About NAP1L / Nucleosome Assembly Protein:
Nucleosome assembly protein 1 (NAP-1) is required to form, maintain, and dynamics of eukaryotic chromatin. It transports histones into the nucleus, assembles nucleosomes, and enhances chromatin fluidity, all of which influence gene transcription.
Chromatin assembly and disassembly are dynamic biological processes that increase chromatin fluidity and control the eukaryotic genome's accessibility to DNA replication, transcription, repair, and cell cycle progression. The nucleosome is the basic structural unit of eukaryotic chromatin, consisting of 146 bp of DNA wrapped around a histone octamer composed of two molecules of each of the histones H2A, H2B, H3, and H4.
Nucleosome Assembly Protein Structure
Yeast NAP-1 is a 48-kDa polypeptide that binds H2A-H2B and H3-H4 and facilitates nucleosome formation in vitro. NAP-1 is found in all eukaryotes, from yeast to humans, and has various and unknown activities in vivo, in addition to its well-known role in chromatin assembly. According to structural and functional investigations, the core domain of yeast NAP-1 (residues 74–365) retains a native-like structure and functions normally in nucleosome assembly. In the absence of denaturing chemicals, sedimentation equilibrium experiments demonstrated that yNAP-1 persists in solution as a stable dimer and self-associated oligomers; monomers are never seen.
NAP-1 has a previously unknown fold composed of a lengthy -helix that is primarily important for dimerization and a -sheet that resembles other known histone chaperone proteins. The structure also provides a mechanism for controlling histone import into the nucleus. The findings of this work are an essential step in mapping yNAP-1 interactions with histones and provide important information on the structural relationship between histone chaperones.