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  1. Article ; Online: Small Changes: Using Assessment to Direct Instructional Practices in Large-Enrollment Biochemistry Courses.

    Xu, Xiaoying / Lewis, Jennifer E / Loertscher, Jennifer / Minderhout, Vicky / Tienson, Heather L

    CBE life sciences education

    2017  Volume 16, Issue 1

    Abstract: Multiple-choice assessments provide a straightforward way for instructors of large classes to collect data related to student understanding of key concepts at the beginning and end of a course. By tracking student performance over time, instructors ... ...

    Abstract Multiple-choice assessments provide a straightforward way for instructors of large classes to collect data related to student understanding of key concepts at the beginning and end of a course. By tracking student performance over time, instructors receive formative feedback about their teaching and can assess the impact of instructional changes. The evidence of instructional effectiveness can in turn inform future instruction, and vice versa. In this study, we analyzed student responses on an optimized pretest and posttest administered during four different quarters in a large-enrollment biochemistry course. Student performance and the effect of instructional interventions related to three fundamental concepts-hydrogen bonding, bond energy, and pK
    MeSH term(s) Biochemistry/education ; Comprehension ; Formative Feedback ; Humans ; Knowledge ; Students/psychology ; Teaching
    Language English
    Publishing date 2017
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, Non-U.S. Gov't
    ZDB-ID 2465176-X
    ISSN 1931-7913 ; 1931-7913
    ISSN (online) 1931-7913
    ISSN 1931-7913
    DOI 10.1187/cbe.16-06-0191
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Redox regulation of protein folding in the mitochondrial intermembrane space.

    Koehler, Carla M / Tienson, Heather L

    Biochimica et biophysica acta

    2008  Volume 1793, Issue 1, Page(s) 139–145

    Abstract: Protein translocation pathways to the mitochondrial matrix and inner membrane have been well characterized. However, translocation into the intermembrane space, which was thought to be simply a modification of the traditional translocation pathways, is ... ...

    Abstract Protein translocation pathways to the mitochondrial matrix and inner membrane have been well characterized. However, translocation into the intermembrane space, which was thought to be simply a modification of the traditional translocation pathways, is complex. The mechanism by which a subset of intermembrane space proteins, those with disulfide bonds, are translocated has been largely unknown until recently. Specifically, the intermembrane space proteins with disulfide bonds are imported via the mitochondrial intermembrane space assembly (MIA) pathway. Substrates are imported via a disulfide exchange relay with two components Mia40 and Erv1. This new breakthrough has resulted in novel concepts for assembly of proteins in the intermembrane space, suggesting that this compartment may be similar to that of the endoplasmic reticulum and the prokaryotic periplasm. As a better understanding of this pathway emerges, new paradigms for thiol-disulfide exchange mechanisms may be developed. Given that the intermembrane space is important for disease processes including apoptosis and neurodegeneration, new roles in regulation by oxidation-reduction chemistry seem likely to be relevant.
    MeSH term(s) Animals ; Humans ; Mitochondrial Membranes/metabolism ; Mitochondrial Proteins/chemistry ; Mitochondrial Proteins/metabolism ; Models, Biological ; Oxidation-Reduction ; Protein Folding ; Protein Transport/physiology
    Chemical Substances Mitochondrial Proteins
    Language English
    Publishing date 2008-08-13
    Publishing country Netherlands
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 60-7
    ISSN 1879-2596 ; 1879-260X ; 1872-8006 ; 1879-2642 ; 1879-2618 ; 1879-2650 ; 0006-3002 ; 0005-2728 ; 0005-2736 ; 0304-4165 ; 0167-4838 ; 1388-1981 ; 0167-4889 ; 0167-4781 ; 0304-419X ; 1570-9639 ; 0925-4439 ; 1874-9399
    ISSN (online) 1879-2596 ; 1879-260X ; 1872-8006 ; 1879-2642 ; 1879-2618 ; 1879-2650
    ISSN 0006-3002 ; 0005-2728 ; 0005-2736 ; 0304-4165 ; 0167-4838 ; 1388-1981 ; 0167-4889 ; 0167-4781 ; 0304-419X ; 1570-9639 ; 0925-4439 ; 1874-9399
    DOI 10.1016/j.bbamcr.2008.08.002
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Mia40 Protein Serves as an Electron Sink in the Mia40-Erv1 Import Pathway.

