New nuclear partners for nucleosome assembly protein 1: unexpected associations

2010 ◽  
Vol 88 (6) ◽  
pp. 927-936 ◽  
Author(s):  
Corrine Seebart ◽  
Jessica Prenni ◽  
Miroslav Tomschik ◽  
Jordanka Zlatanova

Histone chaperones are important players in chromatin dynamics. They are instrumental in nucleosome assembly and disassembly and in histone variant exchange reactions that occur during DNA transactions. The molecular mechanisms of their action are not well understood and may involve interactions with various protein partners in the context of the nucleus. In an attempt to further elucidate nuclear roles of histone chaperones, we performed a proteomic search for nuclear partners of a particular histone chaperone, nucleosome assembly protein 1 (Nap1). Proteins recognized as Nap1 partners by immuno-affinity capture and Far Western blots were identified by mass spectrometry. The identified partners are known to participate in a number of nuclear processes, including DNA replication, recombination, and repair as well as RNA transcription and splicing. Finding nuclear actin among the Nap1 partners may be of particular significance, in view of actin’s role in transcription, transcription regulation, and RNA splicing. We are proposing a model of how actin–Nap1 interaction may be involved in transcription elongation through chromatin. In addition, awareness of the interactions between Nap1 and Hsp70, another identified partner, may help to understand nucleosome dynamics around sites of single-strand DNA break repair. These studies represent a starting point for further investigation of Nap1 associations in human cells.

2016 ◽  
Vol 36 (8) ◽  
pp. 1287-1296 ◽  
Author(s):  
Xu Chen ◽  
Sheena D'Arcy ◽  
Catherine A. Radebaugh ◽  
Daniel D. Krzizike ◽  
Holli A. Giebler ◽  
...  

Histone chaperones, like nucleosome assembly protein 1 (Nap1), play a critical role in the maintenance of chromatin architecture. Here, we use theGALlocus inSaccharomyces cerevisiaeto investigate the influence of Nap1 on chromatin structure and histone dynamics during distinct transcriptional states. When theGALlocus is not expressed, cells lacking Nap1 show an accumulation of histone H2A-H2B but not histone H3-H4 at this locus. Excess H2A-H2B interacts with the linker DNA between nucleosomes, and the interaction is independent of the inherent DNA-binding affinity of H2A-H2B for these particular sequences as measuredin vitro. When theGALlocus is transcribed, excess H2A-H2B is reversed, and levels of all chromatin-bound histones are depleted in cells lacking Nap1. We developed anin vivosystem to measure histone exchange at theGALlocus and observed considerable variability in the rate of exchange across the locus in wild-type cells. We recapitulate this variability within vitronucleosome reconstitutions, which suggests a contribution of DNA sequence to histone dynamics. We also find that Nap1 is required for transcription-dependent H2A-H2B exchange. Altogether, these results indicate that Nap1 is essential for maintaining proper chromatin composition and modulating the exchange of H2A-H2Bin vivo.


2006 ◽  
Vol 84 (4) ◽  
pp. 549-549 ◽  
Author(s):  
Young-Jun Park ◽  
Karolin Luger

Homologues of nucleosome assembly protein 1 (NAP1) have been identified in all eukaryotes. Although initially identified as histone chaperones and chromatin-assembly factors, additional functions include roles in tissue-specific transcription regulation, apoptosis, histone shuttling, and cell-cycle regulation, and extend beyond those of a simple chaperone and assembly factor. NAP1 family members share a structurally conserved fold, the NAP domain. Here we review current knowledge of the NAP family of proteins within the context of the recently determined crystal structure of the NAP1 family's first representative, NAP1 from yeast.


2014 ◽  
Vol 34 (5) ◽  
Author(s):  
Hongde Liu ◽  
Min Zhu ◽  
Yawen Mu ◽  
Lingjie Liu ◽  
Guanghui Li ◽  
...  

