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Ancestral sequence reconstruction is a technique that is gaining widespread use in molecular evolution studies and protein engineering. Accurate reconstruction requires the ability to handle appropriately large numbers of sequences, as well as insertion and deletion (indel) events, but available approaches exhibit limitations. To address these limitations, we developed Graphical Representation of Ancestral Sequence Predictions (GRASP), which efficiently implements maximum likelihood methods to enable the inference of ancestors of families with more than 10,000 members. GRASP implements partial order graphs (POGs) to represent and infer insertion and deletion events across ancestors, enabling the identification of building blocks for protein engineering. To validate the capacity to engineer novel proteins from realistic data, we predicted ancestor sequences across three distinct enzyme families: glucose-methanol-choline (GMC) oxidoreductases, cytochromes P450, and dihydroxy/sugar acid dehydratases (DHAD). All tested ancestors demonstrated enzymatic activity. Our study demonstrates the ability of GRASP (1) to support large data sets over 10,000 sequences and (2) to employ insertions and deletions to identify building blocks for engineering biologically active ancestors, by exploring variation over evolutionary time.

Abstract Objective Nuclear Factor One X (NFIX) is a transcription factor expressed by neural stem cells within the developing mouse brain and spinal cord. In order to characterise the pathways by which NFIX may regulate neural stem cell biology within the developing mouse spinal cord, we performed an microarray-based transcriptomic analysis of the spinal cord of embryonic day (E)14.5 Nfix −/− mice in comparison to wild-type controls. Data description Using microarray and differential gene expression analyses, we were able to identify differentially expressed genes in the spinal cords of E14.5 Nfix −/− mice compared to wild-type controls. We performed microarray-based sequencing on spinal cords from n = 3 E14.5 Nfix −/− mice and n = 3 E14.5 Nfix +/+ mice. Differential gene expression analysis, using a false discovery rate (FDR) p-value of p ± 1.5, revealed 1351 differentially regulated genes in the spinal cord of Nfix −/− mice. Of these, 828 were upregulated, and 523 were downregulated. This resource provides a tool to interrogate the role of this transcription factor in spinal cord development.