AUTHOR=Guo Huiping , Wen Rui , Liu Zhi , Datla Raju , Xiao Wei 

TITLE=Molecular Cloning and Functional Characterization of Two Brachypodium distachyon UBC13 Genes Whose Products Promote K63-Linked Polyubiquitination

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.01222

DOI=10.3389/fpls.2015.01222

ISSN=1664-462X

ABSTRACT=<p>Living organisms are constantly subject to DNA damage from environmental sources. Due to the sessile nature of plants, UV irradiation is a major genotoxic agent and imposes a significant threat on plant survival, genome stability and crop yield. In addition, other environmental chemicals can also influence the stability of the plant genome. Eukaryotic organisms have evolved a mechanism to cope with replication-blocking lesions and stabilize the genome. This mechanism is known as error-free DNA damage tolerance, and is mediated by K63-linked PCNA polyubiquitination. Genes related to K63-linked polyubiquitination have been isolated recently from model plants like <italic>Arabidopsis</italic> and rice, but we are unaware of such reports on the crop model <italic>Brachypodium distachyon</italic>. Here, we report the identification and functional characterization of two <italic>B. distachyon UBC13</italic> genes. Both Ubc13s form heterodimers with Uevs from other species, which are capable of catalyzing K63 polyubiquitination <italic>in vitro</italic>. Both genes can functionally rescue the yeast <italic>ubc13</italic> null mutant from killing by DNA-damaging agents. These results suggest that Ubc13-Uev-promoted K63-linked polyubiquitination is highly conserved in eukaryotes including <italic>B. distachyon.</italic> Consistent with recent findings that K63-linked polyubiquitination is involved in several developmental and stress-responsive pathways, the expression of <italic>BdUbc13</italic>s appears to be constitutive and is regulated by abnormal temperatures.</p>