A comprehensive library of histone mutants identifies nucleosomal residues required for H3K4 methylation.

A comprehensive library encompassing alanine scanning mutations across yeast histones is presented as a Resource that will facilitate screening of chromatin processes. The utility of the library is indicated by screening in cis and in trans for residues that affect histone H3K4 trimethylation, a modification that is associated with actively transcribed genes and known to be mediated by the Set1-COMPASS complex.