader HSP network. Specifically, we show that O-GlcNAc modified HSP27 binds more strongly to the co-chaperone protein BAG3, which then promotes refolding of a model substrate by HSP70. We use proteomics to identify other potential HSP27 interactions that are changed by O-GlcNAc, including one that we confirm with another sHSP, αB-crystallin. These findings add additional evidence for O-GlcNAc as a switch for regulating protein-protein interactions and for modifications of chaperones as one mechanism by which O-GlcNAc protects against protein aggregation.
几乎所有类型的细胞应激都会诱导蛋白质的 O-GlcNAc 后翻译修饰，这种增加促进了细胞存活。我们之前证明，某些小分子热休克蛋白 (sHSP) 上的 O-GlcNAc，包括 HSP27，直接增加了它们的伴侣活性，这是一种潜在的保护机制。在这里，我们进一步利用合成蛋白来制备生物素化的 sHSP，并表明 HSP27 的 O-GlcNAc 修饰还改变了它在 sHSP 系统和更广泛的 HSP 网络中的相互作用方式。具体来说，我们表明 O-GlcNAc 修饰的 HSP27 与共伴侣蛋白 BAG3 结合更牢固，然后促进 HSP70 对模型底物的重折叠。我们使用蛋白质组学来鉴定 O-GlcNAc 改变的其他潜在 HSP27 相互作用，包括我们用另一种 sHSP，αB-晶状体蛋白，证实的一种相互作用。这些发现为 O-GlcNAc 作为调节蛋白质-蛋白质相互作用的开关以及 O-GlcNAc 作为保护蛋白质免受聚集的一种机制来修饰伴侣蛋白提供了更多证据。
