Question

how do histones acquire positive charge in nucleosome?

Answer 1

Histones contain high amounts of two positively charged amino acids: lysine and arginine, and hence they are positively charged.

More to know:

Basic structure of chromatin is composed of DNA wrapped around histones. DNA is negatively charged due to the negatively charged phosphates in the backbone. When positively charged histones bind to DNA, all its negative charge would be counter balanced.