Verificação da formação de complexos protéicos nos telômeros de L. amazonensis
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2010-05-21
Autores
Moraes, Camila Esteves de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Na maioria dos eucariotos, proteínas que ligam aos telomeros, tais como POT1 e TRF2 apresentam papéis cruciais na biologia dos telômeros, interagindo com vários outros reguladores dos telômeros para garantir a manutenção adequada dos mesmos e ainda formam complexos de ordem maior, conhecido como telosome ou shelterin. Os telômeros de Leishmania spp. são compostos por repetições conservadas TTAGGG e são mantidos pela telomerase. A base do complexo de proteínas teloméricas de Leishmania é formado pelas proteínas LaRPA-1 e LaRbp38, que ligam vitro e in vivo, com alta afinidade a DNA telomérico simples fita rico em G, e por proteínas que interagem com a região de DNA telemérico dupla fita, como a proteína recentemente descrita, homólogo de TRF. O genoma de Leishmania spp., como outros tripanossomatídeos, não tem muitas das proteínas conservadas que ligam a simplesfita teloméricos encontrada em eucariontes, tais como os homólogos da proteína CDC13 e POT1. Portanto, nós especulamos que o homólogo de RPA-1 de Leishmania pode desempenhar as mesmas funções como POT1/CDC13 nos telômeros do parasita, embora possa se ligar ao DNA telomérico simples fita com alta afinidade e de forma independente de seqüência. LaRPA-1, juntamente com a proteína multifuncional LaRbp38, que também interage com uma ampla gama de seqüências rico em GT, incluindo os telômeros, parece fazer parte de um complexo telomérico parasita que se assemelha ao complexo CST recentemente descrito. O complexo CST está sendo considerado um segundo modo de proteger os telômeros presentes em umavariedade de espécies, com exceção de leveduras de brotamento, e é constituído principalmente por proteínas RPA-like. Neste estudo, nós usamos diferentes abordagens para demonstrar que LaRPA-1 interage com o LaRbp38 e com a...
In most eukaryotes, telomere binding proteins such as POT1 and TRF2 play crucial roles in telomere biology by interacting with several other telomere regulators to ensure proper telomere maintenance and to form high order complexes known as telosome or shelterin. Leishmania spp. telomeres are composed by the conserved TTAGGG repeats which are maintained by telomerase. The basic Leishmania telomeric protein complex is formed by the proteins LaRPA-1 and LaRbp38, which bind in vitro and in vivo, with high affinity, to the G-rich single-stranded DNA, and by proteins that interact with the double-stranded region of telomeres such as the recently described TRF homologue. The Leishmania spp. genome, like other trypanosomatid, lacks many of the conserved single-stranded telomeric proteins found in other eukaryotes, such as the CDC13 and POT1 protein homologues. Thus, we speculate that the Leishmania RPA-1 homologue may play the same roles as POT1/CDC13 at parasite telomeres, although it can also bind to other single-stranded DNA with high affinity and in a sequence-independent manner. LaRPA-1 together with the multifunctional LaRbp38 protein, which also interacts with a wide range of GT-rich sequences, including telomeres, seems to form part of a parasite telomeric complex that resembles the recently described CST complex. The CST complex is being considered a second telomere capping mode occurring in a broad variety of species, except budding yeast, and is mainly formed by RPA-like proteins. In this report we used different approaches to show that LaRPA-1 interacts with both LaRbp38 and with telomerase, and that these protein:protein interactions seem to occur in a cell-cycle independent manner. In addition, LaRPA-1 partially co-localizes with both proteins, probably... (Complete abstract click electronic access below)
In most eukaryotes, telomere binding proteins such as POT1 and TRF2 play crucial roles in telomere biology by interacting with several other telomere regulators to ensure proper telomere maintenance and to form high order complexes known as telosome or shelterin. Leishmania spp. telomeres are composed by the conserved TTAGGG repeats which are maintained by telomerase. The basic Leishmania telomeric protein complex is formed by the proteins LaRPA-1 and LaRbp38, which bind in vitro and in vivo, with high affinity, to the G-rich single-stranded DNA, and by proteins that interact with the double-stranded region of telomeres such as the recently described TRF homologue. The Leishmania spp. genome, like other trypanosomatid, lacks many of the conserved single-stranded telomeric proteins found in other eukaryotes, such as the CDC13 and POT1 protein homologues. Thus, we speculate that the Leishmania RPA-1 homologue may play the same roles as POT1/CDC13 at parasite telomeres, although it can also bind to other single-stranded DNA with high affinity and in a sequence-independent manner. LaRPA-1 together with the multifunctional LaRbp38 protein, which also interacts with a wide range of GT-rich sequences, including telomeres, seems to form part of a parasite telomeric complex that resembles the recently described CST complex. The CST complex is being considered a second telomere capping mode occurring in a broad variety of species, except budding yeast, and is mainly formed by RPA-like proteins. In this report we used different approaches to show that LaRPA-1 interacts with both LaRbp38 and with telomerase, and that these protein:protein interactions seem to occur in a cell-cycle independent manner. In addition, LaRPA-1 partially co-localizes with both proteins, probably... (Complete abstract click electronic access below)
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Leishmania, Genética, Proteínas
Como citar
MORAES, Camila Esteves de. Verificação da formação de complexos protéicos nos telômeros de L. amazonensis. 2010. 50 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências de Botucatu, 2010.