Fauvet Bruno, Finka Andrija, Castanié-Cornet Marie-Pierre, Cirinesi Anne-Marie, Genevaux Pierre, Quadroni Manfredo, Goloubinoff Pierre
Department of Plant Molecular Biology (DBMV), University of Lausanne, Lausanne, Switzerland.
Department of Ecology, Agronomy and Aquaculture, University of Zadar, Zadar, Croatia.
Front Mol Biosci. 2021 Apr 15;8:653073. doi: 10.3389/fmolb.2021.653073. eCollection 2021.
In eukaryotes, the 90-kDa heat shock proteins (Hsp90s) are profusely studied chaperones that, together with 70-kDa heat shock proteins (Hsp70s), control protein homeostasis. In bacteria, however, the function of Hsp90 (HtpG) and its collaboration with Hsp70 (DnaK) remains poorly characterized. To uncover physiological processes that depend on HtpG and DnaK, we performed comparative quantitative proteomic analyses of insoluble and total protein fractions from unstressed wild-type (WT) and from knockout mutants Δ (ΔKJ), Δ (ΔG), and ΔΔ (ΔKJG). Whereas the ΔG mutant showed no detectable proteomic differences with wild-type, ΔKJ expressed more chaperones, proteases and ribosomes and expressed dramatically less metabolic and respiratory enzymes. Unexpectedly, we found that the triple mutant ΔKJG showed higher levels of metabolic and respiratory enzymes than ΔKJ, suggesting that bacterial Hsp90 mediates the degradation of aggregation-prone Hsp70-Hsp40 substrates. Further experiments suggest that such Hsp90-mediated degradation possibly occurs through the HslUV protease.
在真核生物中，90 kDa热休克蛋白（Hsp90s）是被广泛研究的伴侣蛋白，它们与70 kDa热休克蛋白（Hsp70s）共同控制蛋白质稳态。然而，在细菌中，Hsp90（HtpG）的功能及其与Hsp70（DnaK）的协作仍未得到充分表征。为了揭示依赖于HtpG和DnaK的生理过程，我们对未受胁迫的野生型（WT）以及敲除突变体Δ（ΔKJ）、Δ（ΔG）和ΔΔ（ΔKJG）的不溶性和总蛋白组分进行了比较定量蛋白质组学分析。虽然ΔG突变体与野生型相比未显示出可检测到的蛋白质组差异，但ΔKJ表达了更多的伴侣蛋白、蛋白酶和核糖体，而代谢和呼吸酶的表达则显著减少。出乎意料的是，我们发现三重突变体ΔKJG的代谢和呼吸酶水平高于ΔKJ，这表明细菌Hsp90介导了易于聚集的Hsp70 - Hsp40底物的降解。进一步的实验表明，这种Hsp90介导的降解可能通过HslUV蛋白酶发生。
