X-ray survival characteristics and genetic analysis for nineSaccharomyces deletion mutants that affect radiation sensitivity

Journal Article · Fri Jul 21 04:00:00 EDT 2006 · Genetics

DOI:https://doi.org/10.1534/genetics.106.057794· OSTI ID:920066

Game, John C; Williamson, Marsha S; Baccari, Clelia

We examine ionizing radiation (IR) sensitivity and epistasisrelationships of several Saccharomyces mutants affectingpost-translational modifications of histones H2B and H3. Mutantsbre1delta, lge1delta, and rtf1delta, defective in histone H2B lysine 123ubiquitination, show IR sensitivity equivalent to that of the dot1deltamutant that we reported on earlier, consistent with published findingsthat Dot1p requires H2B K123 ubiquitination to fully methylate histone H3K79. This implicates progressive K79 methylation rather thanmono-methylation in IR resistance. The set2delta mutant, defective in H3K36 methylation, shows mild IR sensitivity whereas mutants that abolishH3 K4 methylation resemble wild type. The dot1delta, bre1delta, andlge1delta mutants show epistasis for IR sensitivity. The paf1deltamutant, also reportedly defective in H2B K123 ubiquitination, confers nosensitivity. The rad6delta, rad51null, rad50delta, and rad9deltamutations are epistatic to bre1? and dot1delta, but rad18delta andrad5delta show additivity with bre1delta, dot1delta, and each other. Thebre1delta rad18delta double mutant resembles rad6delta in sensitivity;thus the role of Rad6p in ubiquitinating H2B accounts for its extrasensitivity compared to rad18delta. We conclude that IR resistanceconferred by BRE1 and DOT1 is mediated through homologous recombinationalrepair, not postreplication repair, and confirm findings of a G1checkpoint role for the RAD6/BRE1/DOT1 pathway.

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE Director, Office of Science; National Institutes ofHealth
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 920066
• Report Number(s): LBNL--60091; BnR: 400412000
• Journal Information: Genetics, Journal Name: Genetics Journal Issue: 4 Vol. 173; ISSN 0016-6731; ISSN GENTAE
• Country of Publication: United States
• Language: English

Related Subjects

57
60 APPLIED LIFE SCIENCES
AMINO ACIDS
DNA REPAIR
GENES
IONIZING RADIATIONS
MUTANTS
PHENOTYPE
RADIATIONS
REPAIR
SACCHAROMYCES
SENSITIVITY
Saccharomyces Histones Radiation