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Relationship between the Stability of Hen Egg-White Lysozymes Mutated at Sites Designed to Interact with α-Helix Dipoles and Their Secretion Amounts in Yeast. Biosci Biotechnol Biochem 2014; 71:2952-61. [DOI: 10.1271/bbb.70354] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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2
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Gidalevitz T, Stevens F, Argon Y. Orchestration of secretory protein folding by ER chaperones. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1833:2410-24. [PMID: 23507200 PMCID: PMC3729627 DOI: 10.1016/j.bbamcr.2013.03.007] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 02/27/2013] [Accepted: 03/01/2013] [Indexed: 02/06/2023]
Abstract
The endoplasmic reticulum is a major compartment of protein biogenesis in the cell, dedicated to production of secretory, membrane and organelle proteins. The secretome has distinct structural and post-translational characteristics, since folding in the ER occurs in an environment that is distinct in terms of its ionic composition, dynamics and requirements for quality control. The folding machinery in the ER therefore includes chaperones and folding enzymes that introduce, monitor and react to disulfide bonds, glycans, and fluctuations of luminal calcium. We describe the major chaperone networks in the lumen and discuss how they have distinct modes of operation that enable cells to accomplish highly efficient production of the secretome. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
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Affiliation(s)
- Tali Gidalevitz
- Department of Biology, Drexel University, Drexel University, 418 Papadakis Integrated Science Bldg, 3245 Chestnut Street, Philadelphia, PA 19104
| | | | - Yair Argon
- Division of Cell Pathology, Department of Pathology and Lab Medicine, The Children's Hospital of Philadelphia and the University of Pennsylvania, 3615 Civic Center Blvd., Philadelphia, PA 19104, USA, , Phone: 267-426-5131, Fax: 267-426-5165)
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3
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Ahn M, De Genst E, Kaminski Schierle GS, Erdelyi M, Kaminski CF, Dobson CM, Kumita JR. Analysis of the native structure, stability and aggregation of biotinylated human lysozyme. PLoS One 2012; 7:e50192. [PMID: 23166837 PMCID: PMC3500338 DOI: 10.1371/journal.pone.0050192] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 10/22/2012] [Indexed: 11/29/2022] Open
Abstract
Fibril formation by mutational variants of human lysozyme is associated with a fatal form of hereditary non-neuropathic systemic amyloidosis. Defining the mechanistic details of lysozyme aggregation is of crucial importance for understanding the origin and progression of this disease and related misfolding conditions. In this study, we show that a biotin moiety can be introduced site-specifically at Lys33 of human lysozyme. We demonstrate, using biophysical techniques, that the structure and stability of the native-state of the protein are not detectably altered by this modification, and that the ability to form amyloid fibrils is unchanged. By taking advantage of biotin-avidin interactions, we show that super-resolution fluorescence microscopy can generate detailed images of the mature fibrils. This methodology can readily enable the introduction of additional probes into the protein, thereby providing the means through which to understand, in detail, the nature of the aggregation process of lysozyme and its variants under a variety of conditions.
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Affiliation(s)
- Minkoo Ahn
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Erwin De Genst
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Miklos Erdelyi
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
- National Physics Laboratory, Teddington, United Kingdom
| | - Clemens F. Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
| | | | - Janet R. Kumita
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
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4
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Kawamura S, Ohkuma M, Chijiiwa Y, Kohno D, Nakagawa H, Hirakawa H, Kuhara S, Torikata T. Role of disulfide bonds in goose-type lysozyme. FEBS J 2008; 275:2818-30. [PMID: 18430025 DOI: 10.1111/j.1742-4658.2008.06422.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The role of the two disulfide bonds (Cys4-Cys60 and Cys18-Cys29) in the activity and stability of goose-type (G-type) lysozyme was investigated using ostrich egg-white lysozyme as a model. Each of the two disulfide bonds was deleted separately or simultaneously by substituting both Cys residues with either Ser or Ala. No remarkable differences in secondary structure or catalytic activity were observed between the wild-type and mutant proteins. However, thermal and guanidine hydrochloride unfolding experiments revealed that the stabilities of mutants lacking one or both of the disulfide bonds were significantly decreased relative to those of the wild-type. The destabilization energies of mutant proteins agreed well with those predicted from entropic effects in the denatured state. The effects of deleting each disulfide bond on protein stability were found to be approximately additive, indicating that the individual disulfide bonds contribute to the stability of G-type lysozyme in an independent manner. Under reducing conditions, the thermal stability of the wild-type was decreased to a level nearly equivalent to that of a Cys-free mutant (C4S/C18S/C29S/C60S) in which all Cys residues were replaced by Ser. Moreover, the optimum temperature of the catalytic activity for the Cys-free mutant was downshifted by about 20 degrees C as compared with that of the wild-type. These results indicate that the formation of the two disulfide bonds is not essential for the correct folding into the catalytically active conformation, but is crucial for the structural stability of G-type lysozyme.
