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Molecular and reverse genetic characterization of NUCLEOSOME ASSEMBLY PROTEIN1 ( NAP1 ) genes unravels their function in transcription and nucleotide excision repair in Arabidopsis thaliana
Author(s) -
Liu Ziqiang,
Zhu Yan,
Gao Juan,
Yu Fang,
Dong Aiwu,
Shen WenHui
Publication year - 2009
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2009.03844.x
Subject(s) - biology , nucleotide excision repair , gene , arabidopsis , chromatin , histone , genetics , nucleosome , dna repair , mutant , microbiology and biotechnology , chromatin remodeling
Summary Compared with the well‐studied biochemical function of NUCLEOSOME ASSEMBLY PROTEIN1 (NAP1) as a histone chaperone in nucleosome assembly/disassembly, the physiological roles of NAP1 remain largely uncharacterized. Here, we define the NAP1 gene family members in Arabidopsis, examine their molecular properties, and use reverse genetics to characterize their biological roles. We show that the four AtNAP1‐group proteins can form homodimers and heterodimers, can bind histone H2A, and are localized abundantly in the cytoplasm and weakly in the nucleus at steady state. AtNAP1;4 differs from the others by showing inhibitor‐sensitive nucleocytoplasmic shuttling and tissue‐specific expression, restricted to root segments and pollen grains. The other three AtNAP1 genes are ubiquitously expressed in plants and the AtNAP1;3 protein is detected as the major isoform in seedlings. We show that disruption of the AtNAP1 ‐group genes does not affect normal plant growth under our laboratory conditions. Interestingly, two allelic triple mutants, Atnap1;1‐1 Atnap1;2‐1 Atnap1;3‐1 and Atnap1;1‐1 Atnap1;2‐1 Atnap1;3‐2 , exhibit perturbed genome transcription, and show hypersensitivity to DNA damage caused by UV‐C irradiation. We show that AtNAP1;3 binds chromatin, with enrichment at some genes involved in the nucleotide excision repair (NER) pathway, and that the expression of these genes is downregulated in the triple mutants. Taken together, our results highlight conserved and isoform‐specific properties of AtNAP1 proteins, and unravel their function in the NER pathway of DNA damage repair.