HTA2/YBL003C Summary Help

Standard Name HTA2 1
Systematic Name YBL003C
Alias H2A2 2
Feature Type ORF, Verified
Description Histone H2A; core histone protein required for chromatin assembly and chromosome function; one of two nearly identical (see also HTA1) subtypes; DNA damage-dependent phosphorylation by Mec1p facilitates DNA repair; acetylated by Nat4p (2, 3, 4, 5, 6 and see Summary Paragraph)
Name Description Histone h Two A 2
Chromosomal Location
ChrII:235792 to 235394 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: .2 cM
Gene Ontology Annotations All HTA2 GO evidence and references
  View Computational GO annotations for HTA2
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 9 genes
Classical genetics
Large-scale survey
414 total interaction(s) for 282 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 335
  • Affinity Capture-RNA: 5
  • Affinity Capture-Western: 23
  • Biochemical Activity: 2
  • Co-fractionation: 1
  • Co-purification: 2
  • Far Western: 1
  • PCA: 2
  • Reconstituted Complex: 8

Genetic Interactions
  • Dosage Growth Defect: 2
  • Negative Genetic: 11
  • Phenotypic Suppression: 1
  • Positive Genetic: 8
  • Synthetic Growth Defect: 8
  • Synthetic Lethality: 3
  • Synthetic Rescue: 2

Expression Summary
Length (a.a.) 132
Molecular Weight (Da) 13,989
Isoelectric Point (pI) 11.43
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrII:235792 to 235394 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: .2 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1997-01-28
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..399 235792..235394 2011-02-03 1997-01-28
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000000099

About yeast nucleosomes...

Chromatin is composed of arrays of nucleosomes, with each nucleosome comprising an octamer formed by two copies each of the H2A-H2B and H3-H4 heterodimers (7). In Saccharomyces cerevisiae, each of the canonical histones is encoded by two genes: H2A by HTA1 and HTA2, H2B by HTB1 and HTB2, H3 by HHT1 and HHT2, and H4 by HHF1 and HHF2. The eight genes are organized into four pairs of divergently-transcribed loci: HTA1-HTB1 and HTA2-HTB2, each encoding histone proteins H2A and H2B; and HHT1-HHF1 and HHT2-HHF2, each encoding histone proteins H3 and H4. As a result of this redundancy, deletion of any one histone locus does not cause lethality (8). The H3-H4 protein dimers interact via a four-helix bundle at the H3 C-termini, and the H2A-H2B dimers bind to the resulting central H3-H4 tetramer via a similar four-helix bundle interaction between the H2B and H4 C-termini (9). Approximately 150 bp of duplex DNA is wound onto the histone octamer as two turns of a negative superhelix (10). A single copy of the linker histone H1 (encoded by HHO1) binds between the superhelices at the site of DNA entry and exit. In some nucleosomes, the histone variant H2A.Z (encoded by HTZ1) is substituted for the canonical H2A in a wide, but nonrandom, genomic distribution, enriched in promoter regions as compared to coding regions (11). The positioning of nucleosomes along chromatin has been implicated in the regulation of gene expression, since the packaging of DNA into nucleosomes affects sequence accessibility (12). Nucleosomes prevent many DNA-binding proteins from approaching their sites (13, 14, 15), whereas appropriately positioned nucleosomes can bring discontiguous DNA sequences into close proximity to promote transcription (16).

About histone H2A...

Similar to other histones, H2A has a positively charged N-terminus (residues 1-21) that extends into the extranucleosomal space (17, 18). H2A is unique, however, in that its C-terminus (amino acids 121-132) also extends outside the nucleosome. Both termini contain modifiable residues with roles in different cellular processes, such as telomere position effect (TPE) and double-strand break (DSB) repair (17, 19).

Differential acetylation and deacetylation of lysines 5 and 8 appears to regulate telomeric silencing, and phosphorylation of threonine 126 is also required for proper TPE (17). Phosphorylation of serine 122 is necessary for survival in the presence of DNA damage, and also for sporulation, indicating a possible role in homologous recombination (19). Phosphorylation of serine 129 is crucial for G1 DNA damage checkpoint regulation, chromatin remodeling, and DSB repair through the recruitment of repair components (20, 21, 4, 22). Following DSB damage, Tel1p phosphorylates S129, which is situated within a conserved SQE consensus target motif, over a large domain encompassing many kilobases surrounding the DSB (20, 21, 4). The Rad9p checkpoint protein is recruited to this domain and phosphorylated by Mec1p, which activates the checkpoint kinase Rad53p and induces a G1 delay (20). Binding of the NuA4 nucleosomal histone acetyltransferase complex to phosphorylated H2A results in acetylation of H4, followed by recruitment of the SWR and INO80 chromatin remodeling complexes (23, 24). SWR catalyzes exchange of histone H2A for the variant H2A.Z (Htz1p), while INO80 displaces histone octamers and facilitates resection to form ssDNA at DSBs (25, 26, 27, 28, 29, 30, 31).

Deletion of either the N- or C-terminus of H2A reduces TPE efficiency, and deletion of the N-terminus or lack of T126 phosphorylation reduces non-homologous end joining (17). Mutants lacking phosphorylation at S122 exhibit impaired sporulation (19). Mutants lacking phosphorylation at S129 show defects in the G1 checkpoint response, including attenuated cell cycle delay, decreased Rad53p kinase activation, and reduced Rad9p phosphorylation and recruitment to damaged sites (20).

