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Fang Y, Gu Y, Li L, Zhu L, Qian J, Zhao C, Xu L, Wei W, Du Y, Yuan N, Zhang S, Yuan Y, Xu Y, Jiang C, Wang J. Loss of Atg7 causes chaotic nucleosome assembly of mouse bone marrow CD11b +Ly6G - myeloid cells. Aging (Albany NY) 2020; 12:25673-25683. [PMID: 33232280 PMCID: PMC7803583 DOI: 10.18632/aging.104176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/15/2020] [Indexed: 12/13/2022]
Abstract
Atg7, a critical component of autophagy machinery, is essential for counteracting hematopoietic aging. However, the non-autophagic role of Atg7 on hematopoietic cells remains fundamentally unclear. In this study, we found that loss of Atg7, but not Atg5, another autophagy-essential gene, in the hematopoietic system reduces CD11b myeloid cellularity including CD11b+Ly6G+ and CD11b+Ly6G- populations in mouse bone marrow. Surprisingly, Atg7 deletion causes abnormally accumulated histone H3.1 to be overwhelmingly trapped in the cytoplasm in the CD11b+Ly6G-, but not the CD11b+Ly6G+ compartment. RNA profiling revealed extensively chaotic expression of the genes required in nucleosome assembly. Functional assays further indicated upregulated aging markers in the CD11b+Ly6G- population. Therefore, our study suggests that Atg7 is essential for maintaining proper nucleosome assembly and limiting aging in the bone marrow CD11b+Ly6G- population.
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Affiliation(s)
- Yixuan Fang
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China.,National Clinical Research Center for Hematologic Diseases, Collaborative Innovation Center of Hematology, Jiangsu Institute of Hematology, Institute of Blood and Marrow Transplantation, Department of Hematology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China.,Department of Hematopoietic Engineering, Susky Life SciTech (Suzhou) Co. Ltd., Suzhou 215124, China.,State Key Laboratory of Radiation Medicine and Radioprotection, Soochow University School of Medicine, Suzhou 215123, China
| | - Yue Gu
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China.,National Clinical Research Center for Hematologic Diseases, Collaborative Innovation Center of Hematology, Jiangsu Institute of Hematology, Institute of Blood and Marrow Transplantation, Department of Hematology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Lei Li
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China.,National Clinical Research Center for Hematologic Diseases, Collaborative Innovation Center of Hematology, Jiangsu Institute of Hematology, Institute of Blood and Marrow Transplantation, Department of Hematology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Lingjiang Zhu
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China.,National Clinical Research Center for Hematologic Diseases, Collaborative Innovation Center of Hematology, Jiangsu Institute of Hematology, Institute of Blood and Marrow Transplantation, Department of Hematology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Jiawei Qian
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China
| | - Chen Zhao
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China.,National Clinical Research Center for Hematologic Diseases, Collaborative Innovation Center of Hematology, Jiangsu Institute of Hematology, Institute of Blood and Marrow Transplantation, Department of Hematology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Li Xu
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China.,National Clinical Research Center for Hematologic Diseases, Collaborative Innovation Center of Hematology, Jiangsu Institute of Hematology, Institute of Blood and Marrow Transplantation, Department of Hematology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Wen Wei
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China.,National Clinical Research Center for Hematologic Diseases, Collaborative Innovation Center of Hematology, Jiangsu Institute of Hematology, Institute of Blood and Marrow Transplantation, Department of Hematology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Yanhua Du
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, the School of Life Sciences and Technology, Shanghai Key Laboratory of Signaling and Disease Research, Tongji University, Shanghai 200092, China
| | - Na Yuan
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China.,National Clinical Research Center for Hematologic Diseases, Collaborative Innovation Center of Hematology, Jiangsu Institute of Hematology, Institute of Blood and Marrow Transplantation, Department of Hematology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China.,Department of Hematopoietic Engineering, Susky Life SciTech (Suzhou) Co. Ltd., Suzhou 215124, China.,State Key Laboratory of Radiation Medicine and Radioprotection, Soochow University School of Medicine, Suzhou 215123, China
