A Draft of the Human Septin Interactome

Background: Septins belong to the GTPase superclass of proteins and have been functionally implicated in cytokinesis and the maintenance of cellular morphology. They are found in all eukaryotes, except in plants. In mammals, 14 septins have been described that can be divided into four groups. It has been shown that mammalian septins can engage in homo- and heterooligomeric assemblies, in the form of filaments, which have as a basic unit a hetero-trimeric core. In addition, it has been speculated that the septin filaments may serve as scaffolds for the recruitment of additional proteins. Methodology/Principal Findings: Here, we performed yeast two-hybrid screens with human septins 1-10, which include representatives of all four septin groups. Among the interactors detected, we found predominantly other septins, confirming the tendency of septins to engage in the formation of homo- and heteropolymeric filaments. Conclusions/Significance: If we take as reference the reported arrangement of the septins 2, 6 and 7 within the heterofilament, (7-6-2-2-6-7), we note that the majority of the observed interactions respect the ""group rule"", i.e. members of the same group (e. g. 6, 8, 10 and 11) can replace each other in the specific position along the heterofilament. Septins of the SEPT6 group preferentially interacted with septins of the SEPT2 group (p<0.001), SEPT3 group (p<0.001) and SEPT7 group (p<0.001). SEPT2 type septins preferentially interacted with septins of the SEPT6 group (p<0.001) aside from being the only septin group which interacted with members of its own group. Finally, septins of the SEPT3 group interacted preferentially with septins of the SEPT7 group (p<0.001). Furthermore, we found non-septin interactors which can be functionally attributed to a variety of different cellular activities, including: ubiquitin/sumoylation cycles, microtubular transport and motor activities, cell division and the cell cycle, cell motility, protein phosphorylation/signaling, endocytosis, and apoptosis.Fundao de Amparo a Pesquisa do Estado Sao Paulo (Fapesp)CAPES: Coordenao de Aperfeioamento de Pessoal de Navel SuperiorConselho Nacional de Pesquisa e Desenvolvimento (CNPq)Laboratorio Nacional de Biociencias-Centro Nacional de Pesquisa em Energia e Materais (LNBio-CNPEM

Identification and characterization of proteins that selectively interact with isoforms of the mRNA binding protein AUF1 (hnRNP D)

The mRNAs that encode certain cytokines and protooncogenes frequently contain a typical AU-rich motif that is located in their 3'-untranslated region. The protein AUF1 is the first factor identified that binds to AU-rich regions and mediates the fast degradation of the target mRNAs. AUF1 exists as four different isoforms (p37, p40, p42 and p45) that are generated by alternative splicing. The fact that AUF1 does not degrade mRNA itself had led to the suggestion that other AUF1 interacting proteins might be involved in the process of selective mRNA degradation. Here we used the yeast twohybrid system in order to identify proteins that bind to AUF1. We detected AUF1 itself, as well as the ubiquitinconjugating enzyme E2I and three RNA binding proteins: NSEP-1, NSAP-1 and IMP-2, as AUF1 interacting proteins. We confirmed all interactions in vitro and mapped the protein domains that are involved in the interaction with AUF1. Gelshift assays with the recombinant purified proteins suggest that the interacting proteins and AUF1 can bind simultaneously to an AU-rich RNA oligonucleotide. Most interestingly, the AUF1 interacting protein NSEP-1showed an endoribonuclease activity in vitro. These data suggest the possibility that the identified AUF1 interacting proteins might be involved in the regulation of mRNA stability mediated by AUF1.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.3841253

Analysis of the structural determinants for RNA binding of the human protein AUF1/hnRNP D

The protein AUF1/hnRNP D was one of the first factors identified that binds to the AUrich region of certain mRNAs and mediates their fast degradation. Here we describe experiments to address the structural determinants for the binding of AUF1 to the RNA by combining comparative molecular modeling with gel shift assays. From our model of the RNA binding region of AUF1 we predicted that it interacts with RNA predominantly through stacking interactions that do not provide basespecific recognition. Only two RNA positions bound by AUF1 show base preferences: one for pyrimidine bases and the second for a conserved adenine residue. Gel shift assays with a panel of RNA oligonucleotides largely confirmed these modelbased binding determinants. An alignment with proteins of the hnRNP family demonstrated that the amino acids involved in the stacking interactions are conserved whereas those that confer a basespecific recognition in AUF1 are variable.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.383583183

The role of Opaque2 in the control of lysine-degrading activities in developing maize endosperm

We have isolated a cDNA clone, designated ZLKRSDH, encoding the bifunctional enzyme lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) from maize. The predicted polypeptide has an N-terminal LKR domain and a C-terminal SDH domain that are similar to the yeast LYS1 and LYS9 monofunctional proteins, respectively. The maize LKR/SDH protein is located in the cytoplasm of subaleurone endosperm cell layers. Transcripts and polypeptides as well as enzyme activities showed an upregulation and downregulation during endosperm development. The developmental expression of ZLKRSDH was examined in normal and opaque2 seeds. In the mutant endosperm, mRNA levels were reduced by >90%, with concomitant reductions in polypeptide levels and LKR/SDH activity. These results suggest that lysine levels in the endosperm are likely to be controlled at the transcriptional level by the Opaque2 transcription factor.11101981199

