RESUMO
BACKGROUND: The initiation of translation in eukaryotes is supported by the action of several eukaryotic Initiation Factors (eIFs). The largest of these is eIF3, comprising of up to thirteen polypeptides (eIF3a through eIF3m), involved in multiple stages of the initiation process. eIF3 has been better characterized from model organisms, but is poorly known from more diverged groups, including unicellular lineages represented by known human pathogens. These include the trypanosomatids (Trypanosoma and Leishmania) and other protists belonging to the taxonomic supergroup Excavata (Trichomonas and Giardia sp.). RESULTS: An in depth bioinformatic search was carried out to recover the full content of eIF3 subunits from the available genomes of L. major, T. brucei, T. vaginalis and G. duodenalis. The protein sequences recovered were then submitted to homology analysis and alignments comparing them with orthologues from representative eukaryotes. Eleven putative eIF3 subunits were found from both trypanosomatids whilst only five and four subunits were identified from T. vaginalis and G. duodenalis, respectively. Only three subunits were found in all eukaryotes investigated, eIF3b, eIF3c and eIF3i. The single subunit found to have a related Archaean homologue was eIF3i, the most conserved of the eIF3 subunits. The sequence alignments revealed several strongly conserved residues/region within various eIF3 subunits of possible functional relevance. Subsequent biochemical characterization of the Leishmania eIF3 complex validated the bioinformatic search and yielded a twelfth eIF3 subunit in trypanosomatids, eIF3f (the single unidentified subunit in trypanosomatids was then eIF3m). The biochemical data indicates a lack of association of the eIF3j subunit to the complex whilst highlighting the strong interaction between eIF3 and eIF1. CONCLUSIONS: The presence of most eIF3 subunits in trypanosomatids is consistent with an early evolution of a fully functional complex. Simplified versions in other excavates might indicate a primordial complex or secondary loss of selected subunits, as seen for some fungal lineages. The conservation in eIF3i sequence might indicate critical functions within eIF3 which have been overlooked. The identification of eIF3 subunits from distantly related eukaryotes provides then a basis for the study of conserved/divergent aspects of eIF3 function, leading to a better understanding of eukaryotic translation initiation.
Assuntos
Fator de Iniciação 3 em Eucariotos/química , Fator de Iniciação 3 em Eucariotos/genética , Trichomonadida/genética , Trypanosoma/genética , Sequência de Aminoácidos , Animais , Biologia Computacional , Sequência Conservada , Evolução Molecular , Variação Genética , Genoma de Protozoário , Humanos , Dados de Sequência Molecular , Filogenia , Subunidades Proteicas/química , Subunidades Proteicas/genética , Alinhamento de SequênciaRESUMO
It is hypothesized that apples of 2 Brazilian cultivars with different content of sugars and antioxidant compounds promote similar effects on the antioxidant status and lipid peroxidation in human serum after acute intake. Nine healthy women ingested 300 mL of Golden Delicious or Catarina apple juice (AJ) or water, and blood samples were collected before and 1 hour after intake. After intake of both AJ, a similar and significant increase in serum antioxidant capacity and ascorbic and uric acid levels and a significant decrease in serum lipid peroxidation was observed. The increase in serum antioxidant capacity after consumption of both AJ was correlated directly with the uric acid levels and inversely with serum lipid peroxidation. In summary, the acute intake of AJ of 2 cultivars promoted a similar effect on the antioxidant status and lipid peroxidation in human blood serum.