| | - Suping Zhang
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China.,National Clinical Research Center for Hematologic Diseases, Collaborative Innovation Center of Hematology, Jiangsu Institute of Hematology, Institute of Blood and Marrow Transplantation, Department of Hematology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China.,Department of Hematopoietic Engineering, Susky Life SciTech (Suzhou) Co. Ltd., Suzhou 215124, China.,State Key Laboratory of Radiation Medicine and Radioprotection, Soochow University School of Medicine, Suzhou 215123, China
| | - Ye Yuan
- Department of Orthopaedics, the Second Affiliated Hospital of Soochow University, Osteoporosis Institute of Soochow University, Suzhou 215004, China
| | - Youjia Xu
- Department of Orthopaedics, the Second Affiliated Hospital of Soochow University, Osteoporosis Institute of Soochow University, Suzhou 215004, China
| | - Cizhong Jiang
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, the School of Life Sciences and Technology, Shanghai Key Laboratory of Signaling and Disease Research, Tongji University, Shanghai 200092, China
| | - Jianrong Wang
- Hematology Center of Cyrus Tang Medical Institute, Soochow University School of Medicine, Suzhou 215123, China.,National Clinical Research Center for Hematologic Diseases, Collaborative Innovation Center of Hematology, Jiangsu Institute of Hematology, Institute of Blood and Marrow Transplantation, Department of Hematology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China.,Department of Hematopoietic Engineering, Susky Life SciTech (Suzhou) Co. Ltd., Suzhou 215124, China.,State Key Laboratory of Radiation Medicine and Radioprotection, Soochow University School of Medicine, Suzhou 215123, China
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Mills-Davies N, Butler D, Norton E, Thompson D, Sarwar M, Guo J, Gill R, Azim N, Coker A, Wood SP, Erskine PT, Coates L, Cooper JB, Rashid N, Akhtar M, Shoolingin-Jordan PM. Structural studies of substrate and product complexes of 5-aminolaevulinic acid dehydratase from humans,Escherichia coliand the hyperthermophilePyrobaculum calidifontis. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2017; 73:9-21. [DOI: 10.1107/s2059798316019525] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 12/06/2016] [Indexed: 11/11/2022]
Abstract
A number of X-ray analyses of an enzyme involved in a key early stage of tetrapyrrole biosynthesis are reported. Two structures of human 5-aminolaevulinate dehydratase (ALAD), native and recombinant, have been determined at 2.8 Å resolution, showing that the enzyme adopts an octameric quaternary structure in accord with previously published analyses of the enzyme from a range of other species. However, this is in contrast to the finding that a disease-related F12L mutant of the human enzyme uniquely forms hexamers [Breiniget al.(2003),Nature Struct. Biol.10, 757–763]. Monomers of all ALADs adopt the TIM-barrel fold; the subunit conformation that assembles into the octamer includes the N-terminal tail of one monomer curled around the (α/β)8barrel of a neighbouring monomer. Both crystal forms of the human enzyme possess two monomers per asymmetric unit, termedAandB. In the native enzyme there are a number of distinct structural differences between theAandBmonomers, with the latter exhibiting greater disorder in a number of loop regions and in the active site. In contrast, the second monomer of the recombinant enzyme appears to be better defined and the active site of both monomers clearly possesses a zinc ion which is bound by three conserved cysteine residues. In native human ALAD, theAmonomer also has a ligand resembling the substrate ALA which is covalently bound by a Schiff base to one of the active-site lysines (Lys252) and is held in place by an ordered active-site loop. In contrast, these features of the active-site structure are disordered or absent in theBsubunit of the native human enzyme. The octameric structure of the zinc-dependent ALAD from the hyperthermophilePyrobaculum calidifontisis also reported at a somewhat lower resolution of 3.5 Å. Finally, the details are presented of a high-resolution structure of theEscherichia coliALAD enzyme co-crystallized with a noncovalently bound moiety of the product, porphobilinogen (PBG). This structure reveals that the pyrrole side-chain amino group is datively bound to the active-site zinc ion and that the PBG carboxylates interact with the enzymeviahydrogen bonds and salt bridges with invariant residues. A number of hydrogen-bond interactions that were previously observed in the structure of yeast ALAD with a cyclic intermediate resembling the product PBG appear to be weaker in the new structure, suggesting that these interactions are only optimal in the transition state.
