Acebrón Sergio P, Fernández-Sáiz Vanesa, Taneva Stefka G, Moro Fernando, Muga Arturo
Unidad de Biofísica (Consejo Superior de Investigaciones Científicas/Universidad del País Vasco-Euskal Henriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, P.O. Box 644, Bilbao 48080, Spain.
Unidad de Biofísica (Consejo Superior de Investigaciones Científicas/Universidad del País Vasco-Euskal Henriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, P.O. Box 644, Bilbao 48080, Spain.
J Biol Chem. 2008 Jan 18;283(3):1381-1390. doi: 10.1074/jbc.M706189200. Epub 2007 Nov 5.
Thermal stress might lead to protein aggregation in the cell. Reactivation of protein aggregates depends on Hsp100 and Hsp70 chaperones. We focus in this study on the ability of DnaK, the bacterial representative of the Hsp70 family, to interact with different aggregated model substrates. Our data indicate that DnaK binding to large protein aggregates is mediated by DnaJ, and therefore it depends on its affinity for the cochaperone. Mutations in the structural region of DnaK known as the "latch" decrease the affinity of the chaperone for DnaJ, resulting in a defective activity as protein aggregate-removing agent. As expected, the chaperone activity is recovered when DnaJ concentration is raised to overcome the lower affinity of the mutant for the cochaperone, suggesting that a minimum number of aggregate-bound DnaK molecules is necessary for its efficient reactivation. Our results provide the first experimental evidence of DnaJ-mediated recruiting of ATP-DnaK molecules to the aggregate surface.
热应激可能导致细胞内蛋白质聚集。蛋白质聚集体的重新激活依赖于Hsp100和Hsp70伴侣蛋白。在本研究中，我们聚焦于Hsp70家族的细菌代表DnaK与不同聚集模型底物相互作用的能力。我们的数据表明，DnaK与大的蛋白质聚集体的结合是由DnaJ介导的，因此它取决于其对共伴侣蛋白的亲和力。DnaK结构区域中被称为“闩锁”的突变降低了伴侣蛋白对DnaJ的亲和力，导致其作为蛋白质聚集体去除剂的活性存在缺陷。正如预期的那样，当提高DnaJ浓度以克服突变体对共伴侣蛋白较低的亲和力时，伴侣蛋白活性得以恢复，这表明聚集结合的DnaK分子的最小数量对于其有效重新激活是必要的。我们的结果提供了DnaJ介导的ATP-DnaK分子募集到聚集体表面的首个实验证据。