    Neal, Sonya E / Dabir, Deepa V / Tienson, Heather L / Horn, Darryl M / Glaeser, Kathrin / Ogozalek Loo, Rachel R / Barrientos, Antoni / Koehler, Carla M

    The Journal of biological chemistry

    2015  Volume 290, Issue 34, Page(s) 20804–20814

    Abstract: A redox-regulated import pathway consisting of Mia40 and Erv1 mediates the import of cysteine-rich proteins into the mitochondrial intermembrane space. Mia40 is the oxidoreductase that inserts two disulfide bonds into the substrate simultaneously. ... ...

    Abstract A redox-regulated import pathway consisting of Mia40 and Erv1 mediates the import of cysteine-rich proteins into the mitochondrial intermembrane space. Mia40 is the oxidoreductase that inserts two disulfide bonds into the substrate simultaneously. However, Mia40 has one redox-active cysteine pair, resulting in ambiguity about how Mia40 accepts numerous electrons during substrate oxidation. In this study, we have addressed the oxidation of Tim13 in vitro and in organello. Reductants such as glutathione and ascorbate inhibited both the oxidation of the substrate Tim13 in vitro and the import of Tim13 and Cmc1 into isolated mitochondria. In addition, a ternary complex consisting of Erv1, Mia40, and substrate, linked by disulfide bonds, was not detected in vitro. Instead, Mia40 accepted six electrons from substrates, and this fully reduced Mia40 was sensitive to protease, indicative of conformational changes in the structure. Mia40 in mitochondria from the erv1-101 mutant was also trapped in a completely reduced state, demonstrating that Mia40 can accept up to six electrons as substrates are imported. Therefore, these studies support that Mia40 functions as an electron sink to facilitate the insertion of two disulfide bonds into substrates.
    MeSH term(s) Ascorbic Acid/pharmacology ; Disulfides/chemistry ; Disulfides/metabolism ; Electrons ; Gene Expression Regulation, Fungal ; Glutathione/pharmacology ; Metallochaperones/genetics ; Metallochaperones/metabolism ; Mitochondria/drug effects ; Mitochondria/metabolism ; Mitochondrial Membrane Transport Proteins/genetics ; Mitochondrial Membrane Transport Proteins/metabolism ; Mitochondrial Proteins/genetics ; Mitochondrial Proteins/metabolism ; Mutation ; Oxidation-Reduction ; Oxidoreductases Acting on Sulfur Group Donors/genetics ; Oxidoreductases Acting on Sulfur Group Donors/metabolism ; Plasmids/chemistry ; Plasmids/metabolism ; Protein Transport ; Recombinant Proteins/genetics ; Recombinant Proteins/metabolism ; Reducing Agents/pharmacology ; Saccharomyces cerevisiae/drug effects ; Saccharomyces cerevisiae/genetics ; Saccharomyces cerevisiae/metabolism ; Saccharomyces cerevisiae Proteins/genetics ; Saccharomyces cerevisiae Proteins/metabolism ; Signal Transduction
    Chemical Substances CMC1 protein, S cerevisiae ; Disulfides ; MIA40 protein, S cerevisiae ; Metallochaperones ; Mitochondrial Membrane Transport Proteins ; Mitochondrial Proteins ; Recombinant Proteins ; Reducing Agents ; Saccharomyces cerevisiae Proteins ; TIM13 protein, S cerevisiae ; Oxidoreductases Acting on Sulfur Group Donors (EC 1.8.-) ; ERV1 protein, S cerevisiae (EC 1.8.3.2) ; Glutathione (GAN16C9B8O) ; Ascorbic Acid (PQ6CK8PD0R)
    Language English
    Publishing date 2015-06-17
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1074/jbc.M115.669440
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Role of twin Cys-Xaa9-Cys motif cysteines in mitochondrial import of the cytochrome C oxidase biogenesis factor Cmc1.

    Bourens, Myriam / Dabir, Deepa V / Tienson, Heather L / Sorokina, Irina / Koehler, Carla M / Barrientos, Antoni

    The Journal of biological chemistry

    2012  Volume 287, Issue 37, Page(s) 31258–31269

    Abstract: The Mia40 import pathway facilitates the import and oxidative folding of cysteine-rich protein substrates into the mitochondrial intermembrane space. Here we describe the in vitro and in organello oxidative folding of Cmc1, a twin CX(9)C-containing ... ...

