Conservation of structure and function of DNA replication protein A in the trypanosomatid Crithidia fasciculata.
Human replication protein A (RP-A) is a three-subunit protein that is required for simian virus 40 (SV40) replication in vitro. The trypanosome homologue of RP-A has been purified from Crithidia fasciculata. It is a 1:1:1 complex of three polypeptides of 51, 28, and 14 kDa, binds single-stranded DNA via the large subunit, and is localized within the nucleus. C. fasciculata RP-A substitutes for human RP-A in the large tumor antigen-dependent unwinding of the SV40 origin of replication and stimulates both DNA synthesis and DNA priming by human DNA polymerase alpha/primase, but it does not support efficient SV40 DNA replication in vitro. This extraordinary conservation of structure and function between human and trypanosome RP-A suggests that the mechanism of DNA replication, at both the initiation and the elongation level, is conserved in organisms that diverged from the main eukaryotic lineage very early in evolution.
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Molecular Biology Institute, University of California, Los Angeles 90024.
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D000818:Animals; D002846:Chromatography, Affinity; D016831:Crithidia fasciculata / Q000235:genetics* / Q000378:metabolism; D004257:DNA Polymerase II / Q000378:metabolism; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances; D051716:Replication Protein A; D013539:Simian virus 40 / Q000235:genetics; D013698:Templates, Genetic
D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; C497167:RPA1 protein, human; D051716:Replication Protein A; D004257:DNA Polymerase II; D004259:DNA-Directed DNA Polymerase