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Sreegowrinadh Javvadi, Sheo Shankar Pandey, Amita Mishra, Binod Bihari Pradhan, Subhadeep Chatterjee
Cellular iron homeostasis is critical for survival and growth. Bacteria employ a variety of strategies to sequester iron from the environment and to store intracellular iron surplus that can be utilized in iron-restricted conditions while also limiting the potential for the production of iron-induced reactive oxygen species (ROS). Here, we report that membrane-derived oligosaccharide (mdo) glucan, an intrinsic component of Gram-negative bacteria, sequesters the ferrous form of iron. Iron-binding, uptake, and localization experiments indicated that both secreted and periplasmic β-(1,2)-glucans bind iron specifically and promote growth under iron-restricted conditions...
December 8, 2017: EMBO Reports
Ki Woo Kim
Prokaryotic microbes possess a variety of appendages on their cell surfaces. The most commonly known surface appendages of bacteria include flagella, pili, curli, and spinae. Although archaea have archaella (archaeal flagella) and various types of pili that resemble those in bacteria, cannulae, and hami are unique to archaea. Typically involved in cell motility, flagella, the thickest appendages, are 20-26 nm and 10-14 nm wide in bacteria and archaea, respectively. Bacterial and archaeal pili are distinguished by their thin, short, hair-like structures...
December 2017: Journal of Microbiology / the Microbiological Society of Korea
Giulia Tamburrino, Salomé Llabrés, Owen N Vickery, Samantha J Pitt, Ulrich Zachariae
Widespread antibiotic resistance, especially of Gram-negative bacteria, has become a severe concern for human health. Tripartite efflux pumps are one of the major contributors to resistance in Gram-negative pathogens, by efficiently expelling a broad spectrum of antibiotics from the organism. In Neisseria gonorrhoeae, one of the first bacteria for which pan-resistance has been reported, the most expressed efflux complex is MtrCDE. Here we present the electrophysiological characterisation of the outer membrane component MtrE and the membrane fusion protein MtrC, obtained by a combination of planar lipid bilayer recordings and in silico techniques...
December 6, 2017: Scientific Reports
Fereshteh Heidari Tajabadi, Arturo Medrano-Soto, Masoud Ahmadzadeh, Gholamreza Salehi Jouzani, Milton H Saier
Bdellovibrio, δ-proteobacteria, including B. bacteriovorus (Bba) and B. exovorus (Bex), are obligate predators of other Gram-negative bacteria. While Bba grows in the periplasm of the prey cell, Bex grows externally. We have analyzed and compared the transport proteins of these 2 organisms based on the current contents of the Transporter Classification Database (TCDB; Bba has 103 transporters more than Bex, 50% more secondary carriers, and 3 times as many MFS carriers. Bba has far more metabolite transporters than Bex as expected from its larger genome, but there are 2 times more carbohydrate uptake and drug efflux systems, and 3 times more lipid transporters...
December 7, 2017: Journal of Molecular Microbiology and Biotechnology
Michael T Ringel, Gerald Draeger, Thomas Brüser
Pyoverdines are important siderophores that guarantee iron supply to important pathogenic and non-pathogenic pseudomonads in host habitats. A key characteristic of all pyoverdines is the fluorescent dihydroxyquinoline group that contributes two ligands to the iron complexes. Pyoverdines are derived from the non-ribosomally synthesized peptide ferribactin and their fluorophore is generated by periplasmic oxidation and cyclization reactions of D-tyrosine and L-diaminobutyric acid. The formation of the fluorophore is known to be driven by the periplasmic tyrosinase PvdP...
December 5, 2017: Journal of Biological Chemistry
Tifany Oulavallickal, Jodi L Brewster, James L O McKellar, Michael J Fairhurst, Nicholas A Tenci, Monica L Gerth
Nitrate- and nitrite-sensing (NIT) domains are found associated with a wide variety of bacterial receptors, including chemoreceptors. However, the structure of a chemoreceptor-associated NIT domain has not yet been characterized. Recently, a chemoreceptor named PscF was identified from the plant pathogen Pseudomonas syringae pv. actinidiae that is predicted to contain a periplasmic NIT domain. The PscF sensor domain (PscF-SD; residues 42-332) was cloned into an appropriate expression vector, recombinantly produced in Escherichia coli BL21-Gold(DE3) cells and purified via immobilized metal-affinity and size-exclusion chromatography...
December 1, 2017: Acta Crystallographica. Section F, Structural Biology Communications
C W Liew, R M Hynson, L A Ganuelas, N Shah-Mohammadi, A P Duff, S Kojima, M Homma, L K Lee
The bacterial flagellar motor drives the rotation of helical flagellar filaments to propel bacteria through viscous media. It consists of a dynamic population of mechanosensitive stators that are embedded in the inner membrane and activate in response to external load. This entails assembly around the rotor, anchoring to the peptidoglycan layer to counteract torque from the rotor and opening of a cation channel to facilitate an influx of cations, which is converted into mechanical rotation. Stator complexes are comprised of four copies of an integral membrane A subunit and two copies of a B subunit...