    Abstract The Mia40 import pathway facilitates the import and oxidative folding of cysteine-rich protein substrates into the mitochondrial intermembrane space. Here we describe the in vitro and in organello oxidative folding of Cmc1, a twin CX(9)C-containing substrate, which contains an unpaired cysteine. In vitro, Cmc1 can be oxidized by the import receptor Mia40 alone when in excess or at a lower rate by only the sulfhydryl oxidase Erv1. However, physiological and efficient Cmc1 oxidation requires Erv1 and Mia40. Cmc1 forms a stable intermediate with Mia40 and is released from this interaction in the presence of Erv1. The three proteins are shown to form a ternary complex in mitochondria. Our results suggest that this mechanism facilitates efficient formation of multiple disulfides and prevents the formation of non-native disulfide bonds.
    MeSH term(s) Amino Acid Motifs ; Metallochaperones/genetics ; Metallochaperones/metabolism ; Mitochondria/genetics ; Mitochondria/metabolism ; Mitochondrial Membrane Transport Proteins/genetics ; Mitochondrial Membrane Transport Proteins/metabolism ; Mitochondrial Precursor Protein Import Complex Proteins ; Mitochondrial Proteins/genetics ; Mitochondrial Proteins/metabolism ; Multiprotein Complexes/genetics ; Multiprotein Complexes/metabolism ; Oxidation-Reduction ; Oxidoreductases Acting on Sulfur Group Donors/genetics ; Oxidoreductases Acting on Sulfur Group Donors/metabolism ; Protein Binding ; Protein Transport/physiology ; Saccharomyces cerevisiae/genetics ; Saccharomyces cerevisiae/metabolism ; Saccharomyces cerevisiae Proteins/genetics ; Saccharomyces cerevisiae Proteins/metabolism
    Chemical Substances CMC1 protein, S cerevisiae ; MIA40 protein, S cerevisiae ; Metallochaperones ; Mitochondrial Membrane Transport Proteins ; Mitochondrial Precursor Protein Import Complex Proteins ; Mitochondrial Proteins ; Multiprotein Complexes ; Saccharomyces cerevisiae Proteins ; Oxidoreductases Acting on Sulfur Group Donors (EC 1.8.-) ; ERV1 protein, S cerevisiae (EC 1.8.3.2)
    Language English
    Publishing date 2012-07-05
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1074/jbc.M112.383562
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Tim54p connects inner membrane assembly and proteolytic pathways in the mitochondrion

    Hwang, David K / Claypool, Steven M / Leuenberger, Danielle / Tienson, Heather L / Koehler, Carla M

    Journal of cell biology. 2007 Sept. 24, v. 178, no. 7

    2007  

    Abstract: Tim54p, a component of the inner membrane TIM22 complex, does not directly mediate the import of inner membrane substrates but is required for assembly/stability of the 300-kD TIM22 complex. In addition, Δtim54 yeast exhibit a petite-negative phenotype ( ... ...

    Abstract Tim54p, a component of the inner membrane TIM22 complex, does not directly mediate the import of inner membrane substrates but is required for assembly/stability of the 300-kD TIM22 complex. In addition, Δtim54 yeast exhibit a petite-negative phenotype (also observed in yeast harboring mutations in the F1Fo ATPase, the ADP/ATP carrier, mitochondrial morphology components, or the i-AAA protease, Yme1p). Interestingly, other import mutants in our strain background are not petite-negative. We report that Tim54p is not involved in maintenance of mitochondrial DNA or mitochondrial morphology. Rather, Tim54p mediates assembly of an active Yme1p complex, after Yme1p is imported via the TIM23 pathway. Defective Yme1p assembly is likely the major contributing factor for the petite-negativity in strains lacking functional Tim54p. Thus, Tim54p has two independent functions: scaffolding/stability for the TIM22 membrane complex and assembly of Yme1p into a proteolytically active complex. As such, Tim54p links protein import, assembly, and turnover pathways in the mitochondrion.
    Language English
    Dates of publication 2007-0924
    Size p. 1161-1175.
    Publishing place The Rockefeller University Press
    Document type Article
    ZDB-ID 218154-x
    ISSN 1540-8140 ; 0021-9525
    ISSN (online) 1540-8140
    ISSN 0021-9525
    Database NAL-Catalogue (AGRICOLA)

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  6. Article: Tim54p connects inner membrane assembly and proteolytic pathways in the mitochondrion.

