Streamlined high-throughput cloning protocol to generate arrayed mutant libraries.

Large-scale, site-directed mutagenesis enables rapid characterization of the biochemical and biological properties of proteins. Here, we present a cost-effective and adaptable cloning pipeline to generate arrayed gene libraries for a construct of interest. We detail steps to use an open access web app to automate the design of mutagenesis primers optimized for our cloning protocols in a 96-well plate format. The protocol allows most molecular biology labs to clone 96 mutants (from PCR to sequence ready plasmid) in 3 days.

Disease-Associated Mutations in Tau Encode for Changes in Aggregate Structure Conformation.

The accumulation of tau fibrils is associated with neurodegenerative diseases, which are collectively termed tauopathies. Cryo-EM studies have shown that the packed fibril core of tau adopts distinct structures in different tauopathies, such as Alzheimer's disease, corticobasal degeneration, and progressive supranuclear palsy. A subset of tauopathies are linked to missense mutations in the tau protein, but it is not clear whether these mutations impact the structure of tau fibrils. To answer this question, we developed a high-throughput protein purification platform and purified a panel of 37 tau variants using the full-length 0N4R splice isoform. Each of these variants was used to create fibrils in vitro, and their relative structures were studied using a high-throughput protease sensitivity platform. We find that a subset of the disease-associated mutations form fibrils that resemble wild-type tau, while others are strikingly different. The impact of mutations on tau structure was not clearly associated with either the location of the mutation or the relative kinetics of fibril assembly, suggesting that tau mutations alter the packed core structures through a complex molecular mechanism. Together, these studies show that single-point mutations can impact the assembly of tau into fibrils, providing insight into its association with pathology and disease.