title: Identification of RNR4, encoding a second essential small subunit of ribonucleotide reductase in Saccharomyces cerevisiae.
abstract: Ribonucleotide reductase (RNR), which catalyzes the rate-limiting step for deoxyribonucleotide production required for DNA synthesis, is an alpha2beta2 tetramer consisting of two large and two small subunits. RNR2 encodes a small subunit and is essential for mitotic viability in Saccharomyces cerevisiae. We have cloned a second essential gene encoding a homologous small subunit, RNR4. RNR4 and RNR2 appear to have nonoverlapping functions and cannot substitute for each other even when overproduced. The lethality of RNR4 deletion mutations can be suppressed by overexpression of RNR1 and RNR3, two genes encoding the large subunit of the RNR enzyme, indicating genetic interactions among the RNR genes. RNR2 and RNR4 may be present in the same reductase complex in vivo, since they coimmunoprecipitate from cell extracts. Like the other RNR genes, RNR4 is inducible by DNA-damaging agents through the same signal transduction pathway involving MEC1, RAD53, and DUN1 kinase genes. Analysis of DNA damage inducibility of RNR2 and RNR4 revealed partial inducibility in dun1 mutants, indicating a DUN1-independent branch of the transcriptional response to DNA damage.
authors.affiliation: Verna and Mars McLean Department of Biochemistry, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: M
authors.initials: M
authors.lastname: Huang
authors.forename: S J
authors.initials: SJ
authors.lastname: Elledge
mesh_terms: D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins; D064447:Checkpoint Kinase 2; D003001:Cloning, Molecular; D004249:DNA Damage; D004261:DNA Replication; D004271:DNA, Fungal; D005656:Fungal Proteins / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D005800:Genes, Fungal / Q000235:genetics*; D005816:Genetic Complementation Test; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009154:Mutation; D011494:Protein Kinases / Q000235:genetics; D017346:Protein Serine-Threonine Kinases; D012331:RNA, Fungal / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D012264:Ribonucleotide Reductases / Q000032:analysis / Q000235:genetics*; D016196:S Phase; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013489:Suppression, Genetic
chemical_list: D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D012264:Ribonucleotide Reductases; D011494:Protein Kinases; C104169:DUN1 protein, S cerevisiae; D064447:Checkpoint Kinase 2; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C067022:RAD53 protein, S cerevisiae