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Affiliation(s)
- Shunsuke Kawamura
- Department of Bioscience, School of Agriculture, Tokai University, Aso, Kumamoto, Japan.
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5
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Kumita JR, Johnson RJK, Alcocer MJC, Dumoulin M, Holmqvist F, McCammon MG, Robinson CV, Archer DB, Dobson CM. Impact of the native-state stability of human lysozyme variants on protein secretion by Pichia pastoris. FEBS J 2006; 273:711-20. [PMID: 16441658 DOI: 10.1111/j.1742-4658.2005.05099.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We report the secreted expression by Pichia pastoris of two human lysozyme variants F57I and W64R, associated with systemic amyloid disease, and describe their characterization by biophysical methods. Both variants have a substantially decreased thermostability compared with wild-type human lysozyme, a finding that suggests an explanation for their increased propensity to form fibrillar aggregates and generate disease. The secreted yields of the F57I and W64R variants from P. pastoris are 200- and 30-fold lower, respectively, than that of wild-type human lysozyme. More comprehensive analysis of the secretion levels of 10 lysozyme variants shows that the low yields of these secreted proteins, under controlled conditions, can be directly correlated with a reduction in the thermostability of their native states. Analysis of mRNA levels in this selection of variants suggests that the lower levels of secretion are due to post-transcriptional processes, and that the reduction in secreted protein is a result of degradation of partially folded or misfolded protein via the yeast quality control system. Importantly, our results show that the human disease-associated mutations do not have levels of expression that are out of line with destabilizing mutations at other sites. These findings indicate that a complex interplay between reduced native-state stability, lower secretion levels, and protein aggregation propensity influences the types of mutation that give rise to familial forms of amyloid disease.
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6
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Wain R, Smith LJ, Dobson CM. Oxidative refolding of amyloidogenic variants of human lysozyme. J Mol Biol 2005; 351:662-71. [PMID: 16023673 DOI: 10.1016/j.jmb.2005.06.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Revised: 06/13/2005] [Accepted: 06/15/2005] [Indexed: 11/22/2022]
Abstract
The oxidative refolding of human lysozyme and its two best characterised amyloidogenic variants, Ile56Thr and Asp67His, has been investigated in vitro by means of the concerted application of a range of biophysical techniques. The results show that in each case the ensemble of reduced denatured conformers initially collapses into a large number of unstructured intermediates with one or two disulphide bonds, the majority of which then fold to form the native-like three-disulphide intermediate, des-[77-95]. The slow step in the overall folding reaction involves the rearrangement of the latter to the fully oxidised native protein containing four disulphide bonds. The Ile56Thr and Asp67His variants were found to fold faster than the wild-type protein by a factor of 2 and 3 respectively, an observation that can be attributed primarily to the reduction in the barriers to conformational rearrangements that results from both the mutations. The efficient folding of these variants despite their enhanced propensities to aggregate when compared to the wild-type protein is consistent with their ability to be secreted in sufficient quantities to give rise to the systemic amyloidoses with which they are associated.
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Affiliation(s)
- Rachel Wain
- Oxford Centre for Molecular Sciences and Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, UK
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7
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Sekijima Y, Wiseman RL, Matteson J, Hammarström P, Miller SR, Sawkar AR, Balch WE, Kelly JW. The biological and chemical basis for tissue-selective amyloid disease. Cell 2005; 121:73-85. [PMID: 15820680 DOI: 10.1016/j.cell.2005.01.018] [Citation(s) in RCA: 366] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2004] [Revised: 01/19/2005] [Accepted: 01/21/2005] [Indexed: 11/19/2022]
Abstract
Factors controlling the onset and progression of extracellular amyloid diseases remain largely unknown. Central to disease etiology is the efficiency of the endoplasmic reticulum (ER) machinery that targets destabilized mutant proteins for degradation and the enhanced tendency of these variants to aggregate if secreted. We demonstrate that mammalian cells secrete numerous transthyretin (TTR) disease-associated variants with wild-type efficiency in spite of compromised folding energetics. Only the most highly destabilized TTR variants are subjected to ER-associated degradation (ERAD) and then only in certain tissues, providing insight into tissue selective amyloidosis. Rather than a "quality control" standard based on wild-type stability, we find that ER-assisted folding (ERAF), based on global protein energetics, determines the extent of export. We propose that ERAF (influenced by the energetics of the protein fold, chaperone enzyme distributions, and metabolite chaperones) in competition with ERAD defines the unique secretory aptitude of each tissue.