Histone variant Htz1 substitution for H2A plays important roles in diverse DNA transactions. Histone chaperones Chz1 and Nap1 (nucleosome assembly protein 1) are important for the deposition Htz1 into nucleosomes. In literatures, it was suggested that Chz1 is a Htz1–H2B-specific chaperone, and it is relatively unstructured in solution but it becomes structured in complex with the Htz1–H2B histone dimer. Nap1 (nucleosome assembly protein 1) can bind (H3–H4)2 tetramers, H2A–H2B dimers and Htz1–H2B dimers. Nap1 can bind H2A–H2B dimer in the cytoplasm and shuttles the dimer into the nucleus. Moreover, Nap1 functions in nucleosome assembly by competitively interacting with non-nucleosomal histone–DNA. However, the exact roles of these chaperones in assembling Htz1-containing nucleosome remain largely unknown. In this paper, we revealed that Chz1 does not show a physical interaction with chromatin. In contrast, Nap1 binds exactly at the genomic DNA that contains Htz1. Nap1 and Htz1 show a preferential interaction with AG-rich DNA sequences. Deletion of chz1 results in a significantly decreased binding of Htz1 in chromatin, whereas deletion of nap1 dramatically increases the association of Htz1 with chromatin. Furthermore, genome-wide nucleosome-mapping analysis revealed that nucleosome occupancy for Htz1p-bound genes decreases upon deleting htz1 or chz1, suggesting that Htz1 is required for nucleosome structure at the specific genome loci. All together, these results define the distinct roles for histone chaperones Chz1 and Nap1 to regulate Htz1 incorporation into chromatin.


2011 ◽  
Vol 436 (1) ◽  
pp. 101-112 ◽  
Author(s):  
Masanori Noda ◽  
Susumu Uchiyama ◽  
Adam R. McKay ◽  
Akihiro Morimoto ◽  
Shigeki Misawa ◽  
...  

Proteins often exist as ensembles of interconverting states in solution which are often difficult to quantify. In the present manuscript we show that the combination of MS under nondenaturing conditions and AUC-SV (analytical ultracentrifugation sedimentation velocity) unambiguously clarifies a distribution of states and hydrodynamic shapes of assembled oligomers for the NAP-1 (nucleosome assembly protein 1). MS established the number of associated units, which was utilized as input for the numerical analysis of AUC-SV profiles. The AUC-SV analysis revealed that less than 1% of NAP-1 monomer exists at the micromolar concentration range and that the basic assembly unit consists of dimers of yeast or human NAP-1. These dimers interact non-covalently to form even-numbered higher-assembly states, such as tetramers, hexamers, octamers and decamers. MS and AUC-SV consistently showed that the formation of the higher oligomers was suppressed with increasing ionic strength, implicating electrostatic interactions in the formation of higher oligomers. The hydrodynamic shapes of the NAP-1 tetramer estimated from AUC-SV agreed with the previously proposed assembly models built using the known three-dimensional structure of yeast NAP-1. Those of the hexamer and octamer could be represented by new models shown in the present study. Additionally, MS was used to measure the stoichiometry of the interaction between the human NAP-1 dimer and the histone H2A–H2B dimer or H3–H4 tetramer. The present study illustrates a rigorous procedure for the analysis of protein assembly and protein–protein interactions in solution.


2020 ◽  
Vol 117 (48) ◽  
pp. 30391-30399
Author(s):  
Qiang Luo ◽  
Baihui Wang ◽  
Zhen Wu ◽  
Wen Jiang ◽  
Yueyue Wang ◽  
...  

Nucleosome Assembly Protein 1 (NAP1) family proteins are evolutionarily conserved histone chaperones that play important roles in diverse biological processes. In this study, we determined the crystal structure ofArabidopsisNAP1-Related Protein 1 (NRP1) complexed with H2A-H2B and uncovered a previously unknown interaction mechanism in histone chaperoning. Both in vitro binding and in vivo plant rescue assays proved that interaction mediated by the N-terminal α-helix (αN) domain is essential for NRP1 function. In addition, the C-terminal acidic domain (CTAD) of NRP1 binds to H2A-H2B through a conserved mode similar to other histone chaperones. We further extended previous knowledge of the NAP1-conserved earmuff domain by mapping the amino acids of NRP1 involved in association with H2A-H2B. Finally, we showed that H2A-H2B interactions mediated by αN, earmuff, and CTAD domains are all required for the effective chaperone activity of NRP1. Collectively, our results reveal multiple interaction modes of a NAP1 family histone chaperone and shed light on how histone chaperones shield H2A-H2B from nonspecific interaction with DNA.


Gene ◽  
2001 ◽  
Vol 280 (1-2) ◽  
pp. 107-114 ◽  
Author(s):  
Norihito Nishiyama ◽  
Shun Sawatsubashi ◽  
Masaki Ishida ◽  
Kiyoshi Yamauchi

Biochemistry ◽  
2004 ◽  
Vol 43 (32) ◽  
pp. 10592-10599 ◽  
Author(s):  
Steven J. McBryant ◽  
Olve B. Peersen

2017 ◽  
Vol 37 (1) ◽  
pp. 58-69
Author(s):  
Divya Reddy ◽  
Saikat Bhattacharya ◽  
Vinod Jani ◽  
Uddhavesh Sonavane ◽  
Rajendra Joshi ◽  
...  

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