1
|
Michalska K, Kowiel M, Bigelow L, Endres M, Gilski M, Jaskolski M, Joachimiak A. 3D domain swapping in the TIM barrel of the α subunit of Streptococcus pneumoniae tryptophan synthase. Acta Crystallogr D Struct Biol 2020; 76:166-175. [PMID: 32038047 PMCID: PMC7008512 DOI: 10.1107/s2059798320000212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 01/08/2020] [Indexed: 02/10/2023] Open
Abstract
Tryptophan synthase catalyzes the last two steps of tryptophan biosynthesis in plants, fungi and bacteria. It consists of two protein chains, designated α and β, encoded by trpA and trpB genes, that function as an αββα complex. Structural and functional features of tryptophan synthase have been extensively studied, explaining the roles of individual residues in the two active sites in catalysis and allosteric regulation. TrpA serves as a model for protein-folding studies. In 1969, Jackson and Yanofsky observed that the typically monomeric TrpA forms a small population of dimers. Dimerization was postulated to take place through an exchange of structural elements of the monomeric chains, a phenomenon later termed 3D domain swapping. The structural details of the TrpA dimer have remained unknown. Here, the crystal structure of the Streptococcus pneumoniae TrpA homodimer is reported, demonstrating 3D domain swapping in a TIM-barrel fold for the first time. The N-terminal domain comprising the H0-S1-H1-S2 elements is exchanged, while the hinge region corresponds to loop L2 linking strand S2 to helix H2'. The structural elements S2 and L2 carry the catalytic residues Glu52 and Asp63. As the S2 element is part of the swapped domain, the architecture of the catalytic apparatus in the dimer is recreated from two protein chains. The homodimer interface overlaps with the α-β interface of the tryptophan synthase αββα heterotetramer, suggesting that the 3D domain-swapped dimer cannot form a complex with the β subunit. In the crystal, the dimers assemble into a decamer comprising two pentameric rings.
Collapse
Affiliation(s)
- Karolina Michalska
- Midwest Center for Structural Genomics, X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL 60637, USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Marcin Kowiel
- Center for Biocrystallographic Research, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
| | - Lance Bigelow
- Midwest Center for Structural Genomics, X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Michael Endres
- Midwest Center for Structural Genomics, X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Miroslaw Gilski
- Center for Biocrystallographic Research, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
- Department of Crystallography, Faculty of Chemistry, A. Mickiewicz University, Poznan, Poland
| | - Mariusz Jaskolski
- Center for Biocrystallographic Research, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
- Department of Crystallography, Faculty of Chemistry, A. Mickiewicz University, Poznan, Poland
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics, X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
- Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL 60637, USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| |
Collapse
|
2
|
|
3
|
Schneider WP, Nichols BP, Yanofsky C. Procedure for production of hybrid genes and proteins and its use in assessing significance of amino acid differences in homologous tryptophan synthetase alpha polypeptides. Proc Natl Acad Sci U S A 1981; 78:2169-73. [PMID: 7017727 PMCID: PMC319305 DOI: 10.1073/pnas.78.4.2169] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Hybrid tryptophan synthetase alpha and beta polypeptides were produced by genetic recombination between the trpB--trpA regions of Escherichia coli and Salmonella typhimurium contained on compatible, multicopy plasmids. Intragenic recombination was decreased but still evident in recA cells. Genetic exchange occurred at many sites within trpA, but every recombinant gene produced a functional alpha polypeptide despite many amino acid differences from one or the other of the parental polypeptides. The five hybrid tryptophan synthetase alpha subunits examined resembled the parental polypeptides in catalytic function but differed in thermostability. The stability differences suggest that, as amino acid changes occurred in these proteins during the course of evolution, subsequent changes were limited to those that would allow retention of a desired protein conformation.
Collapse
|
4
|
Crawford IP, Nichols BP, Yanofsky C. Nucleotide sequence of the trpB gene in Escherichia coli and Salmonella typhimurium. J Mol Biol 1980; 142:489-502. [PMID: 7007651 DOI: 10.1016/0022-2836(80)90259-4] [Citation(s) in RCA: 129] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
|
5
|
Nichols BP, Miozzari GF, van Cleemput M, Bennett GN, Yanofsky C. Nucleotide sequences of the trpG regions of Escherichia coli, Shigella dysenteriae, Salmonella typhimurium and Serratia marcescens. J Mol Biol 1980; 142:503-17. [PMID: 7007652 DOI: 10.1016/0022-2836(80)90260-0] [Citation(s) in RCA: 105] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
|
6
|
Nichols BP, Yanofsky C. Nucleotide sequences of trpA of Salmonella typhimurium and Escherichia coli: an evolutionary comparison. Proc Natl Acad Sci U S A 1979; 76:5244-8. [PMID: 388433 PMCID: PMC413117 DOI: 10.1073/pnas.76.10.5244] [Citation(s) in RCA: 121] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The complete nucleotide sequences of trpA of Salmonella typhimurium and Escherichia coli were determined. The nucleotide sequences are 24.8% divergent, compared with amino acid sequence divergence of 14.9%. Over half of the codons of each gene contain synonymous nucleotide changes. The pattern of synonymous nucleotide changes is consistent with the interpretation that such changes result from random mutational events. We do not find any evidence indicating that codon selection or RNA structure is of major selective value. We conclude that polypeptide function is the primary basis of selection in trpA and that most synonymous codon changes are selectively neutral.
