Paukovich, N. | bioRxiv Science

bioRxiv2026

Mitotic kinase regulation of DNA replication forks

While DNA replication forks initiate in S phase, they do not necessarily complete and terminate prior to cell entry into mitosis. How mitotic proteins regulate leftover replication forks is not well-understood. Using reconstituted DNA replication forks with purified proteins, we show that the budding yeast mitotic kinases Clb2-CDK (M-CDK) and Cdc5 (Plk1 homolog) phosphorylate and regulate several replication elongation proteins. Mrc1 phosphorylation by both kinases results in slower replication, and Pol phosphorylation by M-CDK results in less lagging strand initiation. We further show that a phospho-resistant mutant of Pol bypasses M-CDK inhibition of Pol activity in reconstituted replication reactions. Yeast cells expressing the phospho-resistant mutant exhibit faster cell cycle progression revealing a potential negative feedback mechanism between DNA replication forks and mitotic progression.

molecular biology↗

bioRxiv2024

Olduvai domain expression downregulates mitochondrial pathways: implications for human brain evolution and neoteny

Olduvai (formerly DUF1220) protein domains, encoded by the NBPF gene family, have undergone the greatest human lineage-specific copy-number expansion of any coding sequence in the genome and strongly correlate with brain size and neuron number across primates. Here we show that Olduvai domains act in a dosage-dependent manner to suppress mitochondrial metabolism. Transcriptomic, proteomic, and live-cell imaging analyses of cells overexpressing NBPF1 (which encodes seven Olduvai domains) reveal pronounced downregulation of mitochondrial pathways, including electron transport chain components and NADH dehydrogenase activity, as well as reduced mitochondrial abundance. By limiting energy availability, this suppression delays cellular maturation and developmental timing. We propose that the resulting prolongation of neurogenesis increases neuron production, providing a mechanistic link between Olduvai copy number expansion and the evolutionary enlargement of the human brain. This dosage-sensitive mitochondrial regulation may also contribute to broader neotenic features of human development, offering a unifying molecular mechanism for brain expansion and the neotenic traits that distinguish humans from other primates.

genomics↗