The Experts below are selected from a list of 68892 Experts worldwide ranked by ideXlab platform

Huizhang Shen - One of the best experts on this subject based on the ideXlab platform.

Xiaohong Shi - One of the best experts on this subject based on the ideXlab platform.

  • Bunyamwera orthobunyavirus glycoprotein precursor is processed by cellular Signal peptidase and Signal peptide peptidase
    Proceedings of the National Academy of Sciences of the United States of America, 2016
    Co-Authors: Xiaohong Shi, Catherine H. Botting, Mark Niglas, Benjamin Brennan, Sally L. Shirran, Agnieszka M. Szemiel
    Abstract:

    The M genome segment of Bunyamwera virus (BUNV)—the prototype of both the Bunyaviridae family and the Orthobunyavirus genus—encodes the glycoprotein precursor (GPC) that is proteolytically cleaved to yield two viral structural glycoproteins, Gn and Gc, and a nonstructural protein, NSm. The cleavage mechanism of orthobunyavirus GPCs and the host proteases involved have not been clarified. In this study, we investigated the processing of BUNV GPC and found that both NSm and Gc proteins were cleaved at their own Internal Signal peptides (SPs), in which NSm domain I functions as SPNSm and NSm domain V as SPGc. Moreover, the domain I was further processed by a host intramembrane-cleaving protease, Signal peptide peptidase, and is required for cell fusion activities. Meanwhile, the NSm domain V (SPGc) remains integral to NSm, rendering the NSm topology as a two-membrane-spanning integral membrane protein. We defined the cleavage sites and boundaries between the processed proteins as follows: Gn, from residue 17–312 or nearby residues; NSm, 332–477; and Gc, 478–1433. Our data clarified the mechanism of the precursor cleavage process, which is important for our understanding of viral glycoprotein biogenesis in the genus Orthobunyavirus and thus presents a useful target for intervention strategies.

  • requirement of the n terminal region of orthobunyavirus nonstructural protein nsm for virus assembly and morphogenesis
    Journal of Virology, 2006
    Co-Authors: Xiaohong Shi, Alain Kohl, Vincent H J Leonard, Angela Mclees, Richard M Elliott
    Abstract:

    The nonstructural protein NSm of Bunyamwera virus (BUNV), the prototype of the Bunyaviridae family, is encoded by the M segment in a polyprotein precursor, along with the virion glycoproteins, in the order Gn-NSm-Gc. As little is known of its function, we examined the intracellular localization, membrane integrality, and topology of NSm and its role in virus replication. We confirmed that NSm is an integral membrane protein and that it localizes in the Golgi complex, together with Gn and Gc. Coimmunoprecipitation assays and yeast two-hybrid analysis demonstrated that NSm was able to interact with other viral proteins. NSm is predicted to contain three hydrophobic (I, III, and V) and two nonhydrophobic (II and IV) domains. The N-terminal nonhydrophobic domain II was found in the lumen of an intracellular compartment. A novel BUNV assembly assay was developed to monitor the formation of infectious virus-like-particles (VLPs). Using this assay, we showed that deletions of either the complete NSm coding region or domains I, II, and V individually seriously compromised VLP production. Consistently, we were unable to rescue viable viruses by reverse genetics from cDNA constructs that contained the same deletions. However, we could generate mutant BUNV with deletions in NSm domains III and IV and also a recombinant virus with the green fluorescent protein open reading frame inserted into NSm domain IV. The mutant viruses displayed differences in their growth properties. Overall, our data showed that the N-terminal region of NSm, which includes domain I and part of domain II, is required for virus assembly and that the C-terminal hydrophobic domain V may function as an Internal Signal sequence for the Gc glycoprotein.

Reinhart A F Reithmeier - One of the best experts on this subject based on the ideXlab platform.

