Cleavage - Explore the Science & Experts | ideXlab

Scan Science and Technology

Contact Leading Edge Experts & Companies

Cleavage

The Experts below are selected from a list of 734721 Experts worldwide ranked by ideXlab platform

Cleavage – Free Register to Access Experts & Abstracts

Hans-georg Kräusslich – One of the best experts on this subject based on the ideXlab platform.

  • sequential steps in human immunodeficiency virus particle maturation revealed by alterations of individual gag polyprotein Cleavage sites
    Journal of Virology, 1998
    Co-Authors: Klaus Wiegers, Gabriel Rutter, Hubert Kottler, Uwe Tessmer, Heinz Hohenberg, Hans-georg Kräusslich
    Abstract:

    Retroviruses are produced as immature particles containing structural polyproteins, which are subsequently cleaved by the viral proteinase (PR). Extracellular maturation leads to condensation of the spherical core to a capsid shell formed by the capsid (CA) protein, which encases the genomic RNA complexed with nucleocapsid (NC) proteins. CA and NC are separated by a short spacer peptide (spacer peptide 1 [SP1]) on the human immunodeficiency viruvirus type 1 (HIV-1) Gag polyprotein and released by sequential PR-mediated Cleavages. To assess the role of individual Cleavages in maturation, we constructed point mutations abolishing Cleavage at these sites, either alone or in combination. When all three sites between CA and NC were mutated, immature particles containing stable CA-NC were observed, with no apparent effect on other Cleavages. Delayed maturation with irregular morphology of the ribonucleoprotein core was observed when Cleavage of SP1 from NC was prevented. Blocking the release of SP1 from CA, on the other hand, yielded normal condensation of the ribonucleoprotein core but prevented capsid condensation. A thin, electron-dense layer near the viral membrane was observed in this case, and mutant capsids were significantly less stable against detergent treatment than wild-type HIV-1. We suggest that HIV maturation is a sequential process controlled by the rate of Cleavage at individual sites. Initial rapid Cleavage at the C terminus of SP1 releases the RNA-binding NC protein and leads to condensation of the ribonucleoprotein core. Subsequently, CA is separated from the membrane by Cleavage between the matrix protein and CA, and late release of SP1 from CA is required for capsid condensation.

  • sequential steps in human immunodeficiency virus particle maturation revealed by alterations of individual gag polyprotein Cleavage sites
    Journal of Virology, 1998
    Co-Authors: Klaus Wiegers, Gabriel Rutter, Hubert Kottler, Uwe Tessmer, Heinz Hohenberg, Hans-georg Kräusslich
    Abstract:

    Retroviruses are produced as immature particles containing structural polyproteins, which are subsequently cleaved by the viral proteinase (PR). Extracellular maturation leads to condensation of the spherical core to a capsid shell formed by the capsid (CA) protein, which encases the genomic RNA complexed with nucleocapsid (NC) proteins. CA and NC are separated by a short spacer peptide (spacer peptide 1 [SP1]) on the human immunodeficiency viruvirus type 1 (HIV-1) Gag polyprotein and released by sequential PR-mediated Cleavages. To assess the role of individual Cleavages in maturation, we constructed point mutations abolishing Cleavage at these sites, either alone or in combination. When all three sites between CA and NC were mutated, immature particles containing stable CA-NC were observed, with no apparent effect on other Cleavages. Delayed maturation with irregular morphology of the ribonucleoprotein core was observed when Cleavage of SP1 from NC was prevented. Blocking the release of SP1 from CA, on the other hand, yielded normal condensation of the ribonucleoprotein core but prevented capsid condensation. A thin, electron-dense layer near the viral membrane was observed in this case, and mutant capsids were significantly less stable against detergent treatment than wild-type HIV-1. We suggest that HIV maturation is a sequential process controlled by the rate of Cleavage at individual sites. Initial rapid Cleavage at the C terminus of SP1 releases the RNA-binding NC protein and leads to condensation of the ribonucleoprotein core. Subsequently, CA is separated from the membrane by Cleavage between the matrix protein and CA, and late release of SP1 from CA is required for capsid condensation.