November 29, 2017: Biochemical and Biophysical Research Communications
Wei-Lin Hsu, Tadaomi Furuta, Minoru Sakurai
The Escherichia coli maltose transporter MalFGK2 -E belongs to the protein superfamily of ATP-binding cassette (ABC) transporters. This protein is composed of heterodimeric transmembrane domains (TMDs) MalF and MalG, and the homodimeric nucleotide-binding domains (NBDs) MalK2 . In addition to the TMDs and NBDs, the periplasmic maltose binding protein MalE captures maltose and shuttle it to the transporter. In this study, we performed all-atom molecular dynamics (MD) simulations on the maltose transporter and found that both the binding of MalE to the periplasmic side of the TMDs and binding of ATP to the MalK2 are necessary to facilitate the conformational change from the inward-facing state to the occluded state, in which MalK2 is completely dimerized...
December 1, 2017: Proteins
Małgorzata Marczak, Andrzej Mazur, Piotr Koper, Kamil Żebracki, Anna Skorupska
Rhizobia dwell and multiply in the soil and represent a unique group of bacteria able to enter into a symbiotic interaction with plants from the Fabaceae family and fix atmospheric nitrogen inside de novo created plant organs, called nodules. One of the key determinants of the successful interaction between these bacteria and plants are exopolysaccharides, which represent species-specific homo- and heteropolymers of different carbohydrate units frequently decorated by non-carbohydrate substituents. Exopolysaccharides are typically built from repeat units assembled by the Wzx/Wzy-dependent pathway, where individual subunits are synthesized in conjunction with the lipid anchor undecaprenylphosphate (und-PP), due to the activity of glycosyltransferases...
December 1, 2017: Genes
Paulina Cortes-Hernandez, Lenin Domínguez-Ramírez
Periplasmic Binding Proteins (PBPs) trap nutrients for their internalization into bacteria by ABC transporters. Ligand binding triggers PBP closure by bringing its two domains together like a Venus flytrap. The atomic determinants that control PBP opening and closure for nutrient capture and release are not known, although it is proposed that opening and ligand release occur while in contact with the ABC transporter for concurrent substrate translocation. In this paper we evaluated the effect of the isomerization of a conserved proline, located near the binding site, on the propensity of PBPs to open and close...
2017: PloS One
Shiuh-Bin Fang, Ching-Jou Huang, Chih-Hung Huang, Ke-Chuan Wang, Nai-Wen Chang, Hung-Yin Pan, Hsu-Wei Fang, Ming-Te Huang, Ching-Kuo Chen
The speG gene has been reported to regulate polyamine metabolism in Escherichia coli and Shigella, but its role in Salmonella remains unknown. Our preliminary studies have revealed that speG widely affects the transcriptomes of infected in vitro M and Caco-2 cells and that it is required for the intracellular replication of Salmonella enterica serovar Typhimurium (S. Typhimurium) in HeLa cells. In this study, we demonstrated that speG plays a time-dependent and cell type-independent role in the intracellular replication of S...
2017: Frontiers in Microbiology
Supurna Dhar, Hansi Kumari, Deepak Balasubramanian, Kalai Mathee
The bacterial cell-wall that forms a protective layer over the inner membrane is called the murein sacculus - a tightly cross-linked peptidoglycan mesh unique to bacteria. Cell-wall synthesis and recycling are critical cellular processes essential for cell growth, elongation and division. Both de novo synthesis and recycling involve an array of enzymes across all cellular compartments, namely the outer membrane, periplasm, inner membrane and cytoplasm. Due to the exclusivity of peptidoglycan in the bacterial cell-wall, these players are the target of choice for many antibacterial agents...
November 29, 2017: Journal of Medical Microbiology
Yong Cao, Bethany Griffith, Prasanna Bhomkar, David S Wishart, Mark T McDermott
The development of sensing systems for the measurement of small molecules is an active area of research. A sensor based approach for the measurement of metabolites can potentially provide the simplicity and portability required for widespread use. Rapid detection and quantitation of small-molecule metabolites can potentially emerge as an effective way to link the metabolite profile to the disease state. Surface plasmon resonance (SPR) combined with molecular recognition elements to deliver high specificity is a sensing platform that has been widely applied for a large range of biomolecules...
November 29, 2017: Analyst
Cesar A López, Timothy Travers, Klaas M Pos, Helen I Zgurskaya, S Gnanakaran
Antibiotic efflux is one of the most critical mechanisms leading to bacterial multidrug resistance. Antibiotics are effluxed out of the bacterial cell by a tripartite efflux pump, a complex machinery comprised of outer membrane, periplasmic adaptor, and inner membrane protein components. Understanding the mechanism of efflux pump assembly and its dynamics could facilitate discovery of novel approaches to counteract antibiotic resistance in bacteria. We built here an intact atomistic model of the Pseudomonas aeruginosa MexAB-OprM pump in a Gram-negative membrane model that contained both inner and outer membranes separated by a periplasmic space...
