title: Arabidopsis thaliana UBC13: implication of error-free DNA damage tolerance and Lys63-linked polyubiquitylation in plants.
abstract: Ubiquitylation is an important biochemical reaction found in all eukaryotic organisms and is involved in a wide range of cellular processes. Conventional ubiquitylation requires the formation of polyubiquitin chains linked through Lys48 of the ubiquitin, which targets specific proteins for degradation. Recently polyubiquitylation through a noncanonical Lys63 chain has been reported, and is required for error-free DNA damage tolerance (or postreplication repair) in yeast. To date, Ubc13 is the only known ubiquitin-conjugating enzyme (Ubc) capable of catalyzing the Lys63-linked polyubiquitylation reaction and this function requires interaction with the Ubc variant Mms2. No information is available on either Lys63-linked ubiquitylation or error-free damage tolerance in plants. We thus cloned and functionally characterized two Arabidopsis thaliana UBC13 genes, AtUBC13A and AtUBC13B. The two genes are highly conserved with respect to chromosomal structure and protein sequence, suggesting that they are derived from a recent gene duplication event. Both AtUbc13 proteins are able to physically interact with yeast or human Mms2, implying that plants also employ the Lys63-linked polyubiquitylation reaction. Furthermore, AtUBC13 genes are able to functionally complement the yeast ubc13 null mutant for spontaneous mutagenesis and sensitivity to DNA damaging agents, suggesting the existence of an error-free DNA damage tolerance pathway in plants. The AtUBC13 genes appear to express ubiquitously and are not induced by various conditions tested.
authors.affiliation: Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Canada.
authors.forename: Rui
authors.initials: R
authors.lastname: Wen
authors.forename: Lindsay
authors.initials: L
authors.lastname: Newton
authors.forename: Genyi
authors.initials: G
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Xiao
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004249:DNA Damage; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D020440:Gene Duplication; D005816:Genetic Complementation Test; D006801:Humans; D008025:Ligases / Q000378:metabolism; D008239:Lysine / Q000737:chemistry; D008969:Molecular Sequence Data; D025821:Polyubiquitin / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D016415:Sequence Alignment; D044763:Ubiquitin-Conjugating Enzymes / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D005656:Fungal Proteins; D025821:Polyubiquitin; C513137:UBC13A protein, Arabidopsis; C513138:UBC13B protein, Arabidopsis; C114715:UBE2V2 protein, human; D044763:Ubiquitin-Conjugating Enzymes; D008025:Ligases; D008239:Lysine