J. Dubuisson – One of the best experts on this subject based on the ideXlab platform.

  • regulation of hepatitis c virus polyprotein processing by signal peptidase involves structural determinants at the p7 sequence junctions
    Journal of Biological Chemistry, 2004
    Co-Authors: Severine Carrerekremer, C. Montpellier, L. Lorenzo, B. Brulin, L. Cocquerel, S. Belouzard, F. Penin, J. Dubuisson
    Abstract:

    Abstract The hepatitis C virus genome encodes a polyprotein precursor that is co- and post-translationally processed by cellular and viral proteases to yield 10 mature protein products (C, E1, E2, p7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B). Although most Cleavages in hepatitis C virus polyprotein precursor proceed to completion during or immediately after translation, the Cleavages mediated by a host cell signal peptidase are partial at the E2/p7 and p7/NS2 sites, leading to the production of an E2p7NS2 precursor. The sequences located immediately N-terminally of E2/p7 and p7/NS2 Cleavage sites can function as signal peptides. When fused to a reporter protein, the signal peptides of p7 and NS2 were efficiently cleaved. However, when full-length p7 was fused to the reporter protein, partial Cleavage was observed, indicating that a sequence located N-terminally of the signal peptpeptide reduces the efficiency of p7/NS2 Cleavage. Sequence analyses and mutagenesis studies have also identified structural determinants responsible for the partial Cleavage at both the E2/p7 and p7/NS2 sites. Finally, the short distance between the Cleavage site of E2/p7 or p7/NS2 and the predicted transmembrane α-helix within the P′ region might impose additional structural constraints to the Cleavage sites. The insertion of a linker polypeptide sequence between P-3′ and P-4′ of the Cleavage site released these constraints and led to improved Cleavage efficiency. Such constraints in the processing of a polyprotein precursor are likely essential for hepatitis C virus to post-translationally regulate the kinetics and/or the level of expression of p7 as well as NS2 and E2 mature proteins.

  • Regulation of hepatitis C virus polyprotein processing by signal peptidase involves structural determinants at the p7 sequence junctions.
    Journal of Biological Chemistry, 2004
    Co-Authors: S. Carrere-kremer, C. Montpellier, L. Lorenzo, B. Brulin, L. Cocquerel, S. Belouzard, F. Penin, J. Dubuisson
    Abstract:

    The hepatitis C virus genome encodes a polyprotein precursor that is co- and post-translationally processed by cellular and viral proteases to yield 10 mature protein products (C, E1, E2, p7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B). Although most Cleavages in hepatitis C virus polyprotein precursor proceed to completion during or immediately after translation, the Cleavages mediated by a host cell signal peptidase are partial at the E2/p7 and p7/NS2 sites, leading to the production of an E2p7NS2 precursor. The sequences located immediately N-terminally of E2/p7 and p7/NS2 Cleavage sites can function as signal peptides. When fused to a reporter protein, the signal peptides of p7 and NS2 were efficiently cleaved. However, when full-length p7 was fused to the reporter protein, partial Cleavage was observed, indicating that a sequence located N-terminally of the signal peptpeptide reduces the efficiency of p7/NS2 Cleavage. Sequence analyses and mutagenesis studies have also identified structural determinants responsible for the partial Cleavage at both the E2/p7 and p7/NS2 sites. Finally, the short distance between the Cleavage site of E2/p7 or p7/NS2 and the predicted transmembrane alpha-helix within the P’ region might impose additional structural constraints to the Cleavage sites. The insertion of a linker polypeptide sequence between P-3′ and P-4′ of the Cleavage site released these constraints and led to improved Cleavage efficiency. Such constraints in the processing of a polyprotein precursor are likely essential for hepatitis C virus to post-translationally regulate the kinetics and/or the level of expression of p7 as well as NS2 and E2 mature proteins.The hepatitis C virus genome encodes a polyprotein precursor that is co- and post-translationally processed by cellular and viral proteases to yield 10 mature protein products (C, E1, E2, p7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B). Although most Cleavages in hepatitis C virus polyprotein precursor proceed to completion during or immediately after translation, the Cleavages mediated by a host cell signal peptidase are partial at the E2/p7 and p7/NS2 sites, leading to the production of an E2p7NS2 precursor. The sequences located immediately N-terminally of E2/p7 and p7/NS2 Cleavage sites can function as signal peptides. When fused to a reporter protein, the signal peptides of p7 and NS2 were efficiently cleaved. However, when full-length p7 was fused to the reporter protein, partial Cleavage was observed, indicating that a sequence located N-terminally of the signal peptpeptide reduces the efficiency of p7/NS2 Cleavage. Sequence analyses and mutagenesis studies have also identified structural determinants responsible for the partial Cleavage at both the E2/p7 and p7/NS2 sites. Finally, the short distance between the Cleavage site of E2/p7 or p7/NS2 and the predicted transmembrane alpha-helix within the P’ region might impose additional structural constraints to the Cleavage sites. The insertion of a linker polypeptide sequence between P-3′ and P-4′ of the Cleavage site released these constraints and led to improved Cleavage efficiency. Such constraints in the processing of a polyprotein precursor are likely essential for hepatitis C virus to post-translationally regulate the kinetics and/or the level of expression of p7 as well as NS2 and E2 mature proteins.