November 28, 2017: Scientific Reports
Jing Yuan, Fan Jin, Timo Glatter, Victor Sourjik
The PhoQ/PhoP two-component system plays an essential role in the response of enterobacteria to the environment of their mammalian hosts. It is known to sense several stimuli that are potentially associated with the host, including extracellular magnesium limitation, low pH, and the presence of cationic antimicrobial peptides. Here, we show that the PhoQ/PhoP two-component systems of Escherichia coli and Salmonella can also perceive an osmotic upshift, another key stimulus to which bacteria become exposed within the host...
November 28, 2017: Proceedings of the National Academy of Sciences of the United States of America
Jun Yop An, Humayun Sharif, Gil Bu Kang, Kyung Jin Park, Jung-Gyu Lee, Sukyeong Lee, Mi Sun Jin, Ji-Joon Song, Jimin Wang, Soo Hyun Eom
Prompt removal of misfolded membrane proteins and misassembled membrane protein complexes is essential for membrane homeostasis. However, the elimination of these toxic proteins from the hydrophobic membrane environment has high energetic barriers. The transmembrane protein, FtsH, is the only known ATP-dependent protease responsible for this task. The mechanisms by which FtsH recognizes, unfolds, translocates, and proteolyzes its substrates remain unclear. The structure and function of the ATPase and protease domains of FtsH have been previously characterized while the role of the FtsH periplasmic domain has not clearly identified...
November 24, 2017: Biochemical and Biophysical Research Communications
Paulo V S Dias, Fernanda S Arthuso, João E Oliveira, Miriam F Suzuki, José M Sousa, Maria Teresa C P Ribela, Paolo Bartolini, Carlos R J Soares
Reversed-phase high-performance liquid chromatography (RP-HPLC) has been used to analyze Interferon α-2 (IFN-α2) as a pure protein or as a pharmaceutical preparation: a method for analyzing periplasmic IFN-α2 directly in osmotic shock extract has, however, never been reported. This work describes an RP-HPLC methodology for the qualitative and quantitative analysis of human IFN-α2a and IFN-α2b directly in bacterial periplasmic extracts or in purified preparations. The analytical method has been set up and validated for accuracy, precision, linearity, sensitivity and specificity...
November 21, 2017: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
Mark K Haynes, Matthew Garcia, Ryan Peters, Anna Waller, Pietro Tedesco, Oleg Ursu, Cristian G Bologa, Radleigh G Santos, Clemencia Pinilla, Terry H Wu, Julie A Lovchik, Tudor I Oprea, Larry A Sklar, George P Tegos
The resistance nodulation cell division (RND) family of proteins are inner membrane transporters that associate with periplasmic adaptor proteins and outer membrane porins to affect substrate transport from the cytosol and periplasm in Gram-negative bacteria. Various structurally diverse compounds are substrates of RND transporters. Along with their notable role in antibiotic resistance, these transporters are essential for niche colonization, quorum sensing, and virulence as well as for the removal of fatty acids and bile salts...
2018: Methods in Molecular Biology
Hiroshi Nikaido
Transporters undergo large conformational changes in their functional cycle. RND (Resistance-Nodulation-Division) family efflux transporters usually exist as homotrimers, and each protomer was proposed to undergo a cycle of conformational changes in succession so that at any given time the trimer would contain three protomers of different conformations, the functionally rotating mechanism of transport. This mechanism implies that the inactivation of one protomer among three will inactivate the entire trimeric ensemble by blocking the functional rotation...
2018: Methods in Molecular Biology
Mohan Babu, Cedoljub Bundalovic-Torma, Charles Calmettes, Sadhna Phanse, Qingzhou Zhang, Yue Jiang, Zoran Minic, Sunyoung Kim, Jitender Mehla, Alla Gagarinova, Irina Rodionova, Ashwani Kumar, Hongbo Guo, Olga Kagan, Oxana Pogoutse, Hiroyuki Aoki, Viktor Deineko, J Harry Caufield, Erik Holtzapple, Zhongge Zhang, Ake Vastermark, Yogee Pandya, Christine Chieh-Lin Lai, Majida El Bakkouri, Yogesh Hooda, Megha Shah, Dan Burnside, Mohsen Hooshyar, James Vlasblom, Sessandra V Rajagopala, Ashkan Golshani, Stefan Wuchty, Jack F Greenblatt, Milton Saier, Peter Uetz, Trevor F Moraes, John Parkinson, Andrew Emili
Bacterial cell envelope protein (CEP) complexes mediate a range of processes, including membrane assembly, antibiotic resistance and metabolic coordination. However, only limited characterization of relevant macromolecules has been reported to date. Here we present a proteomic survey of 1,347 CEPs encompassing 90% inner- and outer-membrane and periplasmic proteins of Escherichia coli. After extraction with non-denaturing detergents, we affinity-purified 785 endogenously tagged CEPs and identified stably associated polypeptides by precision mass spectrometry...
November 27, 2017: Nature Biotechnology
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