The Structure and Interactions of Periplasmic Domains of Crucial MmpL Membrane Proteins from Mycobacterium tuberculosis

SummaryMycobacterium tuberculosis mycobacterial membrane protein large (MmpL) proteins are important in substrate transport across the inner membrane. Here, we show that MmpL proteins are classified into two phylogenetic clusters, where MmpL cluster II contains three soluble domains (D1, D2, and D3) and has two full-length members, MmpL3 and MmpL11. Significantly, MmpL3 is currently the most druggable M. tuberculosis target. We have solved the 2.4-Å MmpL11-D2 crystal structure, revealing structural homology to periplasmic porter subdomains of RND (multidrug) transporters. The resulting predicted cluster II MmpL membrane topology has D1 and D2 residing, and possibly interacting, within the periplasm. Crosslinking and biolayer interferometry experiments confirm that cluster II D1 and D2 bind with weak affinities, and guided D1-D2 heterodimeric model assemblies. The predicted full-length MmpL3 and MmpL11 structural models reveal key substrate binding and transport residues, and may serve as templates to set the stage for in silico anti-tuberculosis drug development

The structure and interactions of periplasmic domains of crucial MmpL membrane proteins from Mycobacterium tuberculosis

SummaryMycobacterium tuberculosis M ycobacterial membrane protein Large (MmpL) proteins are important in substrate transport across the inner membrane. Herein, we show that MmpL proteins are classified into two phylogenetic clusters, where MmpL Cluster II contains three soluble domains (D1, D2, and D3) and has two full-length members, MmpL3 and MmpL11. Significantly, MmpL3 is currently the most druggable M. tuberculosis target. We have solved the 2.4 Å MmpL11-D2 crystal structure revealing structural homology to periplasmic porter subdomains of RND (multidrug) transporters. The resulting predicted Cluster II MmpL membrane topology has D1 and D2 residing, and possibly interacting, within the periplasm. Crosslinking and biolayer interferometry experiments confirm that Cluster II D1 and D2 bind with weak affinities, and guided D1-D2 heterodimeric model assemblies. The predicted full-length MmpL3 and MmpL11 structural models reveal key substrate binding and transport residues, and may serve as templates to set the stage for in silico anti-tuberculosis drug development.Graphical abstrac

Combined Phosphoproteomics and Bioinformatics Strategy in Deciphering Drug Resistant Related Pathways in Triple Negative Breast Cancer

Because of the absence of a clear therapeutic target for triple negative breast cancer (TNBC), conventional chemotherapy is the only available systemic treatment option for these patients. Despite chemotherapy treatment, TNBC patients still have worse prognosis when compared with other breast cancer patients. The study is to investigate unique phosphorylated proteins expressed in chemoresistant TNBC cell lines. In the current study, twelve TNBC cell lines were subjected to drug sensitivity assays against chemotherapy drugs docetaxel, doxorubicin, gemcitabine, and cisplatin. Based on their half maximal inhibitory concentrations, four resistant and two sensitive cell lines were selected for further analysis. The phosphopeptides from these cells were enriched with TiO2 beads and fractionated using strong cation exchange. 1,645 phosphoprotein groups and 9,585 unique phosphopeptides were identified by a high throughput LC-MS/MS system LTQ-Orbitrap. The phosphopeptides were further filtered with Ascore system and 1,340 phosphoprotein groups, 2,760 unique phosphopeptides, and 4,549 unique phosphosites were identified. Our study suggested that differentially phosphorylated Cdk5, PML, AP-1, and HSF-1 might work together to promote vimentin induced epithelial to mesenchymal transition (EMT) in the drug resistant cells. EGFR and HGF were also shown to be involved in this process

Work–Family Interface and Crossover Effects: Exploring for the Effects of Gender

Despite mixed and sometimes confusing results posed by the role of gender in the work-family (W-F) interface, gender research in WF studies cannot be laid to rest. In this chapter we review W-F spillover and crossover literature involving dual earner couples in different cultural contexts – Anglo/European, Asian and Middle Eastern – to identify gendered patterns in spillover and crossover effects experienced by men (husbands) and women (wives). Gender asymmetry continues to be evident in dyadic couple relationships across cultures, especially when one considers crossover effects