    Hwang, David K / Claypool, Steven M / Leuenberger, Danielle / Tienson, Heather L / Koehler, Carla M

    The Journal of cell biology

    2007  Volume 178, Issue 7, Page(s) 1161–1175

    Abstract: Tim54p, a component of the inner membrane TIM22 complex, does not directly mediate the import of inner membrane substrates but is required for assembly/stability of the 300-kD TIM22 complex. In addition, Deltatim54 yeast exhibit a petite-negative ... ...

    Abstract Tim54p, a component of the inner membrane TIM22 complex, does not directly mediate the import of inner membrane substrates but is required for assembly/stability of the 300-kD TIM22 complex. In addition, Deltatim54 yeast exhibit a petite-negative phenotype (also observed in yeast harboring mutations in the F1Fo ATPase, the ADP/ATP carrier, mitochondrial morphology components, or the i-AAA protease, Yme1p). Interestingly, other import mutants in our strain background are not petite-negative. We report that Tim54p is not involved in maintenance of mitochondrial DNA or mitochondrial morphology. Rather, Tim54p mediates assembly of an active Yme1p complex, after Yme1p is imported via the TIM23 pathway. Defective Yme1p assembly is likely the major contributing factor for the petite-negativity in strains lacking functional Tim54p. Thus, Tim54p has two independent functions: scaffolding/stability for the TIM22 membrane complex and assembly of Yme1p into a proteolytically active complex. As such, Tim54p links protein import, assembly, and turnover pathways in the mitochondrion.
    MeSH term(s) ATP-Dependent Proteases ; Adenosine Triphosphatases/metabolism ; DNA, Mitochondrial/metabolism ; Gene Expression ; Glucose/metabolism ; Membrane Transport Proteins/metabolism ; Microbial Viability ; Mitochondria/metabolism ; Mitochondrial Membrane Transport Proteins/deficiency ; Mitochondrial Membrane Transport Proteins/metabolism ; Mitochondrial Membranes/metabolism ; Models, Biological ; Mutation/genetics ; Protein Binding ; Protein Processing, Post-Translational ; Protein Transport ; Saccharomyces cerevisiae/cytology ; Saccharomyces cerevisiae/metabolism ; Saccharomyces cerevisiae Proteins/metabolism
    Chemical Substances DNA, Mitochondrial ; Membrane Transport Proteins ; Mitochondrial Membrane Transport Proteins ; Saccharomyces cerevisiae Proteins ; TIM22 protein, S cerevisiae ; TIM54 protein, S cerevisiae ; ATP-Dependent Proteases (EC 3.4.21.-) ; YME1 protein, S cerevisiae (EC 3.4.21.-) ; Adenosine Triphosphatases (EC 3.6.1.-) ; Glucose (IY9XDZ35W2)
    Language English
    Publishing date 2007-09-24
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 218154-x
    ISSN 1540-8140 ; 0021-9525
    ISSN (online) 1540-8140
    ISSN 0021-9525
    DOI 10.1083/jcb.200706195
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: An approach to crystallizing proteins by synthetic symmetrization.

    Banatao, D Rey / Cascio, Duilio / Crowley, Christopher S / Fleissner, Mark R / Tienson, Heather L / Yeates, Todd O

    Proceedings of the National Academy of Sciences of the United States of America

    2006  Volume 103, Issue 44, Page(s) 16230–16235

    Abstract: Previous studies of symmetry preferences in protein crystals suggest that symmetric proteins, such as homodimers, might crystallize more readily on average than asymmetric, monomeric proteins. Proteins that are naturally monomeric can be made homodimeric ...

    Abstract Previous studies of symmetry preferences in protein crystals suggest that symmetric proteins, such as homodimers, might crystallize more readily on average than asymmetric, monomeric proteins. Proteins that are naturally monomeric can be made homodimeric artificially by forming disulfide bonds between individual cysteine residues introduced by mutagenesis. Furthermore, by creating a variety of single-cysteine mutants, a series of distinct synthetic dimers can be generated for a given protein of interest, with each expected to gain advantage from its added symmetry and to exhibit a crystallization behavior distinct from the other constructs. This strategy was tested on phage T4 lysozyme, a protein whose crystallization as a monomer has been studied exhaustively. Experiments on three single-cysteine mutants, each prepared in dimeric form, yielded numerous novel crystal forms that cannot be realized by monomeric lysozyme. Six new crystal forms have been characterized. The results suggest that synthetic symmetrization may be a useful approach for enlarging the search space for crystallizing proteins.
    MeSH term(s) Crystallization ; Dimerization ; Models, Molecular ; Muramidase/chemistry ; Muramidase/genetics ; Mutation/genetics ; Protein Binding ; Protein Structure, Quaternary ; Protein Structure, Tertiary
    Chemical Substances Muramidase (EC 3.2.1.17)
    Language English
    Publishing date 2006-10-18
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.0607674103
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Reconstitution of the mia40-erv1 oxidative folding pathway for the small tim proteins.