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Affiliation(s)
- Yoshiki Sekijima
- Department of Chemistry, The Skaggs Institute of Chemical Biology, The Skaggs Research Institute, 10550 N. Torrey Pines Road, BCC506, La Jolla, California 92037, USA
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8
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Badman ER, Hoaglund-Hyzer CS, Clemmer DE. Monitoring structural changes of proteins in an ion trap over approximately 10-200 ms: unfolding transitions in cytochrome c ions. Anal Chem 2001; 73:6000-7. [PMID: 11791572 DOI: 10.1021/ac010744a] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new technique for studying the time dependence of conformational changes of gas-phase protein ions is described. In this approach, a short pulse of electrosprayed protein ions is introduced into an ion trap and stored. After a defined time period, the distribution of ions is ejected from the trap into an ion mobility/time-of-flight mass spectrometer. Combined measurements of mobilities and flight times in the mass spectrometer provide information about the abundances of different conformer types and charge-state distributions. By varying the storage time in the trap, it is possible to monitor changes in ion conformation that occur over extended time periods (approximately 10-200 ms). The method is demonstrated by examining changes in cytochrome c ion conformations for the +7 to +10 charge states.
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Affiliation(s)
- E R Badman
- Department of Chemistry, Indiana University, Bloomington 47405, USA
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9
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Noyelle K, Joniau M, Van Dael H. The fast folding pathway in human lysozyme and its blockage by appropriate mutagenesis: a sequential stopped-flow fluorescence study 1 1Edited by C. R. Matthews. J Mol Biol 2001; 308:807-19. [PMID: 11350176 DOI: 10.1006/jmbi.2001.4620] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this work we were able to show that human lysozyme refolds along two parallel pathways: a fast path followed by 13% of the molecules that leads directly from a collapsed state to the native protein and a slow one for the remaining molecules that involves a partially unfolded intermediate state. However, in the refolding process of LYLA1, a chimera of human lysozyme which possesses the Ca2+-binding loop and helix C of bovine alpha-lactalbumin, the direct pathway is no longer accessible. This indicates that these structural elements, which are located in the interface region between the alpha- and beta-domain of the protein, and their interaction with the environment play an important role in the fast folding of the molecules. These results also shed some light on the conservation of folding patterns amongst structurally homologous proteins. In recent years it was often stated that structurally homologous proteins with high sequence identity follow the same folding pattern. Human lysozyme and LYLA1 have a sequence identity of 87%. However, we have shown that their folding patterns are different. Therefore, a high degree of sequence identity for two proteins belonging to the same family is not a guarantee for an identical folding pattern.
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Affiliation(s)
- K Noyelle
- Interdisciplinary Research Centre, K.U.Leuven Campus Kortrijk, Kortrijk, B-8500, Belgium
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10
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Masaki K, Aizawa T, Koganesawa N, Nimori T, Bando H, Kawano K, Nitta K. Thermal stability and enzymatic activity of a smaller lysozyme from silk moth (Bombyx mori). JOURNAL OF PROTEIN CHEMISTRY 2001; 20:107-13. [PMID: 11563690 DOI: 10.1023/a:1011073206353] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Bombyx mori lysozyme is 10 amino acids shorter than hen egg-white lysozyme, which is a typical c-type lysozyme. It was expressed by using the methylotrophic yeast Pichia pastoris. The thermal stability and the enzymatic activity of the Bombyx mori lysozyme were estimated and compared with those of human and hen egg-white lysozymes. The denaturation temperature was 17-26 degrees C lower than those of human and hen egg-white lysozymes. Further, the enthalpy change and the heat capacity change for unfolding were smaller than those of human lysozyme. It was also confirmed that the stability against guanidine hydrochloride was lower than those of the other two lysozymes. The enzymatic activity toward a simple synthetic substrate was measured and compared with those of human and hen egg-white lysozymes. The B-F binding mode was obviously dominant, although the A-E binding mode was preferred in human and hen egg-white lysozymes.
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Affiliation(s)
- K Masaki
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
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11
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Takano K, Funahashi J, Yutani K. The stability and folding process of amyloidogenic mutant human lysozymes. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:155-9. [PMID: 11121116 DOI: 10.1046/j.1432-1327.2001.01863.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Amyloid deposits are frequently formed by mutant proteins that have a lower stability than the wild-type proteins. Some reports, however, have shown that mutant-induced thermodynamic destabilization is not always a general mechanism of amyloid formation. To obtain a better understanding of the mechanism of amyloid fibril formation, we show in this study that equilibrium and kinetic refolding-unfolding reaction experiments with two amyloidogenic mutant human lysozymes (I56T and D67H) yield folding pathways that can be drawn as Gibbs energy diagrams. The equilibrium stabilities between the native and denatured states of both mutant proteins were decreased, but the degrees of instability were different. The Gibbs energy diagrams of the folding process reveal that the Gibbs energy change between the native and folding intermediate states was similar for both proteins, and also that the activation Gibbs energy change from the native state to the transition state decreased. Our results confirm that the tendency to favor the intermediate of denaturation facilitates amyloid formation by the mutant human lysozymes more than equilibrium destabilization between the native and completely denatured states does.
