The use of bicistronic vectors, which contain two target genes under one promoter, has been the most common practice for the heterologous production of binary protein complexes. The major problem of this method is the much lower expression of the second gene compared with that of the first gene next to the promoter. We tested a simple idea of whether inclusion of an additional promoter in front of the second gene may remove the problem. Compared with bicistronic vectors, corresponding two-promoter vectors yielded four to nine times larger amounts of the complexes between BCL-2 family proteins, BCL-X L :BAD, BCL-X L :BIM-S, and CED-9:EGL-1 in bacterial cells as a result of significantly increased expression of the second genes in a manner independent of the order of the target genes. With the two-promoter system, we produced two other complexes in large quantity suitable for extensive crystallization trial. The method does not accompany any technical disadvantages, and represents a significant improvement from the conventional method, which should enjoy wide application for the coexpression of binary or higher order protein complexes by extension.

Transport protein particle (TRAPP) comprises a family of two highly related multiprotein complexes, with seven common subunits, that serve to target different classes of transport vesicles to their appropriate compartments. Defining the architecture of the complexes will advance our understanding of the functional differences between these highly related molecular machines. Genetic analyses in yeast suggested a specific interaction between the TRAPP subunits Bet3p and Trs33p. A mammalian bet3-trs33 complex was crystallized, and the structure was solved to 2.2 Å resolution. Intriguingly, the overall fold of the bet3 and trs33 monomers was similar, although the proteins had little overall sequence identity. In vitro experiments using yeast TRAPP subunits indicated that Bet3p binding to Trs33p facilitates the interaction between Bet3p and another TRAPP subunit, Bet5p. Mutational analysis suggests that yeast Trs33p facilitates other Bet3p protein-protein interactions. Furthermore, we show that Trs33p can increase the Golgi-localized pool of a mutated Bet3 protein normally found in the cytosol. We propose that one of the roles of Trs33p is to facilitate the incorporation of the Bet3p subunit into assembling TRAPP complexes.

Purpose: Both atopy and bronchial hyperresponsiveness (BHR) are characteristic features of asthma. Several BHR studies comparing groups of atopic and nonatopic asthmatics have reported conflicting results. The aim of this study was to compare BHR to indirect stimuli, such as mannitol or exercise, between atopic and nonatopic asthmatics in children Methods: We performed a retrospective analysis of data from 110 children with asthma, aged 6-18 years using skin prick tests, and serum total and specific IgE levels. Atopy degree was measured using the sum of graded wheal size or the sum of the allergen-specific IgE. Bronchial provocation tests (BPTs) using methacholine were performed on all subjects. BPTs using indirect simuli, including exercise and mannitol, were also performed. Results: Asthma cases were classified as atopic asthma (n= 83) or nonatopic asthma (n= 27) from skin prick or allergen-specific IgE test results. There was no significant difference in the prevalence of BHR to mannitol or exercise between atopic and nonatopic asthmatics. Atopic asthma had a significantly lower postexercise maximum decrease in % forced expiratory volume in 1 second (FEV1) (geometric mean [95% confidence interval]: 31.9 [22.9-40.9] vs. 14.0 [9.4-18.6], P = 0.015) and a methacholine PC20 (provocative concentration of methacholine inducing a 20% fall in FEV1) than nonatopic asthmatics (geometric mean [95% confidence interval]: 1.24 [0.60-1.87] ng/mL vs. 4.97 [3.47-6.47]) ng/mL, P= 0.001), whereas mannitol PD15 (cumulative provocative dose causing a 15% fall in FEV1) was not significantly different between the 2 groups. Conclusion: There was no significant difference in the prevalence of BHR to mannitol or exercise between atopic and nonatopic asthmatics in children. (Allergy Asthma Respir Dis 2017:5:83-91)