Last updated: 2007-05-31 Contact SGD

References cited on this page View Complete Literature Guide for HTA2
1) Kolodrubetz D, et al.  (1982) Histone H2A subtypes associate interchangeably in vivo with histone H2B subtypes. Proc Natl Acad Sci U S A 79(24):7814-8
2) Choe J, et al.  (1982) The two yeast histone H2A genes encode similar protein subtypes. Proc Natl Acad Sci U S A 79(5):1484-7
3) Norris D, et al.  (1988) The effect of histone gene deletions on chromatin structure in Saccharomyces cerevisiae. Science 242(4879):759-61
4) Downs JA, et al.  (2000) A role for Saccharomyces cerevisiae histone H2A in DNA repair. Nature 408(6815):1001-4
5) Meeks-Wagner D and Hartwell LH  (1986) Normal stoichiometry of histone dimer sets is necessary for high fidelity of mitotic chromosome transmission. Cell 44(1):43-52
6) Song OK, et al.  (2003) An Nalpha-acetyltransferase responsible for acetylation of the N-terminal residues of histones H4 and H2A. J Biol Chem 278(40):38109-12
7) Schafer G, et al.  (2005) The Saccharomyces cerevisiae linker histone Hho1p, with two globular domains, can simultaneously bind to two four-way junction DNA molecules. Biochemistry 44(50):16766-75
8) Dollard C, et al.  (1994) SPT10 and SPT21 are required for transcription of particular histone genes in Saccharomyces cerevisiae. Mol Cell Biol 14(8):5223-8
9) Luger K, et al.  (1997) Crystal structure of the nucleosome core particle at 2.8 A resolution. Nature 389(6648):251-60
10) Richmond TJ and Davey CA  (2003) The structure of DNA in the nucleosome core. Nature 423(6936):145-50
11) Li B, et al.  (2005) Preferential occupancy of histone variant H2AZ at inactive promoters influences local histone modifications and chromatin remodeling. Proc Natl Acad Sci U S A 102(51):18385-90
12) Yuan GC, et al.  (2005) Genome-scale identification of nucleosome positions in S. cerevisiae. Science 309(5734):626-30
13) Anderson JD and Widom J  (2000) Sequence and position-dependence of the equilibrium accessibility of nucleosomal DNA target sites. J Mol Biol 296(4):979-87
14) Wallrath LL, et al.  (1994) Architectural variations of inducible eukaryotic promoters: preset and remodeling chromatin structures. Bioessays 16(3):165-70
15) Venter U, et al.  (1994) A nucleosome precludes binding of the transcription factor Pho4 in vivo to a critical target site in the PHO5 promoter. EMBO J 13(20):4848-55
16) Stunkel W, et al.  (1997) A nucleosome positioned in the distal promoter region activates transcription of the human U6 gene. Mol Cell Biol 17(8):4397-405
17) Wyatt HR, et al.  (2003) Multiple roles for Saccharomyces cerevisiae histone H2A in telomere position effect, Spt phenotypes and double-strand-break repair. Genetics 164(1):47-64
18) Luger K and Richmond TJ  (1998) The histone tails of the nucleosome. Curr Opin Genet Dev 8(2):140-6
19) Harvey AC, et al.  (2005) Saccharomyces cerevisiae histone H2A Ser122 facilitates DNA repair. Genetics 170(2):543-53
20) Javaheri A, et al.  (2006) Yeast G1 DNA damage checkpoint regulation by H2A phosphorylation is independent of chromatin remodeling. Proc Natl Acad Sci U S A 103(37):13771-6
21) Fink M, et al.  (2007) Contribution of the Serine 129 of Histone H2A to Chromatin Structure. Mol Cell Biol 27(10):3589-600
22) Shim EY, et al.  (2007) RSC mobilizes nucleosomes to improve accessibility of repair machinery to the damaged chromatin. Mol Cell Biol 27(5):1602-13
23) Doyon Y and Cote J  (2004) The highly conserved and multifunctional NuA4 HAT complex. Curr Opin Genet Dev 14(2):147-54
24) Downs JA, et al.  (2004) Binding of chromatin-modifying activities to phosphorylated histone H2A at DNA damage sites. Mol Cell 16(6):979-90
25) Korber P and Horz W  (2004) SWRred not shaken; mixing the histones. Cell 117(1):5-7
26) Krogan NJ, et al.  (2003) The Paf1 complex is required for histone H3 methylation by COMPASS and Dot1p: linking transcriptional elongation to histone methylation. Mol Cell 11(3):721-9
27) Mizuguchi G, et al.  (2004) ATP-driven exchange of histone H2AZ variant catalyzed by SWR1 chromatin remodeling complex. Science 303(5656):343-8
28) van Attikum H, et al.  (2004) Recruitment of the INO80 complex by H2A phosphorylation links ATP-dependent chromatin remodeling with DNA double-strand break repair. Cell 119(6):777-88
29) Morrison AJ, et al.  (2004) INO80 and gamma-H2AX interaction links ATP-dependent chromatin remodeling to DNA damage repair. Cell 119(6):767-75
30) Shen X, et al.  (2003) Involvement of actin-related proteins in ATP-dependent chromatin remodeling. Mol Cell 12(1):147-55
31) Tsukuda T, et al.  (2005) Chromatin remodelling at a DNA double-strand break site in Saccharomyces cerevisiae. Nature 438(7066):379-83