Department of Biochemistry and Molecular Medicine, The George Washington University Medical Center, Washington, DC, USA.
PLoS One. 2013 Aug 1;8(8):e71495. doi: 10.1371/journal.pone.0071495. Print 2013.
P21-activated kinase 1 (PAK1) is activated by binding to GTP-bound Rho GTPases Cdc42 and Rac via its CRIB domain. Here, we provide evidence that S79 in the CRIB domain of PAK1 is not directly involved in this binding but is crucial for PAK1 activation. S79A mutation reduces the binding affinity of PAK1 for the GTPases and inhibits autophosphorylation and kinase activity of PAK1. Thus, this mutation abrogates the ability of PAK1 to induce changes in cell morphology and motility and to promote malignant transformation of prostate epithelial cells. We also show that growth of the prostate cancer cell line PC3 is inhibited by the treatment of a PAK1-inhibiting peptide comprising 19 amino acids centered on S79, but not by the PAK1 peptide containing the S79A mutation, and that this growth inhibition is correlated with reduced autophosphorylation activity of PAK1. Together, these findings demonstrate a significant role of S79 in PAK1 activation and provide evidence for a novel mechanism of the CRIB-mediated interaction of PAK1 with Cdc42 and Rac.
P21 激活激酶 1（PAK1）通过其 CRIB 结构域与 GDP 结合的 Rho GTP 酶 Cdc42 和 Rac 结合而被激活。在这里，我们提供的证据表明 PAK1 的 CRIB 结构域中的 S79 不直接参与这种结合，但对于 PAK1 的激活至关重要。S79A 突变降低了 PAK1 与 GTP 酶的结合亲和力，并抑制了 PAK1 的自磷酸化和激酶活性。因此，这种突变削弱了 PAK1 诱导细胞形态和运动变化以及促进前列腺上皮细胞恶性转化的能力。我们还表明，以 S79 为中心的包含 19 个氨基酸的 PAK1 抑制肽的处理抑制了前列腺癌细胞系 PC3 的生长，但包含 S79A 突变的 PAK1 肽则没有，并且这种生长抑制与 PAK1 的自磷酸化活性降低相关。总之，这些发现表明 S79 在 PAK1 激活中具有重要作用，并为 PAK1 与 Cdc42 和 Rac 的 CRIB 介导相互作用的新机制提供了证据。
