Outer membrane vesicles (OMVs) (∼50-250 nm in diameter) are produced by both pathogenic and nonpathogenic bacteria as a canonical end product of secretion. In this review, we focus on the OMVs produced by gram-negative bacteria. We provide an overview of the OMV structure, various factors regulating their production, and their role in modulating host immune response using a few representative examples. In light of the importance of the diverse cargoes carried by OMVs, we discuss the different modes of their entry into the host cell and advances in the high-throughput detection of these OMVs. A conspicuous application of OMVs lies in the field of vaccination; we discuss its success in immunization against human diseases such as pertussis, meningitis, shigellosis and aqua-farming endangering diseases like edwardsiellosis.

p66Shc, a member of the ShcA (Src homologous- collagen homologue) adaptor protein family, is one of the three isoforms of this family along with p46Shc and p52Shc. p66Shc, a 66 kDa protein is different from the other isoforms of the ShcA family. p66Shc is the longest isoform of the ShcA family. p66Shc has an additional CH domain at the N-terminal, called the CH2 domain, which is not not present in the other isoforms. This CH2 domain contains a very crucial S36 residue which is phosphorylated in response to oxidative stress and plays a role in apoptosis. Whereas p52Shc and p46Shc are ubiquitously expressed, p66Shc shows constrained expression. This adaptor protein has been shown to be involved in mediating and executing the post effects of oxidative stress and increasing body of evidence is pinpointing to its role in carcinogenesis as well. It shows proto-oncogenic as well as pro-apoptotic properties. This multitasking protein is involved in regulating different networks of cell signaling. On one hand it shows an increased expression profile in different cancers, has a positive role in cell proliferation and migration, whereas on the other hand it promotes apoptosis under oxidative stress conditions by acting as a sensor of ROS (Reactive Oxygen Species). This paradoxical role of p66Shc could be attributed to its involvement in ROS production, as ROS is known to both induce cell proliferation as well as apoptosis. p66Shc by regulating intracellular ROS levels plays a crucial role in regulating longevity and cell senescence. These multi-faceted properties of p66Shc make it a perfect candidate protein for further studies in various cancers and aging related diseases. p66Shc can be targeted in terms of it being used as a possible therapeutic target in various diseases. This review focuses on p66Shc and highlights its role in promoting apoptosis via different cell signaling networks, its role in cell proliferation, along with its presence and role in different forms of cancers.

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The high interfacial activity of protein-polymer conjugates has inspired their use as stabilizers for Pickering emulsions, resulting in many interesting applications such as synthesis of templated micro-compartments and protocells or vehicles for drug and gene delivery. In this study we report, for the first time, the stabilization of Pickering emulsions with conjugates of a genetically modified transmembrane protein, ferric hydroxamate uptake protein component A (FhuA). The lysine residues of FhuA with open pore (FhuA ΔCVF) were modified to attach an initiator and consequently controlled radical polymerization (CRP) carried out via the grafting-from technique. The resulting conjugates of FhuA ΔCVF with poly(N-isopropylacrylamide) (PNIPAAm) and poly((2-dimethylamino)ethyl methacrylate) (PDMAEMA), the so-called building blocks based on transmembrane proteins (BBTP), have been shown to engender larger structures. The properties such as pH-responsivity, temperature-responsivity and interfacial activity of the BBTP were analyzed using UV-Vis spectrophotometry and pendant drop tensiometry. The BBTP were then utilized for the synthesis of highly stable Pickering emulsions, which could remain non-coalesced for well over a month. A new UV-crosslinkable monomer was synthesized and copolymerized with NIPAAm from the protein. The emulsion droplets, upon crosslinking of polymer chains, yielded micro-compartments. Fluorescence microscopy proved that these compartments are of micrometer scale, while cryo-scanning electron microscopy and scanning force microscopy analysis yielded a thickness in the range of 11.1 ± 0.6 to 38.0 ± 18.2 nm for the stabilizing layer of the conjugates. Such micro-compartments would prove to be beneficial in drug delivery applications, owing to the possibility of using the channel of the transmembrane protein as a gate and the smart polymer chains as trigger switches to tune the behavior of the capsules.

