The membrane: transertion as an organizing principle in membrane heterogeneity

Matsumoto, Kouji; Hara, Hiroshi; Fishov, Itzhak; Mileykovskaya, Eugenia; Norris, Victor

doi:10.3389/fmicb.2015.00572

Cited by 56 publications

(52 citation statements)

References 247 publications

(399 reference statements)

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“…In E. coli, the RNA transcribed from the gsp operon has been mapped (44), and multiple translation initiation events (45) ensure that many molecules of GspD (and the other subunits of the T2SS) would be synthesized in close proximity, translocated into the periplasm in close proximity, and translocated to arrive at the same or a neighboring LolB receptor site within a short window of time (46)(47)(48)(49). Computer simulations and protein localization studies confirm that transertion creates local regions of high concentration for a given membrane protein (reviewed by Matsumoto et al [48]). In this scenario, the local concentration of GspD monomers in the outer membrane would be relatively high and would favor an allosteric activation of the monomers to polymerize.…”

Section: Discussionmentioning

confidence: 99%

Structure and Membrane Topography of the Vibrio-Type Secretin Complex from the Type 2 Secretion System of Enteropathogenic Escherichia coli

et al. 2018

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The ␤-barrel assembly machinery (BAM) complex is the core machinery for the assembly of ␤-barrel membrane proteins, and inhibition of BAM complex activity is lethal to bacteria. Discovery of integral membrane proteins that are key to pathogenesis and yet do not require assistance from the BAM complex raises the question of how these proteins assemble into bacterial outer membranes. Here, we address this question through a structural analysis of the type 2 secretion system (T2SS) secretin from enteropathogenic Escherichia coli O127:H6 strain E2348/69. Long ␤-strands assemble into a barrel extending 17 Å through and beyond the outer membrane, adding insight to how these extensive ␤-strands are assembled into the E. coli outer membrane. The substrate docking chamber of this secretin is shown to be sufficient to accommodate the substrate mucinase SteC.IMPORTANCE In order to cause disease, bacterial pathogens inhibit immune responses and induce pathology that will favor their replication and dissemination. In Gram-negative bacteria, these key attributes of pathogenesis depend on structures assembled into or onto the outer membrane. One of these is the T2SS. The Vibriotype T2SS mediates cholera toxin secretion in Vibrio cholerae, and in Escherichia coli O127:H6 strain E2348/69, the same machinery mediates secretion of the mucinases that enable the pathogen to penetrate intestinal mucus and thereby establish deadly infections.KEYWORDS protein secretion, bacterial pathogenesis, BAM complex, transertion, outer membrane, lipoproteins, secretin E nteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) are pathogens causing diseases that range from diarrhea to hemorrhagic colitis and hemolytic-uremic syndrome in humans. In order to access the epithelial layer of the human gut, these pathogens secrete mucinases that cause a thinning of the mucus layer to accelerate pathogenesis (1-3). These large mucinases are folded into functionally active forms in the bacterial periplasm before being secreted across the outer membrane (1,(4)(5)(6)(7)(8). Secretion of these mucinases is mediated by the type 2 secretion system (T2SS), with a defining component of the T2SS being the secretin: an approximately 70-kDa protein that homo-oligomerizes to form an ϳ1-MDa secretin complex (9). The secretin complex is embedded in the outer membrane and spans the periplasm (10). Diversity in the sequence features of secretins led to the classification of two major forms of the T2SS: (i) the Klebsiella type, represented in a broad and diverse set of bacterial species and which has been functionally characterized best in Klebsiella oxytoca (11), and (ii) the Vibrio type, which is found only in a few species of Vibrio and pathovars of Escherichia coli, including EPEC and EHEC (7). Other secretins, including those from the T2SS expressed by species of Pseudomonas, Legionella, and Acinetobacter, are so diverse in sequence that their relationships have remained complex and

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Section: Discussionmentioning

confidence: 99%

Structure and Membrane Topography of the Vibrio-Type Secretin Complex from the Type 2 Secretion System of Enteropathogenic Escherichia coli

et al. 2018

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“…Interestingly, my research group later contributed to the body of evidence supporting lipid domains with specifically associated proteins in bacterial membranes (reviewed in Ref. 5).…”

Section: In the Beginningmentioning

confidence: 99%

Understanding phospholipid function: Why are there so many lipids?

