Linear consensus motifs are short contiguous sequences of residues within a protein that can form recognition modules for protein interaction or catalytic modification. Protein kinase specificity and ...the matching of kinases to substrates have been mostly defined by phosphorylation sites that occur in linear consensus motifs. However, phosphorylation can also occur within sequences that do not match known linear consensus motifs recognized by kinases and within flexible loops. We report the identification of Thr(253) in α-tubulin as a site that is phosphorylated by protein kinase C βI (PKCβI). Thr(253) is not part of a linear PKC consensus motif. Instead, Thr(253) occurs within a region on the surface of α-tubulin that resembles a PKC phosphorylation site consensus motif formed by basic residues in different parts of the protein, which come together in the folded protein to form the recognition motif for PKCβI. Mutations of these basic residues decreased substrate phosphorylation, confirming the presence of this "structurally formed" consensus motif and its importance for the protein kinase-substrate interaction. Analysis of previously reported protein kinase A (PKA) and PKC substrates identified sites within structurally formed consensus motifs in many substrates of these two kinase families. Thus, the concept of consensus phosphorylation site motif needs to be expanded to include sites within these structurally formed consensus motifs.
Parasitic diseases cause ∼500,000 deaths annually and remain a major challenge for therapeutic development. Using a rational design based approach, we developed peptide inhibitors with anti-parasitic ...activity that were derived from the sequences of parasite scaffold proteins LACK (Leishmania's receptor for activated C-kinase) and TRACK (Trypanosomareceptor for activated C-kinase). We hypothesized that sequences in LACK and TRACK that are conserved in the parasites, but not in the mammalian ortholog, RACK (Receptor for activated C-kinase), may be interaction sites for signaling proteins that are critical for the parasites' viability. One of these peptides exhibited leishmanicidal and trypanocidal activity in culture. Moreover, in infected mice, this peptide was also effective in reducing parasitemia and increasing survival without toxic effects. The identified peptide is a promising new anti-parasitic drug lead, as its unique features may limit toxicity and drug-resistance, thus overcoming central limitations of most anti-parasitic drugs.
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•Identified unique short sequences conserved in parasite but not in host orthologue.•Peptides corresponding to these sequences are active anti-parasitic drug lead.•Cyclization of the peptides generates drug leads for in vivo proof of concept.
Protein kinase C (PKC) plays a key role in embryonic stem cell (ESC) proliferation, self-renewal, and differentiation. However, the function of specific PKC isoenzymes have yet to be determined. Of ...the PKCs expressed in undifferentiated ESCs, βIPKC was the only isoenzyme abundantly expressed in the nuclei. To investigate the role of βΙPKC in these cells, we employed a phosphoproteomics strategy and used two classical (cPKC) peptide modulators and one βIPKC-specific inhibitor peptide. We identified 13 nuclear proteins that are direct or indirect βΙPKC substrates in undifferentiated ESCs. These proteins are known to be involved in regulating transcription, splicing, and chromatin remodeling during proliferation and differentiation. Inhibiting βΙPKC had no effect on DNA synthesis in undifferentiated ESCs. However, upon differentiation, many cells seized to express βΙPKC and βΙPKC was frequently found in the cytoplasm. Taken together, our results suggest that βIPKC takes part in the processes that maintain ESCs in their undifferentiated state.
A hipótese de que peptídeos gerados como produtos de proteólise intracelular poderiam modular cascatas de sinalização, foi originalmente proposto pelo nosso grupo. Um estudo realizado por Heimann et ...al. (2005) mostrou que camundongos geneticamente modificados e submetidos à dieta hiperlipídica, apresentavam uma diferença no conteúdo intracelular de peptídeos e uma melhora da resistência à insulina. Neste trabalho, investigamos o conteúdo peptídico intracelular do tecido adiposo de animais que desenvolveram obesidade e resistência à insulina, após serem submetidos à dieta cafeteria. Duas sequências peptídicas apresentaram 100% de aumento no tecido adiposo de animais submetidos à dieta cafeteria, em relação aos controles, tendo sido analisadas por ensaios de cinética enzimática, captação de glicose, western blot e cromatografia de afinidade. Os resultados obtidos corroboram os dados de Heimann et al. (2005) de que peptídeos intracelulares podem estar envolvidos na resistência à insulina, modulando o transporte de glicose no tecido adiposo.
The hypothesis that peptides generated as degradation products of intracellular proteolyses could modulate signaling pathways, was originally proposed by our group. A study by Heimann et al. (2005) showed that mice genetically modified and fed with high-fat diet, showed a difference in intracellular content of peptides and an improvement of insulin resistance. In this study, we investigated the intracellular peptide content from adipose tissue of animals that developed obesity and insulin resistance after being treated with the Western diet. Two peptide sequences showed 100% increase in adipose tissue of animals submitted to the Western diet compared to controls, and were analyzed by enzymatic assays, glucose uptake, western blot and affinity chromatography. Altogether, these results corroborate previous suggestions that intracellular peptides may be involved in insulin resistance, modulating glucose transport in adipose tissue.
O feijão comum (Phaseolus vulgaris L.) é uma fabaceae de grande importância agrícola e alimentar, por ser fonte de proteínas, vitaminas, ferro e sais minerais, tornando-se um importante alimento na ...dieta básica da população brasileira. Foram inseridas as rizobactérias promotoras do crescimento de plantas – RPCP, dentre elas o Bacillus subtilis. Mediante a importância da utilização dessas rizobactérias o objetivo do trabalho foi o de avaliar a produtividade de cultivares de feijão sob doses de um produto a base de Bacillus subtilis. Os dados foram submetidos à análise de variância e quando constatada significância, foram avaliadas as seguintes variáveis: número de vagens por planta, número de grãos por planta, número de grãos por vagem, massa de 100 grãos, rendimento de grãos e teor de clorofila. As analises foram processadas com auxílio do software SISVAR. Com base nos resultados obtidos neste estudo, pode-se concluir que a aplicação de doses crescentes de Bacillus subtilis via adubação foliar, influenciou nos componentes de rendimento e na produtividade de feijão comum. A utilização da cultivar BRS FC 402 se destacou em relação ao número de semente/vagem, número de semente/planta e massa de 1000 grãos, indicando a importância da seleção adequada de cultivares para melhorar a produtividade. Essa cultivar é adaptada às principais regiões produtoras, testada e aprovada pela indústria (EMBRAPA, 2018).
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