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The NuA4 complex promotes Translesion Synthesis (TLS) - mediated DNA damage tolerance

ABSTRACT: DNA lesions can block a replication fork, leading to its collapse and gross chromosomal rearrangements. To circumvent such outcomes, DNA damage tolerance (DDT) pathways become engaged, allowing the replisome to bypass the lesion and complete S phase in the presence of unrepaired damage. Here we demonstrate a newly identified role for NuA4, including complex components Esa1 and Yng2, on the Translesion Synthesis (TLS) branch of DDT. Moreover, Our data suggest that NuA4 functionality within the tolerance pathway is likely direct as genome-wide transcriptional analysis with esa1-L254P mutants showed little changes in the expression of TLS factors compared to wild type during MMS treatment. When Yng2 expression is restricted to G2/M, cell viability and mutagenesis rates are restored to the levels measured when only the error-free branch of DDT is disrupted, indicating that the critical role of NuA4 in TLS functions in G2, after chromosomal replication is complete. Lastly, disruption of HTZ1, the Saccharomyces cerevisiae histone variant H2A.Z and target of NuA4, exhibits mutagenic rates of reversion that are comparable to the levels measured with NuA4 complex mutants, esa1-L254P and yng2Δ.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE66176 | GEO | 2015/02/21

SECONDARY ACCESSION(S): PRJNA276018

REPOSITORIES: GEO

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Project description:ESA1 (essential SAS-family acetyltransferase) is the only known yeast histone acetyltransferase (HAT) required for cell viability. It is a member of the MYST (MOZ, YBF2/SAS3, SAS2, Tip60) family of HAT proteins and contains a conserved acetyltransferase domain in addition to a chromodomain. While ESA1âs HAT activity is important in processes such as deoxyribonucleic acid (DNA) repair, acetylation is likely not its essential function. Our lab has shown that mutants with a single point mutation in the active site cysteine are still viable even though their acetyltransferase abilities are abolished. Furthermore, chromatin immunoprecipitation assays have shown ESA1 distributed evenly along the length of chromatin, not localized to specific promoters as would be expected from a HAT protein involved in transcriptional regulation. As is the case for other HAT proteins, ESA1âs acetyltransferase activity is significant, but in processes such as DNA replication, DNA repair and cell cycle progression. The aim of this project is to determine the essential function of ESA1 - the catalytic subunit of the yeast HAT complex, NuA4 (nucleosome acetyltransferase of H4) â using a bypass suppression screen to identify suppressors of ESA1. It is proposed that suppressing mutations will alter a gene involved in the process that is the essential function of ESA1. Thus, identifying a suppressor that can bypass the need for ESA1 may provide insight into its essential function. Since ESA1 is an essential gene, a haploid esa1â strain in which wild-type ESA1 is provided on a centromeric plasmid was utilized. The bypass suppression screen resulted in suppressors of ESA1 that allowed esa1â cells to be viable even in the absence of the essential gene. These second site suppressors (sup-) of ESA1 each show the Mendelian segregation pattern of the suppressing gene and ESA1 in 2:2 ratios, implying they are single genes unlinked to ESA1. Microarray and nuclear morphology studies show abnormal gene expression and morphology of the esa1ï sup- cells, further implicating the suppressing mutation in DNA repair and replication processes. Investigating ESA1âs essential role and a probable conservation of function across species can provide a deeper understanding of the capabilities of HAT complexes. Experiment Overall Design: Eight samples were analyzed. The only variables are the ESA1 and SUP2 genes. WT (ESA1 SUP2), 2 replicates. Single mutant (ESA1 sup2-), 3 replicates. Double mutant (esa1 sup2-), 3 replicates.

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The NuA4 complex promotes Translesion Synthesis (TLS) - mediated DNA damage tolerance

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