  • effect of the southeast asian ovalocytosis deletion on the conformational dynamics of Signal anchor transmembrane segment 1 of red cell anion exchanger 1 ae1 band 3 or slc4a1
    Biochemistry, 2017
    Co-Authors: Philip W Fowler, Mark S P Sansom, Reinhart A F Reithmeier
    Abstract:

    The first transmembrane (TM1) helix in the red cell anion exchanger (AE1, Band 3, or SLC4A1) acts as an Internal Signal anchor that binds the Signal recognition particle and directs the nascent polypeptide chain to the endoplasmic reticulum (ER) membrane where it moves from the translocon laterally into the lipid bilayer. The sequence N-terminal to TM1 forms an amphipathic helix that lies at the membrane interface and is connected to TM1 by a bend at Pro403. Southeast Asian ovalocytosis (SAO) is a red cell abnormality caused by a nine-amino acid deletion (Ala400–Ala408) at the N-terminus of TM1. Here we demonstrate, by extensive (∼4.5 μs) molecular dynamics simulations of TM1 in a model 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine membrane, that the isolated TM1 peptide is highly dynamic and samples the structure of TM1 seen in the crystal structure of the membrane domain of AE1. The SAO deletion not only removes the proline-induced bend but also causes a “pulling in” of the part of the amphipathic he...

  • Effect of the Southeast Asian Ovalocytosis Deletion on the Conformational Dynamics of Signal-Anchor Transmembrane Segment 1 of Red Cell Anion Exchanger 1 (AE1, Band 3, or SLC4A1)
    2017
    Co-Authors: Philip W Fowler, Mark S P Sansom, Reinhart A F Reithmeier
    Abstract:

    The first transmembrane (TM1) helix in the red cell anion exchanger (AE1, Band 3, or SLC4A1) acts as an Internal Signal anchor that binds the Signal recognition particle and directs the nascent polypeptide chain to the endoplasmic reticulum (ER) membrane where it moves from the translocon laterally into the lipid bilayer. The sequence N-terminal to TM1 forms an amphipathic helix that lies at the membrane interface and is connected to TM1 by a bend at Pro403. Southeast Asian ovalocytosis (SAO) is a red cell abnormality caused by a nine-amino acid deletion (Ala400–Ala408) at the N-terminus of TM1. Here we demonstrate, by extensive (∼4.5 μs) molecular dynamics simulations of TM1 in a model 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine membrane, that the isolated TM1 peptide is highly dynamic and samples the structure of TM1 seen in the crystal structure of the membrane domain of AE1. The SAO deletion not only removes the proline-induced bend but also causes a “pulling in” of the part of the amphipathic helix into the hydrophobic phase of the bilayer, as well as the C-terminal of the peptide. The dynamics of the SAO peptide very infrequently resembles the structure of TM1 in AE1, demonstrating the disruptive effect the SAO deletion has on AE1 folding. These results provide a precise molecular view of the disposition and dynamics of wild-type and SAO TM1 in a lipid bilayer, an important early biosynthetic intermediate in the insertion of AE1 into the ER membrane, and extend earlier results of cell-free translation experiments

Agnieszka M. Szemiel - One of the best experts on this subject based on the ideXlab platform.

  • Bunyamwera orthobunyavirus glycoprotein precursor is processed by cellular Signal peptidase and Signal peptide peptidase
    Proceedings of the National Academy of Sciences of the United States of America, 2016
    Co-Authors: Xiaohong Shi, Catherine H. Botting, Mark Niglas, Benjamin Brennan, Sally L. Shirran, Agnieszka M. Szemiel
    Abstract:

    The M genome segment of Bunyamwera virus (BUNV)—the prototype of both the Bunyaviridae family and the Orthobunyavirus genus—encodes the glycoprotein precursor (GPC) that is proteolytically cleaved to yield two viral structural glycoproteins, Gn and Gc, and a nonstructural protein, NSm. The cleavage mechanism of orthobunyavirus GPCs and the host proteases involved have not been clarified. In this study, we investigated the processing of BUNV GPC and found that both NSm and Gc proteins were cleaved at their own Internal Signal peptides (SPs), in which NSm domain I functions as SPNSm and NSm domain V as SPGc. Moreover, the domain I was further processed by a host intramembrane-cleaving protease, Signal peptide peptidase, and is required for cell fusion activities. Meanwhile, the NSm domain V (SPGc) remains integral to NSm, rendering the NSm topology as a two-membrane-spanning integral membrane protein. We defined the cleavage sites and boundaries between the processed proteins as follows: Gn, from residue 17–312 or nearby residues; NSm, 332–477; and Gc, 478–1433. Our data clarified the mechanism of the precursor cleavage process, which is important for our understanding of viral glycoprotein biogenesis in the genus Orthobunyavirus and thus presents a useful target for intervention strategies.

Philip W Fowler - One of the best experts on this subject based on the ideXlab platform.

  • effect of the southeast asian ovalocytosis deletion on the conformational dynamics of Signal anchor transmembrane segment 1 of red cell anion exchanger 1 ae1 band 3 or slc4a1
    Biochemistry, 2017
    Co-Authors: Philip W Fowler, Mark S P Sansom, Reinhart A F Reithmeier
    Abstract:

    The first transmembrane (TM1) helix in the red cell anion exchanger (AE1, Band 3, or SLC4A1) acts as an Internal Signal anchor that binds the Signal recognition particle and directs the nascent polypeptide chain to the endoplasmic reticulum (ER) membrane where it moves from the translocon laterally into the lipid bilayer. The sequence N-terminal to TM1 forms an amphipathic helix that lies at the membrane interface and is connected to TM1 by a bend at Pro403. Southeast Asian ovalocytosis (SAO) is a red cell abnormality caused by a nine-amino acid deletion (Ala400–Ala408) at the N-terminus of TM1. Here we demonstrate, by extensive (∼4.5 μs) molecular dynamics simulations of TM1 in a model 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine membrane, that the isolated TM1 peptide is highly dynamic and samples the structure of TM1 seen in the crystal structure of the membrane domain of AE1. The SAO deletion not only removes the proline-induced bend but also causes a “pulling in” of the part of the amphipathic he...

  • Effect of the Southeast Asian Ovalocytosis Deletion on the Conformational Dynamics of Signal-Anchor Transmembrane Segment 1 of Red Cell Anion Exchanger 1 (AE1, Band 3, or SLC4A1)
    2017
    Co-Authors: Philip W Fowler, Mark S P Sansom, Reinhart A F Reithmeier
    Abstract:

    The first transmembrane (TM1) helix in the red cell anion exchanger (AE1, Band 3, or SLC4A1) acts as an Internal Signal anchor that binds the Signal recognition particle and directs the nascent polypeptide chain to the endoplasmic reticulum (ER) membrane where it moves from the translocon laterally into the lipid bilayer. The sequence N-terminal to TM1 forms an amphipathic helix that lies at the membrane interface and is connected to TM1 by a bend at Pro403. Southeast Asian ovalocytosis (SAO) is a red cell abnormality caused by a nine-amino acid deletion (Ala400–Ala408) at the N-terminus of TM1. Here we demonstrate, by extensive (∼4.5 μs) molecular dynamics simulations of TM1 in a model 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine membrane, that the isolated TM1 peptide is highly dynamic and samples the structure of TM1 seen in the crystal structure of the membrane domain of AE1. The SAO deletion not only removes the proline-induced bend but also causes a “pulling in” of the part of the amphipathic helix into the hydrophobic phase of the bilayer, as well as the C-terminal of the peptide. The dynamics of the SAO peptide very infrequently resembles the structure of TM1 in AE1, demonstrating the disruptive effect the SAO deletion has on AE1 folding. These results provide a precise molecular view of the disposition and dynamics of wild-type and SAO TM1 in a lipid bilayer, an important early biosynthetic intermediate in the insertion of AE1 into the ER membrane, and extend earlier results of cell-free translation experiments