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Affiliation(s)
- K Takano
- Institute for Protein Research, Osaka University, Suita, Japan
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12
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Takano K, Yamagata Y, Yutani K. Role of amino acid residues at turns in the conformational stability and folding of human lysozyme. Biochemistry 2000; 39:8655-65. [PMID: 10913274 DOI: 10.1021/bi9928694] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To clarify the role of amino acid residues at turns in the conformational stability and folding of a globular protein, six mutant human lysozymes deleted or substituted at turn structures were investigated by calorimetry, GuHCl denaturation experiments, and X-ray crystal analysis. The thermodynamic properties of the mutant and wild-type human lysozymes were compared and discussed on the basis of their three-dimensional structures. For the deletion mutants, Delta47-48 and Delta101, the deleted residues are in turns on the surface and are absent in human alpha-lactalbumin, which is homologous to human lysozyme in amino acid sequence and tertiary structure. The stability of both mutants would be expected to increase due to a decrease in conformational entropy in the denatured state; however, both proteins were destabilized. The destabilizations were mainly caused by the disappearance of intramolecular hydrogen bonds. Each part deleted was recovered by the turn region like the alpha-lactalbumin structure, but there were differences in the main-chain conformation of the turn between each deletion mutant and alpha-lactalbumin even if the loop length was the same. For the point mutants, R50G, Q58G, H78G, and G37Q, the main-chain conformations of these substitution residues located in turns adopt a left-handed helical region in the wild-type structure. It is thought that the left-handed non-Gly residue has unfavorable conformational energy compared to the left-handed Gly residue. Q58G was stabilized, but the others had little effect on the stability. The structural analysis revealed that the turns could rearrange the main-chain conformation to accommodate the left-handed non-Gly residues. The present results indicate that turn structures are able to change their main-chain conformations, depending upon the side-chain features of amino acid residues on the turns. Furthermore, stopped-flow GuHCl denaturation experiments on the six mutants were performed. The effects of mutations on unfolding-refolding kinetics were significantly different among the mutant proteins. The deletion/substitutions in turns located in the alpha-domain of human lysozyme affected the refolding rate, indicating the contribution of turn structures to the folding of a globular protein.
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Affiliation(s)
- K Takano
- Institute for Protein Research, Osaka University, Yamadaoka, Suita, Japan
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13
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Arai M, Hamel P, Kanaya E, Inaka K, Miki K, Kikuchi M, Kuwajima K. Effect of an alternative disulfide bond on the structure, stability, and folding of human lysozyme. Biochemistry 2000; 39:3472-9. [PMID: 10727242 DOI: 10.1021/bi9921945] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human lysozyme has four disulfide bonds, one of which, Cys65-Cys81, is included in a long loop of the beta-domain. A cysteine-scanning mutagenesis in which the position of Cys65 was shifted within a continuous segment from positions 61 to 67, with fixed Cys81, has previously shown that only the mutant W64CC65A, which has a nonnative Cys64-Cys81 disulfide, can be correctly folded and secreted by yeast. Here, using the W64CC65A mutant, we investigated the effects of an alternative disulfide bond on the structure, stability, and folding of human lysozyme using circular dichroism (CD) and fluorescence spectroscopy combined with a stopped-flow technique. Although the mutant is expected to have a different main-chain structure from that of the wild-type protein around the loop region, far- and near-UV CD spectra show that the native state of the mutant has tightly packed side chains and secondary structure similar to that of the wild-type. Guanidine hydrochloride-induced equilibrium unfolding transition of the mutant is reversible, showing high stability and cooperativity of folding. In the kinetic folding reaction, both proteins accumulate a similar burst-phase intermediate having pronounced secondary structure within the dead time of the measurement and fold into the native structure by means of a similar folding mechanism. Both the kinetic refolding and unfolding reactions of the mutant protein are faster than those of the wild-type, but the increase in the unfolding rate is larger than that of the refolding rate. The Gibbs' free-energy diagrams obtained from the kinetic analysis suggest that the structure around the loop region in the beta-domain of human lysozyme is formed after the transition state of folding, and thus, the effect of the alternative disulfide bond on the structure, stability, and folding of human lysozyme appears mainly in the native state.