Collapse
|
7
|
Brennan EF, Rocha V. Trypsin peptide patterns of tryptophan synthase beta2 protein among four species of the Enterobacteriaceae. J Bacteriol 1978; 136:790-4. [PMID: 361723 PMCID: PMC218606 DOI: 10.1128/jb.136.2.790-794.1978] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The tryptophan synthase beta 2 protein (EC 4.2.1.20) of Escherichia coli, Enterobacter aerogenes, Serratia marcescens, and Erwinia carotovora was purified and compared. Two-dimensional total peptide patterns for each of the four beta2 proteins obtained after digestion with trypsin showed that approximately three quarters of the total peptides are common to all four peptides. Examination of only arginine-containing peptides showed that approximately half of these peptides are common. From a comparative standpoint, the data provide evidence that the primary structure of beta 2 proteins is relatively similar, indicating that the trpB cistron is evolutionarily conserved in the enteric bacteria group.
Collapse
|
8
|
Miozzari G, Yanofsky C. Naturally occurring promoter down mutation: nucleotide sequence of the trp promoter/operator/leader region of Shigella dysenteriae 16. Proc Natl Acad Sci U S A 1978; 75:5580-4. [PMID: 364484 PMCID: PMC393010 DOI: 10.1073/pnas.75.11.5580] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The promoter/operator/leader region of the trp operon of Shigella dysenteriae 16 has single base pair differences from the corresponding region of Escherichia coli at positions -24 and -13. The difference at -13 was shown to be responsible for the 90% reduction in promoter function characteristic of the trp operon of S. dysenteriae. The base pair difference at position -13 also renders the operator partially constitutive. This allows the organism to maintain relatively high repressed levels of the trp enzymes and increases the relative importance of attenuation as a transcription control mechanism. These findings and the earlier observation that the trpE protein of S. dysenteriae is only slightly active explain the low in vivo expression of the trp operon of this organism. Nutritional studies suggest that operons involved in other amino acid biosynthetic pathways in S. dysenteriae 16 may be similarly partially inactivated.
Collapse
|
9
|
Reyes GR, Rocha V. Immunochemical comparison of phosphoribosylanthranilate isomerase-indoleglycerol phosphate synthetase among the Enterobacteriaceae. J Bacteriol 1977; 129:1448-56. [PMID: 403178 PMCID: PMC235122 DOI: 10.1128/jb.129.3.1448-1456.1977] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The bifunctional enzyme of the tryptophan operon, phosphoribosylanthranilate isomerase-indoleglycerol phosphate synthetase (PRAI-InGPS;EC 4.1.1.48), was characterized by an immunochemical study of six representative members of the Enterobacteriaceae: Escherichia coli, Salmonella typhimurium, Enterobacter aerogenes, Serratia marcescens, Erwinia carotovora, and Proteus vulgaris. PRAI-InGPS was purified from E. coli, and antisera were prepared in rabbits. These antisera were utilized in quantitative microcomplement fixation allowing for a comparison of the overall antigenic surface structure of the various homologous enzymes. These data showed E. coli PRAI-InGPS and S. marcescens and E. carotovora PRAI-InGPS (taken as a group) to have an index of dissimilarity of approximately 10, whereas the other organisms had values intermediate. In addition, antiserum to E. coli tryptophan synthetase beta2 subunit was used in microcomplement fixation to extend the previous comparison of this subunit (Rocha, Crawford, and Mills, 1972) to E. carotovora and P. vulgaris. Indexes of dissimilarity for E. coli compared to P. vulgaris of E. carotovora were 1.0 and 1.7, respectively. Agar immunodiffusion using PRAI-Ingps antisera showed significant cross-reaction among E. coli, E. aerogenes, S. typhimurium, and P. vulgaris whereas the enzymes from S. marcescens and E. carotovora cross-reacted to a lesser extent, with the latter reaction being quite weak. Comparative enzyme neutralization using E. coli PRAI-InGPS antisera showed significant cross-reactions among the enzymes in that all were neutralized at least 25%. The data taken together indicate that the trpC gene products in the Enterobacteriaceae are a homologous group of proteins, that the genetic divergene of the trpC gene is basically the same as the trpA gene, and that both are less conserved than the trpB gene. Furthermore, the PRAI-InGPS, enzyme active site appears to represent a more evolutionarily conserved region of the protein. These findings indicate that, with respect to PRAI-InGPS, similarity to E. coli among the organisms examined is in the following order: (E. aerogenes, S. typhimurium, P. vulgaris) greater than (S. marcescens, E. carotovora).