Klaus Wiegers – One of the best experts on this subject based on the ideXlab platform.

  • sequential steps in human immunodeficiency virus particle maturation revealed by alterations of individual gag polyprotein Cleavage sites
    Journal of Virology, 1998
    Co-Authors: Klaus Wiegers, Gabriel Rutter, Hubert Kottler, Uwe Tessmer, Heinz Hohenberg, Hans-georg Kräusslich
    Abstract:

    Retroviruses are produced as immature particles containing structural polyproteins, which are subsequently cleaved by the viral proteinase (PR). Extracellular maturation leads to condensation of the spherical core to a capsid shell formed by the capsid (CA) protein, which encases the genomic RNA complexed with nucleocapsid (NC) proteins. CA and NC are separated by a short spacer peptide (spacer peptide 1 [SP1]) on the human immunodeficiency virus type 1 (HIV-1) Gag polyprotein and released by sequential PR-mediated Cleavages. To assess the role of individual Cleavages in maturation, we constructed point mutations abolishing Cleavage at these sites, either alone or in combination. When all three sites between CA and NC were mutated, immature particles containing stable CA-NC were observed, with no apparent effect on other Cleavages. Delayed maturation with irregular morphology of the ribonucleoprotein core was observed when Cleavage of SP1 from NC was prevented. Blocking the release of SP1 from CA, on the other hand, yielded normal condensation of the ribonucleoprotein core but prevented capsid condensation. A thin, electron-dense layer near the viral membrane was observed in this case, and mutant capsids were significantly less stable against detergent treatment than wild-type HIV-1. We suggest that HIV maturation is a sequential process controlled by the rate of Cleavage at individual sites. Initial rapid Cleavage at the C terminus of SP1 releases the RNA-binding NC protein and leads to condensation of the ribonucleoprotein core. Subsequently, CA is separated from the membrane by Cleavage between the matrix protein and CA, and late release of SP1 from CA is required for capsid condensation.

  • sequential steps in human immunodeficiency virus particle maturation revealed by alterations of individual gag polyprotein Cleavage sites
    Journal of Virology, 1998
    Co-Authors: Klaus Wiegers, Gabriel Rutter, Hubert Kottler, Uwe Tessmer, Heinz Hohenberg, Hans-georg Kräusslich
    Abstract:

    Retroviruses are produced as immature particles containing structural polyproteins, which are subsequently cleaved by the viral proteinase (PR). Extracellular maturation leads to condensation of the spherical core to a capsid shell formed by the capsid (CA) protein, which encases the genomic RNA complexed with nucleocapsid (NC) proteins. CA and NC are separated by a short spacer peptide (spacer peptide 1 [SP1]) on the human immunodeficiency virus type 1 (HIV-1) Gag polyprotein and released by sequential PR-mediated Cleavages. To assess the role of individual Cleavages in maturation, we constructed point mutations abolishing Cleavage at these sites, either alone or in combination. When all three sites between CA and NC were mutated, immature particles containing stable CA-NC were observed, with no apparent effect on other Cleavages. Delayed maturation with irregular morphology of the ribonucleoprotein core was observed when Cleavage of SP1 from NC was prevented. Blocking the release of SP1 from CA, on the other hand, yielded normal condensation of the ribonucleoprotein core but prevented capsid condensation. A thin, electron-dense layer near the viral membrane was observed in this case, and mutant capsids were significantly less stable against detergent treatment than wild-type HIV-1. We suggest that HIV maturation is a sequential process controlled by the rate of Cleavage at individual sites. Initial rapid Cleavage at the C terminus of SP1 releases the RNA-binding NC protein and leads to condensation of the ribonucleoprotein core. Subsequently, CA is separated from the membrane by Cleavage between the matrix protein and CA, and late release of SP1 from CA is required for capsid condensation.

