DNA polymerase beta from Trypanosoma cruzi is involved in kinetoplast DNA replication and repair of oxidative lesions

详细信息    查看全文

• 作者：Bruno Luiz Fonseca Schamber-Reis^a ; ^d ; Sheila Nardelli^b ; Carlos Gustavo Ré ; gis-Silva^a ; Priscila Carneiro Campos^a ; Paula Gonç ; alves Cerqueira^a ; Sabrina Almeida Lima^a ; Gló ; ria Regina Franco^a ; Andrea Mara Macedo^a ; Sergio Danilo Junho Pena^a ; Christophe Cazaux^e ; Jean-Sé ; bastien Hoffmann^e ; Maria Cristina Machado Motta^c ; Sergio Schenkman^b ; Santuza Maria Ribeiro Teixeira^a ; Carlos Renato Machado^a ; ^{crmachad@icb.ufmg.br}
• 关键词：DNA repair ; Trypanosoma cruzi ; Oxidative stress ; Oxoguanine ; Kinetoplast
• 刊名：Molecular and Biochemical Parasitology
• 出版年：2012
• 出版时间：June, 2012
• 年：2012
• 卷：183
• 期：2
• 页码：122-131
• 全文大小：951 K

文摘

Specific DNA repair pathways from Trypanosoma cruzi are believed to protect genomic DNA and kinetoplast DNA (kDNA) from mutations. Particular pathways are supposed to operate in order to repair nucleotides oxidized by reactive oxygen species (ROS) during parasite infection, being 7,8-dihydro-8-oxoguanine (8oxoG) a frequent and highly mutagenic base alteration. If unrepaired, 8oxoG can lead to cytotoxic base transversions during DNA replication. In mammals, DNA polymerase beta (Pol¦Â) is mainly involved in base excision repair (BER) of oxidative damage. However its biological role in T. cruzi is still unknown. We show, by immunofluorescence localization, that T. cruzi DNA polymerase beta (Tcpol¦Â) is restricted to the antipodal sites of kDNA in replicative epimastigote and amastigote developmental stages, being strictly localized to kDNA antipodal sites between G1/S and early G2 phase in replicative epimastigotes. Nevertheless, this polymerase was detected inside the mitochondrial matrix of trypomastigote forms, which are not able to replicate in culture. Parasites over expressing Tcpol¦Â showed reduced levels of 8oxoG in kDNA and an increased survival after treatment with hydrogen peroxide when compared to control cells. However, this resistance was lost after treating Tcpol¦Â overexpressors with methoxiamine, a potent BER inhibitor. Curiously, a presumed DNA repair focus containing Tcpol¦Â was identified in the vicinity of kDNA of cultured wild type epimastigotes after treatment with hydrogen peroxide. Taken together our data suggest participation of Tcpol¦Â during kDNA replication and repair of oxidative DNA damage induced by genotoxic stress in this organelle.