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Affiliation(s)
- M Arai
- Department of Physics, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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14
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Abstract
The endoplasmic reticulum (ER) is a major protein folding compartment for secreted, plasma membrane and organelle proteins. Each of these newly-synthesized polypeptides folds in a deterministic process, affected by the unique conditions that exist in the ER. An understanding of protein folding in the ER is a fundamental biomolecular challenge at two levels. The first level addresses how the amino acid sequence programs that polypeptide to efficiently arrive at a particular fold out of a multitude of alternatives, and how different sequences obtain similar folds. At the second level are the issues introduced by folding not in the cytosol, but in the ER, including the risk of aggregation in a molecularly crowded environment, accommodation of post-translational modifications and the compatibility with subsequent intracellular trafficking. This review discusses both the physicochemical and cell biological constraints of folding, which are the challenges that the ER molecular chaperones help overcome.
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Affiliation(s)
- F J Stevens
- Biosciences Division, Argonne National Lab, IL 60439, USA
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15
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Katakura Y, Ametani A, Totsuka M, Nagafuchi S, Kaminogawa S. Accelerated secretion of mutant beta-lactoglobulin in Saccharomyces cerevisiae resulting from a single amino acid substitution. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1432:302-12. [PMID: 10407152 DOI: 10.1016/s0167-4838(99)00099-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Transformed yeasts producing a mutant form of bovine beta-lactoglobulin (beta-LG), W19Y, in which Trp(19) was replaced with Tyr, were shown to secrete 6 times more than those producing wild type beta-LG. Northern blot analysis suggested that the enhanced level of secretion was not the result of upregulated transcription of W19Y. The ratio of the amount of W19Y secreted into the supernatant to the amount of W19Y remaining inside the cells was much larger than that in the case of wild type beta-LG as shown by immunoblot analysis. A pulse/chase experiment revealed that the speed of secretion of W19Y was significantly accelerated, compared to wild type beta-LG. These results indicated that W19Y was more efficiently and rapidly transported in the course of secretion than wild type beta-LG. Our previous study showed that the DeltaG of unfolding of W19Y in water is 6.9 kcal/mol smaller than that of wild type beta-LG. Furthermore, immunoblot analysis of intracellular beta-LG under non-reducing conditions indicated that W19Y as well as wild type beta-LG maintained a specific folded structure inside the yeast cells, whereas other non-secretable mutant beta-LGs with Phe or Ala at position 19 (W19F and W19A, respectively) did not. These data suggest that low molecular stability and the maintenance of a specific folded structure inside the yeast cells are prerequisites for efficient and rapid secretion. W19Y was more efficiently secreted than wild type beta-LG also in transformed ern1 mutant yeast cells expressing only a basal level of BiP which is considered to function in quality control in the endoplasmic reticulum (ER) by playing an important role in determining the secretion efficiency of secretory proteins. Thus, the reason for the enhanced secretion of W19Y is considered to be that the improved folding ability of W19Y can allow the half-life of the W19Y-BiP complex to become shorter than that of the wild type beta-LG-BiP complex, leading to faster translocation of W19Y into transport vesicles, or that W19Y can fold in a BiP-independent manner in the ER of the yeast cells. Our findings demonstrate that the amount of protein secreted can be improved by alteration of a single amino acid residue crucial for its structure.
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Affiliation(s)
- Y Katakura
- Department of Applied Biological Chemistry, University of Tokyo, Tokyo, Japan.
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16
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Canet D, Sunde M, Last AM, Miranker A, Spencer A, Robinson CV, Dobson CM. Mechanistic studies of the folding of human lysozyme and the origin of amyloidogenic behavior in its disease-related variants. Biochemistry 1999; 38:6419-27. [PMID: 10350460 DOI: 10.1021/bi983037t] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The unfolding and refolding properties of human lysozyme and two amyloidogenic variants (Ile56Thr and Asp67His) have been studied by stopped-flow fluorescence and hydrogen exchange pulse labeling coupled with mass spectrometry. The unfolding of each protein in 5.4 M guanidine hydrochloride (GuHCl) is well described as a two-state process, but the rates of unfolding of the Ile56Thr variant and the Asp67His variant in 5.4 M GuHCl are ca. 30 and 160 times greater, respectively, than that of the wild type. The refolding of all three proteins in 0.54 M GuHCl at pH 5.0 proceeds through persistent intermediates, revealed by multistep kinetics in fluorescence experiments and by the detection of well-defined populations in quenched-flow hydrogen exchange experiments. These findings are consistent with a predominant mechanism for refolding of human lysozyme in which one of the structural domains (the alpha-domain) is formed in two distinct steps and is followed by the folding of the other domain (the beta-domain) prior to the assembly of the two domains to form the native structure. The refolding kinetics of the Asp67His variant are closely similar to those of the wild-type protein, consistent with the location of this mutation in an outer loop of the beta-domain which gains native structure only toward the end of the refolding process. By contrast, the Ile56Thr mutation is located at the base of the beta-domain and is involved in the domain interface. The refolding of the alpha-domain is unaffected by this substitution, but the latter has the effect of dramatically slowing the folding of the beta-domain and the final assembly of the native structure. These studies suggest that the amyloidogenic nature of the lysozyme variants arises from a decrease in the stability of the native fold relative to partially folded intermediates. The origin of this instability is different in the two variants, being caused in one case primarily by a reduction in the folding rate and in the other by an increase in the unfolding rate. In both cases this results in a low population of soluble partially folded species that can aggregate in a slow and controlled manner to form amyloid fibrils.
