Replication-coupled (RC) nucleosome assembly is an essential process in eukaryotic cells to maintain chromatin structure during DNA replication. The deposition of newly-synthesized H3/H4 histones during DNA replication is facilitated by specialized histone chaperones. CAF-1 is an important histone chaperone complex and its main subunit, Cac1p, contains a PIP and WHD domain for interaction with PCNA and the DNA, respectively. While Cac1p subunit was extensively studied in different systems much less is known regarding the importance of the PIP and WHD domains in replication fork progression and genome stability. By exploiting a time-lapse microscopy system for monitoring DNA replication in individual live cells, we examined how mutations in these Cac1p domains affect replication fork progression and post-replication characteristics. Our experiments revealed that mutations in the Cac1p WHD domain, which abolished the CAF-1–DNA interaction, slows down replication fork progression. In contrast, mutations in Cac1p PIP domain, abolishing Cac1p–PCNA interaction, lead to extended late-S/Anaphase duration, elevated number of RPA foci and increased spontaneous mutation rate. Our research shows that Cac1p WHD and PIP domains have distinct roles in high replisome progression and maintaining genome stability during cell cycle progression.

复制耦合（RC）核小体装配是真核细胞在DNA复制过程中维持染色质结构的重要过程。专门的组蛋白伴侣可以促进DNA复制过程中新合成的H3 / H4组蛋白的沉积。CAF-1是一种重要的组蛋白伴侣复合物，其主要亚基Cac1p包含一个PIP和WHD域，分别与PCNA和DNA相互作用。虽然在不同系统中广泛研究了Cac1p亚基，但对于PIP和WHD域在复制叉进展和基因组稳定性中的重要性知之甚少。通过利用延时显微镜系统监测单个活细胞中的DNA复制，我们检查了这些Cac1p域中的突变如何影响复制叉的进展和复制后的特征。我们的实验表明，Cac1p WHD域中的突变消除了CAF-1-DNA的相互作用，从而减慢了复制叉的发展。相反，Cac1p PIP域中的突变消除了Cac1p-PCNA的相互作用，导致后期S /后期持续时间延长，RPA病灶数量增加和自发突变率增加。我们的研究表明，Cac1p WHD和PIP域在高复制过程中具有独特的作用，并在细胞周期过程中保持基因组稳定性。