Marc W Kirschner – One of the best experts on this subject based on the ideXlab platform.

  • Anaphase specific auto-Cleavage of separase.
    FEBS letters, 2002
    Co-Authors: Olaf Stemman, Jens S Anderson, Matthias Mann, Marc W Kirschner
    Abstract:

    Sister-chromatid separation is triggered by a specific proteolytic Cleavage of chromosomal cohesins catalyzed by the endopeptidase separase. Prior to anaphase, separase is inhibited independently by affinity binding to securin and by specific inhibitory phosphorylation. Here we show that separase itself is also subjected to proteolytic Cleavages at three adjacent sites. The Cleavages are auto-catalyzed and occur specifically at anaphase coincident with separase activation. The cleaved fragments remain associated with each other and are catalytically active. Mapping of the Cleavage sites reveals that all three sites are conserved in vertebrates underlining a significant function for this regulation.

Takashi Shimizu – One of the best experts on this subject based on the ideXlab platform.

  • Transcriptional control of unequal Cleavage in early Tubifex embryos
    Development Genes and Evolution, 2017
    Co-Authors: Momoe Aoki, Takashi Shimizu
    Abstract:

    Early embryos of the clitellate annelid Tubifex (oligochaete) undergo a series of unequal spiral cell divisions before the descendants of the D quadrant micromeres (cells 2d and 4d) divide bilaterally. Here, we show that inhibition of zygotic transcription by microinjection of α-amanitin (transcription inhibitor) exclusively converts unequal Cleavage in cell 2d^11 (granddaughter of 2d) into equal Cleavage while other unequal Cleavages and ensuing bilateral Cleavages in cells 4d and 2d^111 (great-granddaughter of 2d) all proceed in a normal fashion in the presence of this inhibitor. These results differ significantly from those reported for embryos of another clitellate annelid Helobdella (leech), in which inhibition of transcription converts bilateral (symmetric) Cleavages in cells DNOPQ”’ and DM” (equivalent to 2d^111 and 4d) into unequal (asymmetric) Cleavages while having no apparent effect on unequal Cleavage in DNOPQ” (equivalent to 2d^11). These differences imply distinct mechanisms for the control of the unequal-to-bilateral transition in the two clitellate annelids.

  • UNEQUAL Cleavage IN THE EARLY TUBIFEX EMBRYO
    Development growth & differentiation, 1998
    Co-Authors: Takashi Shimizu, Ryuichi Ishii, Hirokazu Takahashi
    Abstract:

    Unequal Cleavage that produces two blastomeres of different size is a Cleavage pattern that many animals in a variety of phyla, particularly in Spiralia, adopt during early development. This Cleavage pattern is apparently instrumental for asymmetric segregation of developmental potential, but it is also indispensable for normal embryogenesis in many animals. Mechanically, unequal Cleavage is achieved by either simple unequal cytokinesis or by forming a polar lobe at the egg’s vegetal pole. In the present paper, the mechanisms for unequal cytokinesis involved in the first three Cleavages in the oligochaete annelid Tubifex are reviewed. The three unequal Cleavages are all brought about by an asymmetrically organized mitotic apparatus (MA). The MA of the first Cleavage is monastral in that an aster is present at one pole of a bipolar spindle but not at the other. This monastral form, which arises as a result of the involvement of a single centrosome in the MA assembly, is both necessary and sufficient for unequal first Cleavage. The egg cortex during the first mitosis is devoid of the ability to remodel spindle poles. In contrast to the non-cortical mechanisms for the first Cleavage, asymmetry in the MA organization at the second and third Cleavages depends solely on specialized properties of the cell cortex, to which one spindle pole is physically connected. A cortical attachment site for the second Cleavage spindle is generated de novo at the Cleavage membrane resulting from the first Cleavage; it is an actin-based, cell contact-dependent structure. The cortical microtubule attachment site for the third Cleavage, which functions independently of contact with other cells, is not generated at the Cleavage membrane resulting from the second Cleavage, but is located at the animal pole; it may originate from the second polar body formation and become functional at the 4-cell stage.