Amino Acid Sequence of Oligopeptide Causes Marked Difference in DNA Compaction and Transcription (Biophysical Journal)

Compaction of T4 phage DNA (166 kbp) by short oligopeptide octamers composed of two types of amino acids, four cationic lysine (K) and four polar non-ionic serine (S) having different sequence order was studied by single-molecule fluorescent microscopy. We found that efficient DNA compaction by oligopeptide octamers depends on the geometrical match between phosphate groups of DNA and cationic amines. The amino acid sequence order in octamers dramatically affects the mechanism of DNA compaction which changes from a discrete all-or-nothing coil-globule transition induced by less efficient (K4S4) octamer to a continuous compaction transition induced by (KS)4 octamer with a stronger DNA-binding character.