Co-occupancy of the centromeric DNA by histone H3 and Cse4.

<p>A) Only the 214 bp BglII CEN4 fragment and no full-length minichromosome is detected in the ChIP/qPCR assay. DNA isolated from untreated and BglII-treated lysates was size-fractionated on 2% agarose gel and analyzed by qPCR. A PCR product after 30 cycles of amplification in a conventional PCR reaction with the same primers that were used for qPCR is shown below. B) Minichromosomal CEN DNA can be co-immunoprecipitated with H3 and Cse4. BglII-treated chromatin of the strains 1021 (wt), 1407 (H3-HA3), and 1498 (Cse4-HA6) carrying the minichromosome was either not cross-linked or cross-linked with formaldehyde and immunoprecipitated with anti-HA antibody. The immunoprecipitated DNA was purified and size fractionated and subjected to qPCR analysis. C) CEN DNA of the native chromosome IV can be co-immunoprecipitatd with H3 and Cse4. BglII-treated chromatin of the strains 2059 (wt), 2042 (H3-HA3), and 2043 (Cse4-HA6) with CEN DNA of the native chromosome IV flanked with BglII was either not cross-linked or cross-linked with formaldehyde followed by immunoprecipitation as in (B). D) Flowchart of the sequential Cse4-H3 ChIP. E) Sequential ChIP of minichromosomal CEN DNA. BglII-treated chromatin of the strains 1923 (Cse4-Myc6) and 2300 (H3-HA3, Cse4-Myc6) carrying the minichromosome was cross-linked with formaldehyde and immunoprecipitated with anti-Myc or anti-HA antibody as indicated in the figure, the DNA was eluted off the beads and re-immunoprecipitated with anti-HA antibody. The immunoprecipitated DNA was purified, size fractionated on a 2% agarose gel and subjected to qPCR analysis. F) The same as in (E) but performed with the native CEN DNA. The strains, 2562 (Cse4-Myc6), and 2561 (H3-HA3, Cse4-Myc6) had CEN DNA of the native chromosome IV flanked with BglII. The bar graphs represent the average values from several independent experiments with SDs.