The ultrastructural functions of the electron-dense glycopeptidolipid-containing outermost layer (OL), the arabinogalactanmycolic acid-containing electron-transparent layer (ETL), and the electron-dense peptidoglycan layer (PGL) of the mycobacterial cell wall in septal growth and constriction are not clear. Therefore, using transmission electron microscopy, we studied the participation of the three layers in septal growth and constriction in the fast-growing saprophytic species Mycobacterium smegmatis and the slow-growing pathogenic species Mycobacterium xenopi and Mycobacterium tuberculosis in order to document the processes in a comprehensive and comparative manner and to find out whether the processes are conserved across different mycobacterial species. A complete septal partition is formed first by the fresh synthesis of the septal PGL (S-PGL) and septal ETL (S-ETL) from the envelope PGL (E-PGL) in M. smegmatis and M. xenopi. The S-ETL is not continuous with the envelope ETL (E-ETL) due to the presence of the E-PGL between them. The E-PGL disappears, and the S-ETL becomes continuous with the E-ETL, when the OL begins to grow and invaginate into the S-ETL for constriction. However, in M. tuberculosis, the S-PGL and S-ETL grow from the E-PGL and E-ETL, respectively, without a separation between the E-ETL and S-ETL by the E-PGL, in contrast to the process in M. smegmatis and M. xenopi. Subsequent growth and invagination of the OL into the S-ETL of the septal partition initiates and completes septal constriction in M. tuberculosis. A model for the conserved sequential process of mycobacterial septation, in which the formation of a complete septal partition is followed by constriction, is presented. The probable physiological significance of the process is discussed. The ultrastructural features of septation and constriction in mycobacteria are unusually different from those in the well-studied organisms Escherichia coli and Bacillus subtilis.T he presence of a bilayered plasma membrane and a triplelayered cell wall, constituted by an electron-dense outermost layer (OL) containing mostly glycopeptidolipids (11, 37), an electron-transparent layer (ETL) below, consisting of an arabinogalactan-mycolic acid complex (22,36), and an electrondense peptidoglycan layer (PGL), has been observed and characterized through ultrastructural and biochemical studies in Mycobacterium smegmatis (7,12,16,27), Mycobacterium xenopi and other mycobacterial species (reviewed in references 2, 17, 24, and 27), Mycobacterium tuberculosis (3, 9, 33; reviewed in reference 5), Mycobacterium leprae (33), and Mycobacterium kansasii (25,27). Numerous studies had been carried out on the ultrastructures of the OL, ETL, and PGL, their molecular compositions, and the probable roles of these layers in the physiology, pathology, and virulence of different mycobacterial species (6-8; reviewed in references 3 and 5). However, the functional roles of these layers in cell division remained unclear. Studies on mycobacterial cell division (reviewed in refe...

Glucose-methanol-choline (GMC) oxidoreductases are a large and diverse family of flavin-binding enzymes found in all kingdoms of life. Recently, a new related family of proteins has been discovered in algae named fatty acid photodecarboxylases (FAPs). These enzymes use the energy of light to convert fatty acids to the corresponding Cn-1 alkanes or alkenes, and hold great potential for biotechnological application. In this work, we aimed at uncovering the natural diversity of FAPs and their relations with other GMC oxidoreductases. We reviewed the available GMC structures, assembled a large dataset of GMC sequences, and found that one active site amino acid, a histidine, is extremely well conserved among the GMC proteins but not among FAPs, where it is replaced with alanine. Using this criterion, we found several new potential FAP genes, both in genomic and metagenomic databases, and showed that related bacterial, archaeal and fungal genes are unlikely to be FAPs. We also identified several uncharacterized clusters of GMC-like proteins as well as subfamilies of proteins that lack the conserved histidine but are not FAPs. Finally, the analysis of the collected dataset of potential photodecarboxylase sequences revealed the key active site residues that are strictly conserved, whereas other residues in the vicinity of the flavin adenine dinucleotide (FAD) cofactor and in the fatty acid-binding pocket are more variable. The identified variants may have different FAP activity and selectivity and consequently may prove useful for new biotechnological applications, thereby fostering the transition from a fossil carbon-based economy to a bio-economy by enabling the sustainable production of hydrocarbon fuels.

Development of a novel whole cell system for chiral separation of arginine enantiomers through an engineered outer membrane channel protein ferric hydroxamate uptake protein A (FhuA).

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