Structural Biology by NMR: Structure, Dynamics, and Interactions

The function of bio-macromolecules is determined by both their 3D structure and conformational dynamics. These molecules are inherently flexible systems displaying a broad range of dynamics on time-scales from picoseconds to seconds. Nuclear Magnetic Resonance (NMR) spectroscopy has emerged as the method of choice for studying both protein structure and dynamics in solution. Typically, NMR experiments are sensitive both to structural features and to dynamics, and hence the measured data contain information on both. Despite major progress in both experimental approaches and computational methods, obtaining a consistent view of structure and dynamics from experimental NMR data remains a challenge. Molecular dynamics simulations have emerged as an indispensable tool in the analysis of NMR data

Structural investigation of glycan recognition by the ERAD quality control lectin Yos9

Yos9 is an essential component of the endoplasmic reticulum associated protein degradation (ERAD) system that is responsible for removing terminally misfolded proteins from the ER lumen and mediating proteasomal degradation in the cytosol. Glycoproteins that fail to attain their native conformation in the ER expose a distinct oligosaccharide structure, a terminal α1,6-linked mannose residue, that is specifically recognized by the mannose 6-phoshate receptor homology (MRH) domain of Yos9. We have determined the structure of the MRH domain of Yos9 in its free form and complexed with 3α, 6α-mannopentaose. We show that binding is achieved by loops between β-strands performing an inward movement and that this movement also affects the entire β-barrel leading to a twist. These rearrangements may facilitate the processing of client proteins by downstream acting factors. In contrast, other oligosaccharides such as 2α-mannobiose bind weakly with only locally occurring chemical shift changes underscoring the specificity of this substrate selection process within ERAD

Indicadores de depressão do Zulliger no Sistema Compreensivo (ZSC)

Este trabalho teve como objetivo verificar se os indicadores de depressão que compõem a Constelação de Depressão (DEPI) do Rorschach no Sistema Compreensivo (SC) auxiliam no diagnóstico de depressão por meio do Zulliger SC. Participaram 27 pacientes com depressão e 27 não-pacientes, do sexo feminino. Para coleta de dados utilizou-se a SCID-I, questionário de identificação e o Zulliger. O tempo de aplicação dos instrumentos foi de 45 a 100 minutos. Os protocolos foram codificados e recodificados por outra pesquisadora às cegas e eventuais discordâncias foram resolvidas por um terceiro juiz. Após análises estatísticas descritivas, aplicou-se o teste t-student. Dentre as variáveis do DEPI, alcançaram valores significativos FD + V, Sum-SH, Índice-egocentricidade, CF + C < FC, Determinantes-mistos e Intelectualização. Conclui-se que o ZSC é um instrumento que pode contribuir no diagnóstico da depressão

Mechanism of TAp73 inhibition by ΔNp63 and structural basis of p63/p73 hetero-tetramerization.

Members of the p53 tumor suppressor family are expressed as multiple isoforms. Isoforms having an N-terminal transactivation domain are transcriptionally active while those ones lacking this domain often inhibit the transcriptional activity of other family members. In squamous cell carcinomas, the high expression level of ΔNp63α inhibits the tumour suppressor function of TAp73β. This can in principle be due to blocking of the promotor or by direct interaction between both proteins. P63 and p73 can hetero oligomerize through their tetramerization domains and a hetero-oligomer consisting of two p63 and two p73 molecules is thermodyna mically more stable than both homo tetramers. Here we show that hetero tetramer complexes exist also in differentiating keratinocytes. Through structure determination of the hetero tetramer we reveal why this hetero tetramer is the thermodynamically prefer red species. Based on this structure we have created mutants that either enable the formation of only heterotetramers or only homotetramers, allowing to investigate the function of these heterotetramers. Using these tools we show that inhibition of TAp73β in squamous cell carcinomas is due to promotor squelching and not direct interaction

Mechanism of TAp73 inhibition by ΔNp63 and structural basis of p63/p73 hetero-tetramerization.

Members of the p53 tumor suppressor family are expressed as multiple isoforms. Isoforms having an N-terminal transactivation domain are transcriptionally active while those ones lacking this domain often inhibit the transcriptional activity of other family members. In squamous cell carcinomas, the high expression level of ΔNp63α inhibits the tumour suppressor function of TAp73β. This can in principle be due to blocking of the promotor or by direct interaction between both proteins. P63 and p73 can hetero oligomerize through their tetramerization domains and a hetero-oligomer consisting of two p63 and two p73 molecules is thermodyna mically more stable than both homo tetramers. Here we show that hetero tetramer complexes exist also in differentiating keratinocytes. Through structure determination of the hetero tetramer we reveal why this hetero tetramer is the thermodynamically prefer red species. Based on this structure we have created mutants that either enable the formation of only heterotetramers or only homotetramers, allowing to investigate the function of these heterotetramers. Using these tools we show that inhibition of TAp73β in squamous cell carcinomas is due to promotor squelching and not direct interaction