Tau auto-acetylation promotes tau-K18 and full-length tau fragmentation.

<p><b>A)</b> Recombinant full length tau (0N4R) or tau-K18 containing only the MTBR repeats were incubated in the presence of CoA or acetyl-CoA for 1 day and reaction products were analyzed by analyzed by SDS-PAGE and Coomassie staining. The fold increase in acetyl-CoA-induced tau-K18 fragments is quantified in <b>(B)</b> and the percent remaining full-length 0N4R-tau is quantified in <b>(C)</b>, which resulted from N = 3 independent experimental replicates. Double asterisks (**) represent p-value ≤ 0.05 using student t-test. <b>D)</b> A time-course analysis of tau-K18 fragmentation was performed in the presence of CoA or acetyl-CoA at the indicated time-points from 0–7 days and tau fragment formation was quantified in <b>(E)</b>. <b>F)</b> Size-exclusion chromatography (SEC) was used to measure tau fragments generated in the absence of cofactor, or in the presence of CoA or acetyl-CoA. Full-length 0N4R tau protein eluted ~ 7.70 min while lower molecular weight tau fragments were detected as slower eluting protein peaks at ~8.60 and ~10.18 min, which are highlighted by the black arrows. <b>G)</b> A sequential tau deletion library containing 10-residue deletions spanning the 126 amino acid tau-K18 fragment (tau-K18Δ1- tau-K18Δ13), or tau cysteine mutants lacking one (C291A or C322A) or both (C291/322A) cysteines were incubated in the presence of CoA or acetyl-CoA for 1 day and analyzed by SDS-PAGE and Coomassie staining. We note that purified tau-K18Δ5 was unstable and therefore was not included in this analysis.