    Tienson, Heather L / Dabir, Deepa V / Neal, Sonya E / Loo, Rachel / Hasson, Samuel A / Boontheung, Pinmanee / Kim, Sung-Kun / Loo, Joseph A / Koehler, Carla M

    Molecular biology of the cell

    2009  Volume 20, Issue 15, Page(s) 3481–3490

    Abstract: Mia40 and Erv1 execute a disulfide relay to import the small Tim proteins into the mitochondrial intermembrane space. Here, we have reconstituted the oxidative folding pathway in vitro with Tim13 as a substrate and determined the midpoint potentials of ... ...

    Abstract Mia40 and Erv1 execute a disulfide relay to import the small Tim proteins into the mitochondrial intermembrane space. Here, we have reconstituted the oxidative folding pathway in vitro with Tim13 as a substrate and determined the midpoint potentials of Mia40 and Tim13. Specifically, Mia40 served as a direct oxidant of Tim13, and Erv1 was required to reoxidize Mia40. During oxidation, four electrons were transferred from Tim13 with the insertion of two disulfide bonds in succession. The extent of Tim13 oxidation was directly dependent on Mia40 concentration and independent of Erv1 concentration. Characterization of the midpoint potentials showed that electrons flowed from Tim13 with a more negative midpoint potential of -310 mV via Mia40 with an intermediate midpoint potential of -290 mV to the C130-C133 pair of Erv1 with a positive midpoint potential of -150 mV. Intermediary complexes between Tim13-Mia40 and Mia40-Erv1 were trapped. Last, mutating C133 of the catalytic C130-C133 pair or C30 of the shuttle C30-C33 pair in Erv1 abolished oxidation of Tim13, whereas mutating the cysteines in the redox-active CPC motif, but not the structural disulfide linkages of the CX(9)C motif of Mia40, prevented Tim13 oxidation. Thus, we demonstrate that Mia40, Erv1, and oxygen are the minimal machinery for Tim13 oxidation.
    MeSH term(s) Circular Dichroism ; Disulfides/chemistry ; Disulfides/metabolism ; Electrophoresis, Polyacrylamide Gel ; Hydrogen Peroxide/chemistry ; Hydrogen Peroxide/metabolism ; Mitochondrial Membrane Transport Proteins/chemistry ; Mitochondrial Membrane Transport Proteins/genetics ; Mitochondrial Membrane Transport Proteins/metabolism ; Mitochondrial Proteins/chemistry ; Mitochondrial Proteins/genetics ; Mitochondrial Proteins/metabolism ; Oxidation-Reduction ; Oxidoreductases Acting on Sulfur Group Donors/chemistry ; Oxidoreductases Acting on Sulfur Group Donors/genetics ; Oxidoreductases Acting on Sulfur Group Donors/metabolism ; Protein Folding ; Saccharomyces cerevisiae Proteins/chemistry ; Saccharomyces cerevisiae Proteins/genetics ; Saccharomyces cerevisiae Proteins/metabolism ; Signal Transduction ; Toluene/analogs & derivatives ; Toluene/chemistry ; Toluene/metabolism
    Chemical Substances Disulfides ; MIA40 protein, S cerevisiae ; Mitochondrial Membrane Transport Proteins ; Mitochondrial Proteins ; Saccharomyces cerevisiae Proteins ; TIM13 protein, S cerevisiae ; Toluene (3FPU23BG52) ; Hydrogen Peroxide (BBX060AN9V) ; Oxidoreductases Acting on Sulfur Group Donors (EC 1.8.-) ; ERV1 protein, S cerevisiae (EC 1.8.3.2) ; dithiol (U89B11P7SC)
    Language English
    Publishing date 2009-05-28
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 1098979-1
    ISSN 1939-4586 ; 1059-1524
    ISSN (online) 1939-4586
    ISSN 1059-1524
    DOI 10.1091/mbc.E08-10-1062
    Database MEDical Literature Analysis and Retrieval System OnLINE

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