RT Journal Article SR Electronic T1 Nucleosome positioning on large tandem DNA repeats of the ‘601’ sequence engineered in Saccharomyces cerevisiae JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.08.25.457076 DO 10.1101/2021.08.25.457076 A1 Astrid Lancrey A1 Alexandra Joubert A1 Evelyne Duvernois-Berthet A1 Etienne Routhier A1 Saurabh Raj A1 Agnès Thierry A1 Marta Sigarteu A1 Loic Ponger A1 Vincent Croquette A1 Julien Mozziconacci A1 Jean-Baptiste Boulé YR 2021 UL http://biorxiv.org/content/early/2021/08/25/2021.08.25.457076.abstract AB The so-called 601 DNA sequence is often used to constrain the position of nucleosomes on a DNA molecule in vitro. Although the ability of the 147 base pair sequence to precisely position a nucleosome in vitro is well documented, in vivo application of this property has been explored only in a few studies and yielded contradictory conclusions. Our goal in the present study was to test the ability of the 601 sequence to dictate nucleosome positioning in Saccharomyces cerevisiae in the context of a long tandem repeat array inserted in a yeast chromosome. We engineered such arrays with three different repeat size, namely 167, 197 and 237 base pairs. Although our arrays are able to position nucleosomes in vitro as expected, analysis of nucleosome occupancy on these arrays in vivo revealed that nucleosomes are not preferentially positioned as expected on the 601-core sequence along the repeats and that the measured nucleosome repeat length does not correspond to the one expected by design. Altogether our results demonstrate that the rules defining nucleosome positions on this DNA sequence in vitro are not valid in vivo, at least in this chromosomal context, questioning the relevance of using the 601 sequence in vivo to achieve precise nucleosome positioning on designer synthetic DNA sequences.Competing Interest StatementV.C. is cofounder of PicoTwist.