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Affiliation(s)
- D Canet
- Oxford Centre for Molecular Sciences, University of Oxford, New Chemistry Laboratory, UK
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17
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Takano K, Yamagata Y, Yutani K. A general rule for the relationship between hydrophobic effect and conformational stability of a protein: stability and structure of a series of hydrophobic mutants of human lysozyme. J Mol Biol 1998; 280:749-61. [PMID: 9677301 DOI: 10.1006/jmbi.1998.1906] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To get a general rule for the relationship between hydrophobic effect and conformational stability, five Ile to Val and nine Val to Ala mutants (3SS mutants) from 3SS (C77A/C95A) human lysozyme were constructed. As known from previous studies, the 3SS protein lacking a disulfide bond between Cys77 and Cys95 is destabilized by enthalpic factors, as revealed by a decrease of about 20 kJ/mol in the denaturation Gibbs energy change (DeltaG) value, as compared to the wild-type protein, which has four disulfide bonds. In this study, the stabilities and structures of the 3SS mutants were determined by differential scanning calorimetry and X-ray crystal analysis, respectively, and compared with those of the mutants (4SS mutants) from the wild-type (4SS) protein published previously. The stabilities of all the 3SS mutants, except for V110A-3SS were decreased as compared with that of the 3SS protein, coinciding with the results for the 4SS mutants. The change in the denaturation Gibbs energy change (DeltaDeltaG) values of the 3SS mutants relative to the 3SS protein at the denaturation temperature (49.2 degreesC) of the 3SS protein at pH 2.7 were similar to those of the equivalent 4SS mutants relative to the wild-type at 64.9 degreesC. The Delta DeltaG values of the 3SS mutants correlated with the changes in hydrophobic surface area exposed upon denaturation (Delta DeltaASAHP) for all of the hydrophobic residues when the effects of the secondary structure propensity were considered. This correlation is identical with that previously found for the 4SS mutants. The linear relation between Delta DeltaG and Delta DeltaASAHP for all of the hydrophobic residues with the same slope was found also for the mutants of T4 lysozyme already reported, indicating that this is a general relationship between changes in conformational stability and changes in ASA values of hydrophobic residues due to mutations.
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Affiliation(s)
- K Takano
- Institute for Protein Research, Osaka University, Yamadaoka, Suita, 565-0871, Japan
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18
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Mayo KH, Ilyina E. A folding pathway for betapep-4 peptide 33mer: from unfolded monomers and beta-sheet sandwich dimers to well-structured tetramers. Protein Sci 1998; 7:358-68. [PMID: 9521112 PMCID: PMC2143938 DOI: 10.1002/pro.5560070216] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It was recently reported that a de novo designed peptide 33mer, betapep-4, can form well-structured beta-sheet sandwich tetramers (Ilyina E, Roongta V, Mayo KH, 1997b, Biochemistry 36:5245-5250). For insight into the pathway of betapep-4 folding, the present study investigates the concentration dependence of betapep-4 self-association by using 1H-NMR pulsed-field gradient (PFG)-NMR diffusion measurements, and circular dichroism. Downfield chemically shifted alphaH resonances, found to arise only from the well-structured betapep-4 tetramer state, yield the fraction of tetramer within the oligomer equilibrium distribution. PFG-NMR-derived diffusion coefficients, D, provide a means for deriving the contribution of monomer and other oligomer states to this distribution. These data indicate that tetramer is the highest oligomer state formed, and that inclusion of monomer and dimer states in the oligomer distribution is sufficient to explain the concentration dependence of D values for betapep-4. Equilibrium constants calculated from these distributions [2.5 x 10(5) M(-1) for M-D and 1.2 x 10(4) M(-1) for D-T at 313 K] decrease only slightly, if at all, with decreasing temperature indicating a hydrophobically mediated, entropy-driven association/folding process. Conformational analyses using NMR and CD provide a picture where "random coil" monomers associate to form molten globule-like beta-sheet sandwich dimers that further associate and fold as well-structured tetramers. Betapep-4 folding is thermodynamically linked to self-association. As with folding of single-chain polypeptides, the final folding step to well-structured tetramer betapep-4 is rate limiting.
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Affiliation(s)
- K H Mayo
- Department of Biochemistry, Biomedical Engineering Center, University of Minnesota, Minneapolis 55455, USA.
