Trypanosoma cruzi non-long terminal repeat retrotransposon codes for a protein that bears two C2H2 zinc finger motifs and is endowed with nucleic acid chaperone activity
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Rodríguez Heras, Sara; López, Manuel C; García Pérez, José Luis; Martín, Sandra L.; Thomas, M. CarmenEditorial
Taylor and Francis
Fecha
2005Referencia bibliográfica
Heras SR, López MC, García-Pérez JL, Martin SL, Thomas MC. The L1Tc C-terminal domain from Trypanosoma cruzi non-long terminal repeat retrotransposon codes for a protein that bears two C2H2 zinc finger motifs and is endowed with nucleic acid chaperone activity. Mol Cell Biol. 2005 Nov;25(21):9209-20. doi: 10.1128/MCB.25.21.9209-9220.2005.
Patrocinador
This work was supported by FIS 01/3148 and RICET C03-04 from Fondo de Investigacio´n Sanitaria, MSC, and BMC2003-00834 from Plan Nacional I D I (MEC), Spain. S.R.H. was supported by an MEC predoctoral fellowship (FPU), J.L.G.-P. was supported by a Fundacio´n Ramo´n Areces predoctoral fellowship, and S.L.M. was supported by NIH grant GM 40367Resumen
L1Tc, a non-long terminal repeat retrotransposon from Trypanosoma cruzi, is a 4.9-kb actively transcribed
element which contains a single open reading frame coding for the machinery necessary for its autonomous
retrotransposition. In this paper, we analyze the protein encoded by the L1Tc 3 region, termed C2-L1Tc, which
contains two zinc finger motifs similar to those present in the TFIIIA transcription factor family. C2-L1Tc
binds nucleic acids with different affinities, such that RNA > tRNA > single-stranded DNA > double-stranded
DNA, without any evidence for sequence specificity. C2-L1Tc also exhibits nucleic acid chaperone activity on
different DNA templates that may participate in the mechanism of retrotransposition of the element. C2-L1Tc
promotes annealing of complementary oligonucleotides, prevents melting of perfect DNA duplexes, and facilitates
the strand exchange between DNAs to form the most stable duplex DNA in competitive displacement
assays. Mapping of regions of C2-L1Tc using specific peptides showed that nucleic acid chaperone activity
required a short basic sequence accompanied by a zinc finger motif or by another basic region such as RRR.
Thus, a short basic polypeptide containing the two C2H2 motifs promotes formation of the most stable duplex
DNA at a concentration only three times higher than that required for C2-L1Tc.