Locus of control and contraceptive knowledge, attitude and practice among university students Locus de control y conocimiento, actitud y práctica contraceptivas entre adolescentes universitarios Lócus de controle e conhecimento, atitude e prática contraceptivas entre adolescentes universitários

OBJECTIVE: To assess the relationship between locus of control and knowledge, attitude and practice regarding pill and condom use among university students. METHODS: The inquiry was developed in Campinas, a city in Southeastern Brazil, in 2006. A total of 295 adolescent newcomers to a public university answered a structured questionnaire and Levenson's multidimensional locus of control scale. The scores of the dimensions of locus of control were calculated and Spearman's correlation coefficient was used to assess their correlation with knowledge and practice concerning pill and condom use. In order to assess the relationship between the dimensions of locus of control and sociodemographic variables and variables related to the individuals' sex life, Kruskal-Wallis and Mann-Whitney tests were used. RESULTS: Male adolescents had higher scores of powerful others externality when compared to female adolescents (p=0.01). Students living alone had lower internality (p=0.01). When locus of control was compared to condom use in the first intercourse, considering only the 102 students who informed the age of the beginning of sexual activity, greater internality was found among male adolescents who did not use condoms (p<0.05). When the locus of control scores were correlated with contraceptive knowledge and practice, it was found that the higher the powerful others externality locus, the lower the adequate use of contraceptive methods (r = -0.22, p=0.03). CONCLUSIONS: The powerful others externality locus influences the practice of contraceptive use in this group of adolescents.<br>OBJETIVO: Evaluar la relación del locus de control con conocimiento, actitud y práctica relacionados a la píldora y al preservativo entre adolescentes estudiantes universitarios. MÉTODOS: Estudio tipo pesquisa desarrollado en Campinas, Sureste de Brasil, en 2006. El total de 295 adolescentes ingresados de una universidad pública respondió a un cuestionario estructurado y a la escala multidimensional de locus de control de Levenson. Fueron calculados los escores de las dimensiones del locus de control y el coeficiente de correlación de Spearman para evaluar la correlación con el conocimiento y la práctica del uso de píldora y preservativo. Para evaluar la relación entre las dimensiones del locus de control y las variables sociodemográficas y variables relacionadas a la vida sexual fueron usadas las pruebas de Kruskal-Wallis y Mann-Whitney. RESULTADOS: Los adolescentes del sexo masculino presentaron mayor externalidad- otros poderosos cuando se compararon con las del sexo femenino (p=0,001). Estudiantes que vivían solos tenían una internalidad más baja (p=0,001). Cuando el locus de control fue comparado con el uso de preservativo en la primera relación sexual, considerándose apenas los 102 estudiantes que informaron la edad de inicio de la actividad sexual, fue encontrada mayor internalidad entre los adolescentes del sexo masculino que no usaron preservativo (p?0,05). Al correlacionar los escores del locus de control con el conocimiento contraceptivo y práctica, se observó que cuanto más elevado el escore del locus de control externalidad otros-poderosos, menor el uso adecuado de métodos contraceptivos (r=-0,22, p=0,03). CONCLUSIONES: El locus externalidad otros-poderosos influencia la práctica de uso de método contraceptivo en ese grupo de adolescentes.<br>OBJETIVO: Avaliar a relação do lócus de controle com conhecimento, atitude e prática relacionados à pílula e ao preservativo entre adolescentes estudantes universitários. MÉTODOS: Estudo tipo inquérito desenvolvido em Campinas, SP, em 2006. O total de 295 adolescentes ingressantes de uma universidade pública respondeu a um questionário estruturado e à escala multidimensional de lócus de controle de Levenson. Foram calculados os escores das dimensões do lócus de controle e o coeficiente de correlação de Spearman para avaliar a correlação com o conhecimento e a prática do uso de pílula e preservativo. Para avaliar a relação entre as dimensões do lócus de controle e as variáveis sociodemográficas e variáveis relacionadas à vida sexual foram usados os testes de Kruskal-Wallis e Mann-Whitney. RESULTADOS: Os adolescentes do sexo masculino apresentaram maior externalidade-outros poderosos quando comparados com as do sexo feminino (p=0,01). Estudantes que viviam sozinhos tinham uma internalidade mais baixa (p=0,01). Quando o lócus de controle foi comparado com o uso de preservativo na primeira relação sexual, considerando-se apenas os 102 estudantes que informaram a idade de início da atividade sexual, foi encontrada maior internalidade entre os adolescentes do sexo masculino que não usaram preservativo (p<0,05). Ao correlacionar os escores do lócus de controle com o conhecimento contraceptivo e prática, observou-se que quanto mais elevado o escore do lócus de controle externalidade outros-poderosos, menor o uso adequado de métodos contraceptivos (r = -0,22, p=0.03). CONCLUSÕES: O lócus externalidade outros-poderosos influencia a prática de uso de método contraceptivo nesse grupo de adolescentes

Aromatic side-chain conformational switch on the surface of the RNA Recognition Motif enables RNA discrimination

The RNA Recognition Motif (RRM) is the most ubiquitous RNA binding domain. Here the authors combined NMR and molecular dynamics simulations and show that the RRM RNA binding surface exists in different states and that a conformational switch of aromatic side-chains fine-tunes sequence specific binding affinities