Dowhan¹

2017

Journal of Biological Chemistry

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In the 1970s, phospholipids were still considered mere building blocks of the membrane lipid bilayer, but the subsequent realization that phospholipids could also serve as second messengers brought new interest to the field. My own passion for the unique amphipathic properties of lipids led me to seek other, non-signaling functions for phospholipids, particularly in their interactions with membrane proteins. This seemed to be the last frontier in protein chemistry and enzymology to be conquered. I was fortunate to find my way to Eugene Kennedy's laboratory, where both membrane proteins and phospholipids were the foci of study, thus providing a jumping-off point for advancing our fundamental understanding of lipid synthesis, membrane protein biosynthesis, phospholipid and membrane protein trafficking, and the cellular roles of phospholipids. After purifying and characterizing enzymes of phospholipid biosynthesis in Escherichia coli and cloning of several of the genes encoding these enzymes in E. coli and Saccharomyces cerevisiae, I was in a position to alter phospholipid composition in a systematic manner during the cell cycle in these microorganisms. My group was able to establish, contrary to common assumption (derived from the fact that membrane proteins retain activity in detergent extracts) that phospholipid environment is a strong determining factor in the function of membrane proteins. We showed that molecular genetic alterations in membrane lipid composition result in many phenotypes, and uncovered direct lipid-protein interactions that govern dynamic structural and functional properties of membrane proteins. Here I present my personal "reflections" on how our understanding of phospholipid functions has evolved.

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“…Transcription of many genes distributed throughout the genome might provide driving force for chromosome segregation, maintain appropriate chromosomal structure with supercoils separated by expressed regions, or reorganize the nucleoid within the cell (Kjos & Veening, 2014;Le et al, 2013;Stracy et al, 2015;Woldringh, 2002). Moreover, transertion (co-transcriptional translational and protein translocation) of membrane proteins might generate DNA movement resulting from competition of DNA-RNAP-mRNA-ribosome complexes for membrane surface (Matsumoto et al, 2015;Woldringh, 2002). However, to the best of our knowledge the involvement of RNA polymerase in the process of plasmid segregation has not been demonstrated so far.…”

Section: Discussionmentioning

confidence: 99%

Omega (ParB) binding sites together with the RNA polymerase-recognized sequence are essential for centromeric functions of the Pω region in the partition system of pSM19035

Dmowski

Kern-Zdanowicz

2016

Microbiology

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Partition systems contribute to stable plasmid inheritance in bacteria through the active separation of DNA molecules to daughter cells, and the centromeric sequence located either upstream or downstream of canonical partition operons plays an important role in this process. A specific DNAbinding protein binds to this sequence and interacts with the motor NTPase protein to form a nucleoprotein complex. The inc18-family plasmid pSM19035 is partitioned by products of d and ! genes, with d encoding a Walker-type ATPase and ! encoding a DNA-binding protein. As the two genes are transcribed separately, this system differs from others in its organization; nonetheless, expression of these genes is regulated by Omega, which also regulates the copy number of the plasmid (by controlling copS gene expression). Protein Omega specifically recognizes WATCACW heptad repeats. In this study, we constructed a synthetic d! operon to enable an analysis of the centromeric functions of Omega-binding sites P d , P ! and P copS , discrete from their promoter functions. Our results show that these three regions do not support plasmid stabilization equally. We demonstrate that the P ! site alone can simultaneously drive the expression of partition genes from the synthetic d! operon and act as a unique centromeric sequence to promote the most efficient plasmid partitioning. Moreover, P ! can support the centromeric function in concert with the synthetic d! operon expressed from a heterologous promoter demonstrating that P ! is the main centromeric sequence of the d-! partition system. Additionally, the RNA polymeraserecognized sequence in P ! is essential for its centromeric function.

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The membrane: transertion as an organizing principle in membrane heterogeneity

Cited by 56 publications

References 247 publications

Structure and Membrane Topography of the Vibrio-Type Secretin Complex from the Type 2 Secretion System of Enteropathogenic Escherichia coli

Structure and Membrane Topography of the Vibrio-Type Secretin Complex from the Type 2 Secretion System of Enteropathogenic Escherichia coli

Understanding phospholipid function: Why are there so many lipids?

Omega (ParB) binding sites together with the RNA polymerase-recognized sequence are essential for centromeric functions of the Pω region in the partition system of pSM19035

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