Identification of Plasmodium falciparum DNA Repair Protein Mre11 with an Evolutionarily Conserved Nuclease Function.
The eukaryotic Meiotic Recombination protein 11 (Mre11) plays pivotal roles in the DNA damage response (DDR). Specifically, Mre11 senses and signals DNA double strand breaks (DSB) and facilitates their repair through effector proteins belonging to either homologous recombination (HR) or non-homologous end joining (NHEJ) repair mechanisms. In the human malaria parasite Plasmodium falciparum, HR and alternative-NHEJ have been identified; however, little is known about the upstream factors involved in the DDR of this organism. In this report, we identify a putative ortholog of Mre11 in P. falciparum (PfalMre11) that shares 22% sequence similarity to human Mre11. Homology modeling reveals striking structural resemblance of the predicted PfalMre11 nuclease domain to the nuclease domain of Saccharomyces cerevisiae Mre11 (ScMre11). Complementation analyses reveal functional conservation of PfalMre11 nuclease activity as demonstrated by the ability of the PfalMre11 nuclease domain, in conjunction with the C-terminal domain of ScMre11, to functionally complement an mre11 deficient yeast strain. Functional complementation was virtually abrogated by an amino acid substitution in the PfalMre11 nuclease domain (D398N). PfalMre11 is abundant in the mitotically active trophozoite and schizont stages of P. falciparum and is up-regulated in response to DNA damage, suggesting a role in the DDR. PfalMre11 exhibits physical interaction with PfalRad50. In addition, yeast 2-hybrid studies show that PfalMre11 interacts with ScRad50 and ScXrs2, two important components of the well characterized Mre11-Rad50-Xrs2 complex which is involved in DDR signaling and repair in S. cerevisiae, further supporting a role for PfalMre11 in the DDR. Taken together, these findings provide evidence that PfalMre11 is an evolutionarily conserved component of the DDR in Plasmodium.
Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India.
Sugith Babu
SB
Badugu
Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India.
Shaik Abdul
SA
Nabi
Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India.
Pratap
P
Vaidyam
Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India.
Shyamasree
S
Laskar
Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India.
Sunanda
S
Bhattacharyya
Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India.
Mrinal Kanti
MK
Bhattacharyya
D000595:Amino Acid Sequence; D000913:Antibodies, Protozoan / Q000276:immunology; D005075:Biological Evolution; D004249:DNA Damage; D059766:DNA End-Joining Repair; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D004912:Erythrocytes / Q000469:parasitology; D005786:Gene Expression Regulation; D005816:Genetic Complementation Test; D006801:Humans; D008018:Life Cycle Stages; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D015800:Protozoan Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D011994:Recombinant Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D000913:Antibodies, Protozoan; D004268:DNA-Binding Proteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins