Biochemical analysis of TssK, a core component of the bacterial Type VI secretion system, reveals distinct oligomeric states of TssK and identifies a TssK–TssFG subcomplex

Gram-negative bacteria use the Type VI secretion system (T6SS) to inject toxic proteins into rival bacteria or eukaryotic cells. However, the mechanism of the T6SS is incompletely understood. In the present study, we investigated a conserved component of the T6SS, TssK, using the antibacterial T6SS of Serratia marcescens as a model system. TssK was confirmed to be essential for effector secretion by the T6SS. The native protein, although not an integral membrane protein, appeared to localize to the inner membrane, consistent with its presence within a membrane-anchored assembly. Recombinant TssK purified from S. marcescens was found to exist in several stable oligomeric forms, namely trimer, hexamer and higher-order species. Native-level purification of TssK identified TssF and TssG as interacting proteins. TssF and TssG, conserved T6SS components of unknown function, were required for T6SS activity, but not for correct localization of TssK. A complex containing TssK, TssF and TssG was subsequently purified in vitro, confirming that these three proteins form a new subcomplex within the T6SS. Our findings provide new insight into the T6SS assembly, allowing us to propose a model whereby TssK recruits TssFG into the membrane-associated T6SS complex and different oligomeric states of TssK may contribute to the dynamic mechanism of the system

Evaluation of total and bioaccessible concentration of minerals in creole beans.

The present study evaluated the total and bioaccessible concentrations of minerals in raw and cooked Creole beans. An analytical methodology was optimized, which involved several steps from sample preparation, accuracy study, data treatment, and instrumental analysis ? using a microwave-induced plasma optical emission spectrometer (MIP OES). The present study provides information about the total concentration of the metals Ba, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Pb, Zn and the bioaccessible fraction of metals Ba, Cu, Fe, Mn, Pb and Zn in three different types of creole beans. The elements that presented a greater quantity on all beans, both raw and cooked, were K and Mg. K varied from 12,600 to 13,300 mg/kg for the raw beans and 4590?10300 mg/kg for the cooked beans. Mg varied between 1620 and 1980 mg/kg for the raw beans and 670?1040 mg/kg for the cooked beans. The BRS Expedito type showed a higher concentration of K and Mg on raw and cooked beans. However, when the bioaccessibility study was carried out among the elements listed above, the most bioaccessible were Cu and Zn. Cu presented a bioaccessible fraction percentage between 52.6?59.2% for raw beans and 38.5?61.2% for cooked beans. Zn presented a bioaccessible fraction percentage between 45.6?50.6% for raw beans and 43%?63.5% for cooked beans. The results found on this study indicate that, possibly, the water and the cooking process significantly influences the mineral content. Also, studying mineral concentration on cooked beans is more nutritionally important than characterizing the raw grain, as beans are a type of food mostly consumed on its cooked form

SEED TREATMENT: IMPORTANCE OF PRODUCTS AND EQUIPMENT

O tratamento de sementes é essencial e benéfico para todas as culturas, onde o objetivo é eliminar, controlar ou repelir fungos, insetos e outras pragas que atacam sementes, mudas e plantas. Esta revisão tem como objetivo mostrar os tipos de tratamento de sementes e os diferentes equipamentos agrícolas utilizados para realizar este tipo de tratamento. Este estudo ocorreu entre os meses de outubro e novembro deste ano, e pode-se perceber nos resultados que a demanda por tratamento de sementes no Brasil tem aumentado em relação ao uso de fungicidas e tecnologias e equipamentos de aplicação, onde pode-se concluir que o tratamento de sementes está em constante evolução, tanto no que diz respeito aos equipamentos de tratamento de sementes quanto aos produtos químicos e biológicos utilizados

Unexpected Occurrence of Plasmid-Mediated Quinolone Resistance Determinants in Environmental Aeromonas spp.

Identification of plasmid-mediated qnr genes outside Enterobacteriaceae underlines a possible diffusion of those resistance determinants within gram-negative rods

MARKET AND PRODUCTION OF AGROECOLOGICAL SEEDS

In recent decades, agriculture has been changing mainly in terms of organic production, consumption and market. This increase is due to people's interest in pesticide-free products that meet all environmental, cultural and social issues, presenting itself as a highly competitive and lucrative market niche. For this reason, this bibliographic review aims to describe the market scenario and the production of agroecological seeds, in addition to characterizing the production of organic seeds and evaluating the potential of this market niche, which is increasingly the target of investments and demand for food. , but it is important to have more studies about it, as well as specific legislation for organic seeds

Genetic Analysis of Anti-Amoebae and Anti-Bacterial Activities of the Type VI Secretion System in Vibrio cholerae

A type VI secretion system (T6SS) was recently shown to be required for full virulence of Vibrio cholerae O37 serogroup strain V52. In this study, we systematically mutagenized each individual gene in T6SS locus and characterized their functions based on expression and secretion of the hemolysin co-regulated protein (Hcp), virulence towards amoebae of Dictyostelium discoideum and killing of Escherichia coli bacterial cells. We group the 17 proteins characterized in the T6SS locus into four categories: twelve (VipA, VipB, VCA0109–VCA0115, ClpV, VCA0119, and VasK) are essential for Hcp secretion and bacterial virulence, and thus likely function as structural components of the apparatus; two (VasH and VCA0122) are regulators that are required for T6SS gene expression and virulence; another two, VCA0121 and valine-glycine repeat protein G 3 (VgrG-3), are not essential for Hcp expression, secretion or bacterial virulence, and their functions are unknown; the last group is represented by VCA0118, which is not required for Hcp expression or secretion but still plays a role in both amoebae and bacterial killing and may therefore be an effector protein. We also showed that the clpV gene product is required for Dictyostelium virulence but is less important for killing E. coli. In addition, one vgrG gene (vgrG-2) outside of the T6SS gene cluster was required for bacterial killing but another (vgrG-1) was not. However, a bacterial killing defect was observed when vgrG-1 and vgrG-3 were both deleted. Several genes encoded in the same putative operon as vgrG-1 and vgrG-2 also contribute to virulence toward Dictyostelium but have a smaller effect on bacterial killing. Our results provide new insights into the functional requirements of V. cholerae's T6SS in the context of secretion as well as killing of bacterial and eukaryotic phagocytic cells