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19
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Huang XF, Shelness GS. Identification of cysteine pairs within the amino-terminal 5% of apolipoprotein B essential for hepatic lipoprotein assembly and secretion. J Biol Chem 1997; 272:31872-6. [PMID: 9395534 DOI: 10.1074/jbc.272.50.31872] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
There is growing evidence that the amino-terminal globular domain of apolipoprotein B (apoB) is essential for lipoprotein particle formation in the hepatic endoplasmic reticulum. To identify the structural requirements for its function in lipoprotein assembly, cysteine (Cys) pairs required to form the seven disulfide bonds within the amino-terminal 21% of apoB were replaced in groups or individually by serine. Substitution of Cys pairs required for formation of disulfide bonds 1-3 or 4-7 (numbered from amino to carboxyl terminus) completely blocked the secretion of apoB28 in transfected HepG2 cells. To identify the specific disulfide bonds required for secretion, Cys pairs were mutated individually. Substitution of Cys pairs required for disulfide bonds 1, 3, 5, 6, or 7 had little or no impact on apoB28 secretion or buoyant density. In contrast, individual substitution of Cys pair 2 (amino acid residues 51 and 70) or 4 (218 and 234) severely inhibited apoB28 secretion and its capacity to undergo intracellular assembly with lipid. The same assembly and secretion defects were observed when these mutations were expressed as part of apoB50. These studies provide direct evidence that the ability of the internal lipophilic regions of apoB to engage in the recruitment and sequestration of lipid during translation is critically dependent upon a structural configuration contained within or affected by the amino-terminal 5% of the protein.
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Affiliation(s)
- X F Huang
- Department of Comparative Medicine, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157-1040, USA
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20
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Abstract
Due to the detailed knowledge of the three-dimensional structure, chemistry and catalytic mechanism of hen egg white lysozyme, this enzyme has become a major model for the analysis of the folding pathway of globular proteins. Unfolding and folding of lysozyme are reversible processes. Unfolding is a highly cooperative event; under physiological conditions only the native and the unfolded states are stable. Folding of lysozyme involves both a cooperative and a parallel pathway. The complexities in the folding pathway arise from the collapsed state which is formed within a burst-phase in the first milliseconds of folding. In a second, fast folding phase, major parts of the secondary structures both in the alpha-domain and the beta-domain are formed. During the slow folding phase, formation of secondary structure is completed and native tertiary structure is formed in less than 1 second. Folding of reduced lysozyme combines both secondary and tertiary structure organization, as well as formation of four disulphide bonds. Analysis of formation of disulphide bonds showed that there exists a restricted search of structures in the formation of the native conformation and a nucleation in the folding pathway. The transition from a two-disulphide bond intermediate to a three-disulphide bond form appears to be the rate-limiting step in this pathway. Native-like catalytic properties depend on the correct generation of all four disulphide bonds. Folding of both denatured and denatured/reduced lysozyme is characterized by transient folding species possessing structural properties of the molten globule state: high content of secondary structure, no tertiary fold, and the appearance of hydrophobic structures.
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Affiliation(s)
- B Fischer
- IMMUNO AG, Biomedical Research Center, Orth an der Donau, Austria
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21
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Myers JK, Pace CN, Scholtz JM. Denaturant m values and heat capacity changes: relation to changes in accessible surface areas of protein unfolding. Protein Sci 1995; 4:2138-48. [PMID: 8535251 PMCID: PMC2142997 DOI: 10.1002/pro.5560041020] [Citation(s) in RCA: 1439] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Denaturant m values, the dependence of the free energy of unfolding on denaturant concentration, have been collected for a large set of proteins. The m value correlates very strongly with the amount of protein surface exposed to solvent upon unfolding, with linear correlation coefficients of R = 0.84 for urea and R = 0.87 for guanidine hydrochloride. These correlations improve to R = 0.90 when the effect of disulfide bonds on the accessible area of the unfolded protein is included. A similar dependence on accessible surface area has been found previously for the heat capacity change (delta Cp), which is confirmed here for our set of proteins. Denaturant m values and heat capacity changes also correlate well with each other. For proteins that undergo a simple two-state unfolding mechanism, the amount of surface exposed to solvent upon unfolding is a main structural determinant for both m values and delta Cp.
