Regulation of UMSBP activities through redox-sensitive protein domains.
UMSBP is a CCHC-type zinc finger protein, which functions during replication initiation of kinetoplast DNA minicircles and the segregation of kinetoplast DNA networks. Interactions of UMSBP with origin sequences, as well as the protein oligomerization, are affected by its redox state. Reduction yields UMSBP monomers and activates its binding to DNA, while oxidation drives UMSBP oligomerization and impairs its DNA-binding activity. Kinetics analyses of UMSBP-DNA interactions revealed that redox affects the association of free UMSBP with the DNA, but has little effect on its dissociation from the nucleoprotein complex. A previously proposed model, suggesting that binding of DNA is regulated via the reversible interconversions of active UMSBP monomers and inactive oligomers, was challenged here, revealing that the two redox-driven processes are not interrelated. No correlation could be observed between DNA-binding inhibition and UMSBP oligomerization, upon oxidation of UMSBP. Moreover, while the presence of zinc ions was found to be essential for the interaction of UMSBP with DNA, UMSBP oligomerization occurred through zinc-depleted, unfolded zinc finger domains. Site directed mutagenesis analysis of UMSBP suggested that its unique methionine residue, which can be oxidized into methionine sulfoxide, is not involved in the redox-mediated regulation of UMSBP-DNA interactions.
Sela
Dotan
D
Department of Parasitology, Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University, Hadassah Medical School, Jerusalem, Israel.
Shlomai
Joseph
J
D000595:Amino Acid Sequence; D000818:Animals; D016831:Crithidia fasciculata / Q000235:genetics / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry; D018105:DNA, Kinetoplast / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D008715:Methionine / Q000737:chemistry; D008969:Molecular Sequence Data; D009698:Nucleoproteins / Q000378:metabolism; D010084:Oxidation-Reduction; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism; D018741:Replication Origin; D017386:Sequence Homology, Amino Acid; D016335:Zinc Fingers
D018105:DNA, Kinetoplast; D004268:DNA-Binding Proteins; D009698:Nucleoproteins; D015800:Protozoan Proteins; C095676:universal minicircle sequence binding protein, protozoan; D008715:Methionine; D003545:Cysteine