Collapse
|
10
|
Creighton TE. The functional significance of the evolutionary divergence between the tryptophan operons of Escherichia coli and Salmonella typhimurium. J Mol Evol 1974; 4:121-37. [PMID: 4619891 DOI: 10.1007/bf01732018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
11
|
Dicamelli RF, Balbinder E, Lebowitz J. Pressure effects on the association of the and 2 subunits of tryptophan synthetase from Escherichia coli and Salmonella typhimurium. Arch Biochem Biophys 1973; 155:315-24. [PMID: 4574541 DOI: 10.1016/0003-9861(73)90120-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
12
|
Abstract
An immunological approach has been used for the study of alkaline phosphatase evolution in bacteria of the family Enterobacteriaceae. Antisera were prepared against alkaline phosphatase from Escherichia coli and Klebsiella aerogenes and tested against the unpurified alkaline phosphatases of 32 strains of enterobacteria by double diffusion and quantitative micro-complement fixation. The immunological relationships detected among the alkaline phosphatases of enterobacteria agree approximately with those reported for five other enzymes, as well as with the tryptic peptide pattern similarities found for two other enzymes, and with the relationships detected by interspecific deoxyribonucleic acid hybridization tests.
Collapse
|
13
|
Abstract
A temperature-sensitive mutant of Escherichia coli is described that at the restrictive temperature has lost the ability to plasmolyze. The mutation is located near pyrF.
Collapse
|
14
|
Li SL, Yanofsky C. Amino Acid Sequences of Fifty Residues from the Amino Termini of the Tryptophan Synthetase α Chains of Several Enterobacteria. J Biol Chem 1972. [DOI: 10.1016/s0021-9258(19)45611-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
15
|
Abstract
The two protein components of Pseudomonas putida tryptophan synthetase have been purified to homogeneity. Although there is general similarity between the Pseudomonas enzyme and that of the enteric bacteria, many differences were found. Components from Escherichia coli and P. putida do not stimulate each other enzymatically, and the enzymes differ in their response to monovalent cations. Serine deamination occurs best with the intact enzyme of P. putida, not with the beta(2) subunit alone as in E. coli. The amino acid compositions of the alpha subunits differ appreciably. These findings extend earlier studies showing differences between enteric organisms and pseudomonads in the regulation and genetic organization of the enzymes of the tryptophan pathway.
Collapse
|
16
|
Abstract
There is 50% identity in the sequences of the first 50 residues of the alpha chains of Escherichia coli and Pseudomonas putida. No deletions or additions of residues are found in this region, except for the N-terminal methionine residue which is missing in the polypeptide isolated from P. putida. Most of the residues which differ are chemically dissimilar, and half of them are specified by codons which differ by more than a single base. The two residues known by mutational analysis to be essential for catalysis in E. coli are conserved in P. putida. The potential taxonomic usefulness of information of this sort is analyzed.
Collapse
|
17
|
Sanderson KE. Genetics of the Enterobacteriaceae. A. Genetic homology in the Enterobacteriaceae. ADVANCES IN GENETICS 1971; 16:35-51. [PMID: 4947111 DOI: 10.1016/s0065-2660(08)60353-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
18
|
Sakaguchi K. The similarity of tryptophan synthetases of Anabaena variabilis and Chlorella ellipsoidea with that of bacteria. BIOCHIMICA ET BIOPHYSICA ACTA 1970; 220:580-93. [PMID: 4993405 DOI: 10.1016/0005-2744(70)90288-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
19
|
McQuade JF, Creighton TE. Purification and comparison of the N-(5'-phosphoribosyl)anthranilic acid isomerase-indole-3-glycerol phosphate synthetase of tryptophan biosynthesis from three species of Enterobacteriaceae. EUROPEAN JOURNAL OF BIOCHEMISTRY 1970; 16:199-207. [PMID: 4919415 DOI: 10.1111/j.1432-1033.1970.tb01072.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
20
|
Abstract
Coordination of gene expression in the lac operon was compared in Escherichia coli and Salmonella typhimurium as an approach to detecting possible differences in protein synthesis or membrane structure between organisms. Either a wild-type F' lac pro(AB) episome or the same episome with a polar mutation in one of the lac genes was introduced into pro(-) derivatives of the two strains of bacteria. Activity assays showed that the beta-galactosidase levels were only slightly lower in the S. typhimurium cells than in E. coli cells, whereas the transacetylase levels were significantly higher in S. typhimurium for all of the lac markers tested. Galactoside transport activities were always comparable in the two strains of bacteria; this latter result indicates that the cell envelopes of E. coli and S. typhimurium do not differ sufficiently to affect the membrane-associated lac transport system. It was found, however, that the specific transport activity is very sensitive to culture age in both bacteria, and decreases rapidly in cultures past the mid-exponential phase of growth.