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Affiliation(s)
- J K Myers
- Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843, USA
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22
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Katakura Y, Totsuka M, Ametani A, Kaminogawa S. Tryptophan-19 of beta-lactoglobulin, the only residue completely conserved in the lipocalin superfamily, is not essential for binding retinol, but relevant to stabilizing bound retinol and maintaining its structure. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1207:58-67. [PMID: 8043610 DOI: 10.1016/0167-4838(94)90051-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Residue 19 of tryptophan in bovine beta-lactoglobulin (beta-LG) is the only invariant residue throughout the lipocalin superfamily having two characteristic features: binding ability for small hydrophobic molecules and the unique beta-barrel three-dimensional structure. In this study, we investigated whether this strictly conserved Trp-19 of beta-LG would be indispensable for its structure and function such as maintaining the molecular structure and biological activity of beta-LG. Spectroscopic and enzymatic oxidation experiments on retinol bound to W19Y, in which Tyr was substituted for Trp-19, showed that Trp-19 was not critical for this binding, but was important for stably maintaining the environment surrounding retinol and the bound retinol. An using four anti-beta-LG monoclonal antibodies as probes, revealed a structural change in region 20-29, but not in the reverse region of Trp-19. A guanidine hydrochloride-induced unfolding study showed that the conformational stability of W19Y was greatly reduced by 6.9 kcal/mol compared to that of wild-type beta-LG. These facts indicated that Trp-19 is one of the important residues in correctly maintaining the local structure of beta-LG and stably retaining its overall structure, thereby conserving the bound retinol molecule.
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Affiliation(s)
- Y Katakura
- Department of Agricultural Chemistry, University of Tokyo, Japan
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23
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Equilibrium dissociation and unfolding of nucleoside diphosphate kinase from Dictyostelium discoideum. Role of proline 100 in the stability of the hexameric enzyme. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(20)80724-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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24
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Hayano T, Inaka K, Otsu M, Taniyama Y, Miki K, Matsushima M, Kikuchi M. PDI and glutathione-mediated reduction of the glutathionylated variant of human lysozyme. FEBS Lett 1993; 328:203-8. [PMID: 8344427 DOI: 10.1016/0014-5793(93)80993-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A mutant human lysozyme, designated as C77A-a, in which glutathione is bound to Cys95, has been shown to mimic an intermediate in the formation of a disulfide bond during folding of human (h)-lysozyme. Protein disulfide isomerase (PDI), which is believed to catalyze disulfide bond formation and associated protein folding in the endoplasmic reticulum, attacked the glutathionylated h-lysozyme C77A-a to dissociate the glutathione molecule. Structural analyses showed that the protein is folded and that the structure around the disulfide bond, buried in a hydrophobic core, between the protein and the bound glutathione is fairly rigid. Thioredoxin, which has higher reducing activity of protein disulfides than PDI, catalyzed the reduction with lower efficiency. These results strongly suggest that PDI can catalyze the disulfide formation in intermediates with compact structure like the native states in the later step of in vivo protein folding.
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Affiliation(s)
- T Hayano
- Protein Engineering Research Institute, Osaka, Japan
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25
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Omura F, Otsu M, Kikuchi M. Accelerated secretion of human lysozyme with a disulfide bond mutation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 205:551-9. [PMID: 1572356 DOI: 10.1111/j.1432-1033.1992.tb16812.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The mutant human lysozyme, [Ala77, Ala95]lysozyme, in which the disulfide bond Cys77-Cys95 is eliminated, is known to exhibit increased secretion in yeast, compared to wild-type human lysozyme [Taniyama, Y., Yamamoto, Y., Nakao, M., Kikuchi, M. & Ikehara, M. (1988) Biochem. Biophys. Res. Commun. 152, 962-967]. To investigate this phenomenon, mammalian cells were used to analyze the secretion kinetics of [Ala77, Ala95]lysozyme and wild-type human lysozyme. The secretion rate of [Ala77, Ala95]lysozyme during the 150-min chase period was significantly accelerated [half-life (t1/2) = 29 min] compared to that of wild-type human lysozyme (t1/2 = 83 min), when expressed at the same levels within the cells. In contrast, after the 150-min chase, the rates of disappearance of both wild-type and mutant human lysozymes within the cells were similar, and considerably slower (t1/2 = 220 min), respectively. The remaining intracellular wild-type human lysozyme was localized mainly in the endoplasmic reticulum, whereas accelerated transport of the [Ala77, Ala95]lysozyme mutant protein from the endoplasmic reticulum to the Golgi apparatus was observed. Also in yeast cells, similar secretion kinetics and the differences in t1/2 for wild-type and mutant human lysozymes during the early chase period were observed. The two-phase kinetics of disappearance of intracellular human lysozymes suggest that only a proportion of the proteins becomes secretion competent soon after synthesis and is completely secreted during the early chase period, whereas others enter the distinct, slow pathways of intracellular transport and/or degradation. Increased secretion of [Ala77, Ala95]lysozyme is possibly due to enhanced competence for secretion acquired in the endoplasmic reticulum at the early stage of transport events, which is closely connected with the removal of a disulfide bond.
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Affiliation(s)
- F Omura
- Protein Engineering Research Institute, Osaka, Japan
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