DNA-PKcs regulates a single-stranded DNA endonuclease activity of Artemis.
Human nuclease Artemis belongs to the metallo-beta-lactamase protein family. It acquires double-stranded DNA endonuclease activity in the presence of DNA-PKcs. This double-stranded DNA endonuclease activity is critical for opening DNA hairpins in V(D)J recombination and is thought to be important for processing overhangs during the nonhomologous DNA end joining (NHEJ) process. Here we show that purified human Artemis exhibits single-stranded DNA endonuclease activity. This activity is proportional to the amount of highly purified Artemis from a gel filtration column. The activity is stimulated by DNA-PKcs and modulated by purified antibodies raised against Artemis. Moreover, the divalent cation-dependence and sequence-dependence of this single-stranded endonuclease activity is the same as the double-stranded DNA endonuclease activity of Artemis:DNA-PKcs. These findings further expand the range of DNA substrates upon which Artemis and Artemis:DNA-PKcs can act. The findings are discussed in the context of NHEJ.
Gu
Jiafeng
J
Department of Pathology, Norris Comprehensive Cancer Center, Los Angeles, CA 90089, USA.
Li
Sicong
S
Zhang
Xiaoshan
X
Wang
Ling-Chi
LC
Niewolik
Doris
D
Schwarz
Klaus
K
Legerski
Randy J
RJ
Zandi
Ebrahim
E
Lieber
Michael R
MR
D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002460:Cell Line; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins; D003850:Deoxyribonuclease I / Q000378:metabolism*; D004720:Endonucleases; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*
C109198:CIB1 protein, human; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C426344:DCLRE1C protein, human; D004720:Endonucleases; D003850:Deoxyribonuclease I; D011088:DNA Ligases; D000072481:DNA Ligase ATP