Collapse
|
21
|
Restoration of Enzymic Activity by Complementation in Vitro between Mutant α Subunits of Tryptophan Synthetase and between Mutant Subunits and Fragments of the α Subunit. J Biol Chem 1969. [DOI: 10.1016/s0021-9258(18)93660-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
|
22
|
|
23
|
Murphy TM, Mills SE. Immunochemical and enzymatic comparisons of the tryptophan synthase alpha subunits from five species of Enterobacteriaceae. J Bacteriol 1969; 97:1310-20. [PMID: 4887511 PMCID: PMC249849 DOI: 10.1128/jb.97.3.1310-1320.1969] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The reactive surface structures of alpha subunits of tryptophan synthase from Escherichia coli, Shigella dysenteriae, Salmonella typhimurium, Aerobacter aerogenes, and Serratia marcescens were compared by measuring (i) their reactivities in micro-complement-fixation assays with antibodies directed specifically to E. coli wild-type alpha subunit, (ii) their reactivities in enzyme neutralization assays with the same antibodies, and (iii) their binding affinities for tryptophan synthase beta(2) subunits. The enzymes from the four heterologous species cross-reacted in the microcomplement-fixation assays with the anti-E. coli alpha subunit antibodies, each to a different degree. However, neutralization titers of the antibodies reacting with the various alpha subunits were comparatively similar, and the beta(2) subunit-binding and -stimulating abilities of the alpha subunits were even more closely alike. The results suggested that the tertiary structure of the beta(2) subunit-binding site of the alpha subunit has been conserved, relative to the rest of the molecule, during the evolutionary divergence of the species of Enterobacteriaceae.
Collapse
|
24
|
Murphy TM, Mills SE. Immunochemical comparisons of mutant and wild-type alpha-subunits of tryptophan synthetase. Arch Biochem Biophys 1968; 127:7-16. [PMID: 4971455 DOI: 10.1016/0003-9861(68)90194-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
25
|
Ino I, Demerec M. Enteric hybrids. II. S. typhimurium-E. coli hybrids for the trp-cysB-pyrF region. Genetics 1968; 59:167-76. [PMID: 4883171 PMCID: PMC1211939 DOI: 10.1093/genetics/59.2.167] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
|
26
|
Bowman JE, Brubaker RR, Frischer H, Carson PE. Characterization of enterobacteria by starch-gel electrophoresis of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase. J Bacteriol 1967; 94:544-51. [PMID: 5340676 PMCID: PMC251920 DOI: 10.1128/jb.94.3.544-551.1967] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Specific activities and electrophoretic mobilities of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase were determined in 38 isolates of the family Enterobacteriaceae and in 10 isolates of the related Pasteurella. The deficiency of glucose-6-phosphate dehydrogenase in P. pestis was verified. Enzymes obtained from different strains of the same species exhibited an unexpected degree of heterogeneity. For example, 8 and 11 apparent variants of glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase, respectively, were found in 14 strains of Escherichia coli. Although similar frequencies of heterogeneity were noted in 7 strains of P. pseudotuberculosis, 5 species of Shigella, and 8 species of Salmonella, differences in mobility were generally small in comparison with those observed between strains of E. coli. Values obtained for the pasteurellae, shigellae, and salmonellae, thus fell within narrow ranges that may prove typical for the genera. However, most of these ranges, as well as many values observed for single species of other genera, were overlapped by the wide range recorded for E. coli. The significance of this observation was discussed with respect to the relative age and taxonomic position of the organisms in question. The method could be used to distinguish between most wild-type strains of the same species and should thus facilitate investigations of genetic transfer and epidemiology.
Collapse
|
27
|
Somerville RL. Tryptophan operon of Escherichia coli: regulatory behavior in Salmonella typhimurium cytoplasm. Science 1966; 154:1585-7. [PMID: 5332550 DOI: 10.1126/science.154.3756.1585] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Hybrids hemizygous for the tryptophan genes were prepared by episomal transfer of an Escherichia coli element into Salmonella typhimurium. Regulation of enzyme production by hybrids carrying wild-type E. coli genes in response to changes in the growth medium occurs in precisely the same manner as in haploid E. coli wild type. Mutant alleles of the anthranilate synhetase gene of E. coli which prevent derepression in E. coli function identically in S. typhimurium. At least one Salmonella tryptophan regulatory gene unlinked to the structural genes is known. Any dijferences which may exist between the tryptophan regulatory genes of E. coli and Salmonella have little effect on the regulation of enzyme formation in hybrids.
Collapse
|