Oligomers of human histone chaperone NPM1 alter p300/KAT3B folding to induce autoacetylation

Stephanie Kaypee; Smitha Asoka Sahadevan; Deepthi Sudarshan; Sarmistha Halder Sinha; Shilpa Patil; Parijat Senapati; Gopinath S Kodaganur; Azeem Mohiyuddin; Dipak Dasgupta; Tapas K Kundu

doi:10.1016/j.bbagen.2018.05.003

Oligomers of human histone chaperone NPM1 alter p300/KAT3B folding to induce autoacetylation

Biochim Biophys Acta Gen Subj. 2018 Aug;1862(8):1729-1741. doi: 10.1016/j.bbagen.2018.05.003. Epub 2018 May 8.

Affiliations

¹ Transcription and Disease Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, Karnataka, India.
² Department of Otorhinolaryngology Head and Neck, Sri Devaraj Urs Academy of Higher Education and Research, Kolar, Karnataka, India.
³ Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, West Bengal, India.
⁴ Transcription and Disease Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, Karnataka, India. Electronic address: tapas@jncasr.ac.in.

PMID: 29746960
DOI: 10.1016/j.bbagen.2018.05.003

Abstract

Background: p300 (KAT3B) lysine acetyltransferase activity is modulated under different physiological and pathological contexts through the induction of trans-autoacetylation. This phenomenon is mediated by several factors, mechanisms of which are not fully understood.

Methods: Through acetyltransferase assays using full-length, baculovirus-expressed KATs, the specificity of NPM1-mediated enhancement of p300 autoacetylation was tested. Chaperone assays and tryptophan fluorescence studies were performed to evaluate the NPM1-induced protein folding. The NPM1 oligomer-defective mutant characterization was done by glutaraldehyde-crosslinking. The small-molecule inhibitor of NPM1 oligomerization was used to confirm the absolute requirement of multimeric NPM1 in vivo. Immunohistochemistry analysis of oral cancer patient samples was done to uncover the pathophysiological significance of NPM1-induced p300 autoacetylation.

Results: We find that the histone chaperone NPM1 is a specific inducer of p300 autoacetylation. Distinct from its histone chaperone activity, NPM1 is a molecular chaperone of p300. The biophysical experiments suggest that there is a reversible binding between NPM1 and p300 which can modulate p300 acetyltransferase activity. Disruption of NPM1 oligomerization suggests that oligomeric NPM1 is essential for the induction of p300 autoacetylation. Significantly, we observe a concomitant hyper-autoacetylation of p300 with overexpression of NPM1 in oral cancer samples.

Conclusion: NPM1 can specifically modulate p300 acetyltransferase activity through the enhancement of autoacetylation. The molecular chaperone activity and oligomerization of NPM1 play a pivotal role in this phenomenon.

General significance: NPM1 is overexpressed in several solid cancers, the significance of which is unknown. Induction of p300 autoacetylation could be the cause of NPM1-mediated tumorigenicity.

Keywords: Histone hyperacetylation; Oral cancer; Small molecule inhibitor of NPM1 oligomerization; p300 chaperone; trans-Autoacetylation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Acetylation
E1A-Associated p300 Protein / chemistry*
E1A-Associated p300 Protein / metabolism*
Histones / metabolism*
Humans
Nuclear Proteins / chemistry*
Nuclear Proteins / metabolism*
Nucleophosmin
Protein Binding
Protein Conformation
Protein Folding*
Protein Multimerization*
Tongue Neoplasms / metabolism*
Tongue Neoplasms / pathology
Tumor Cells, Cultured

Substances

Histones
NPM1 protein, human
Nuclear Proteins
Nucleophosmin
E1A-Associated p300 Protein
EP300 protein, human