Activation of the E3 ligase function of the BRCA1/BARD1 complex by polyubiquitin chains

TY - JOUR

T1 - Activation of the E3 ligase function of the BRCA1/BARD1 complex by polyubiquitin chains

AU - Mallery, Donna L.

AU - Vandenberg, Cassandra J.

AU - Hiom, Kevin

PY - 2002/12/16

Y1 - 2002/12/16

N2 - Loss of the tumour suppressor BRCA1 results in profound chromosomal instability. The fundamental defect underlying this catastrophic phenotype is not yet known. In vivo, BRCA1 forms a heterodimeric complex with BARD1. Both proteins contain an N-terminal zinc RING-finger domain which confers E3 ubiquitin ligase activity. We have isolated full-length human BRCA1/BARD1 complex and have shown that it has a dual E3 ubiquitin ligase activity. First, it mediates the monoubiquitylation of nucleosome core histones in vitro, including the variant histone H2AX that co-localizes with BRCA1 at sites of DNA damage. Secondly, BRCA1/BARD1 catalyses the formation of multiple polyubiquitin chains on itself. Remarkably, this auto-polyubiquitylation potentiates the E3 ubiquitin ligase activity of the BRCA1/BARD1 complex >20-fold. Even though BRCA1 has been reported to associate with a C-terminal ubiquitin hydrolase, BAP1, this enzyme does not appear to function in the deubiquitylation of the BRCA1/BARD1 complex.

AB - Loss of the tumour suppressor BRCA1 results in profound chromosomal instability. The fundamental defect underlying this catastrophic phenotype is not yet known. In vivo, BRCA1 forms a heterodimeric complex with BARD1. Both proteins contain an N-terminal zinc RING-finger domain which confers E3 ubiquitin ligase activity. We have isolated full-length human BRCA1/BARD1 complex and have shown that it has a dual E3 ubiquitin ligase activity. First, it mediates the monoubiquitylation of nucleosome core histones in vitro, including the variant histone H2AX that co-localizes with BRCA1 at sites of DNA damage. Secondly, BRCA1/BARD1 catalyses the formation of multiple polyubiquitin chains on itself. Remarkably, this auto-polyubiquitylation potentiates the E3 ubiquitin ligase activity of the BRCA1/BARD1 complex >20-fold. Even though BRCA1 has been reported to associate with a C-terminal ubiquitin hydrolase, BAP1, this enzyme does not appear to function in the deubiquitylation of the BRCA1/BARD1 complex.

KW - BRCA1 protein

KW - Carrier proteins

KW - Catalysis

KW - DNA damage

KW - Electrophoresis, Polyacrylamide Gel

KW - Enzyme activation

KW - Genetic vectors

KW - Histones

KW - Humans

KW - Protein binding

KW - Protein structure, Tertiary

KW - Recombinant proteins

KW - Substrate specificity

KW - Tumor suppressor proteins

KW - Ubiquitin

KW - Ubiquitin-protein ligases

KW - Zinc fingers

U2 - 10.1093/emboj/cdf691

DO - 10.1093/emboj/cdf691

M3 - Article

C2 - 12485996

SN - 0261-4189

VL - 21

SP - 6755

EP - 6762

JO - EMBO Journal

JF - EMBO Journal

IS - 24

ER -