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Abstract
Porphobilinogen synthase (PBGS), also known as 5-aminolevulinate dehydratase, is an essential enzyme in the biosynthesis of all tetrapyrroles, which function in respiration, photosynthesis, and methanogenesis. Throughout evolution, PBGS adapted to a diversity of cellular niches and evolved to use an unusual variety of metal ions both for catalytic function and to control protein multimerization. With regard to the active site, some PBGSs require Zn2+; a subset of those, including human PBGS, contain a constellation of cysteine residues that acts as a sink for the environmental toxin Pb2+. PBGSs that do not require the soft metal ion Zn2+ at the active site instead are suspected of using the hard metal Mg2+. The most unexpected property of the PBGS family of enzymes is a dissociative allosteric mechanism that utilizes an equilibrium of architecturally and functionally distinct protein assemblies. The high-activity assembly is an octamer in which intersubunit interactions modulate active-site lid motion. This octamer can dissociate to dimer, the dimer can undergo a hinge twist, and the twisted dimer can assemble to a low-activity hexamer. The hexamer does not have the intersubunit interactions required to stabilize a closed conformation of the active site lid. PBGS active site chemistry benefits from a closed lid because porphobilinogen biosynthesis includes Schiff base formation, which requires deprotonated lysine amino groups. N-terminal and C-terminal sequence extensions dictate whether a specific species of PBGS can sample the hexameric assembly. The bulk of species (nearly all except animals and yeasts) use Mg2+ as an allosteric activator. Mg2+ functions allosterically by binding to an intersubunit interface that is present in the octamer but absent in the hexamer. This conformational selection allosteric mechanism is purported to be essential to avoid the untimely accumulation of phototoxic chlorophyll precursors in plants. For those PBGSs that do not use the allosteric Mg2+, there is a spatially equivalent arginine-derived guanidium group. Deprotonation of this residue promotes formation of the hexamer and accounts for the basic arm of the bell-shaped pH vs activity profile of human PBGS. A human inborn error of metabolism known as ALAD porphyria is attributed to PBGS variants that favor the hexameric assembly. The existence of one such variant, F12L, which dramatically stabilizes the human PBGS hexamer, allowed crystal structure determination for the hexamer. Without this crystal structure and octameric PBGS structures containing the allosteric Mg2+, it would have been difficult to decipher the structural basis for PBGS allostery. The requirement for multimer dissociation as an intermediate step in PBGS allostery was established by monitoring subunit disproportionation during the turnover-dependent transition of heteromeric PBGS (comprised of human wild type and F12L) from hexamer to octamer. One outcome of these studies was the definition of the dissociative morpheein model of protein allostery. The phylogenetically variable time scales for PBGS multimer interconversion result in atypical kinetic and biophysical behaviors. These behaviors can serve to identify other proteins that use the morpheein model of protein allostery.
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Affiliation(s)
- Eileen K. Jaffe
- Fox Chase Cancer Center, Temple University Health System, 333 Cottman Avenue, Philadelphia, Pennsylvania 19111, United States
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Jaffe EK, Stith L. ALAD porphyria is a conformational disease. Am J Hum Genet 2007; 80:329-37. [PMID: 17236137 PMCID: PMC1785348 DOI: 10.1086/511444] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Accepted: 12/04/2006] [Indexed: 11/03/2022] Open
Abstract
ALAD porphyria is a rare porphyric disorder, with five documented compound heterozygous patients, and it is caused by a profound lack of porphobilinogen synthase (PBGS) activity. PBGS, also called "delta-aminolevulinate dehydratase," is encoded by the ALAD gene and catalyzes the second step in the biosynthesis of heme. ALAD porphyria is a recessive disorder; there are two common variant ALAD alleles, which encode K59 and N59, and eight known porphyria-associated ALAD mutations, which encode F12L, E89K, C132R, G133R, V153M, R240W, A274T, and V275M. Human PBGS exists as an equilibrium of functionally distinct quaternary structure assemblies, known as "morpheeins," in which one functional homo-oligomer can dissociate, change conformation, and reassociate into a different oligomer. In the case of human PBGS, the two assemblies are a high-activity octamer and a low-activity hexamer. The current study quantifies the morpheein forms of human PBGS for the common and porphyria-associated variants. Heterologous expression in Escherichia coli, followed by separation of the octameric and hexameric assemblies on an ion-exchange column, showed that the percentage of hexamer for F12L (100%), R240W (80%), G133R (48%), C132R (36%), E89K (31%), and A274T (14%) was appreciably larger than for the wild-type proteins K59 and N59 (0% and 3%, respectively). All eight porphyria-associated variants, including V153M and V275M, showed an increased propensity to form the hexamer, according to a kinetic analysis. Thus, all porphyria-associated human PBGS variants are found to shift the morpheein equilibrium for PBGS toward the less active hexamer. We propose that the disequilibrium of morpheein assemblies broadens the definition of conformational diseases beyond the prion disorders and that ALAD porphyria is the first example of a morpheein-based conformational disease.
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Whitworth KM, Agca C, Kim JG, Patel RV, Springer GK, Bivens NJ, Forrester LJ, Mathialagan N, Green JA, Prather RS. Transcriptional Profiling of Pig Embryogenesis by Using a 15-K Member Unigene Set Specific for Pig Reproductive Tissues and Embryos1. Biol Reprod 2005; 72:1437-51. [PMID: 15703372 DOI: 10.1095/biolreprod.104.037952] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Differential mRNA expression patterns were evaluated between germinal vesicle oocytes (pgvo), four-cell (p4civv), blastocyst (pblivv), and in vitro-produced four-cell (p4civp) and in vitro-produced blastocyst (pblivp) stage embryos to determine key transcripts responsible for early embryonic development in the pig. Five comparisons were made: pgvo to p4civv, p4civv to pblivv, pgvo to pblivv, p4civv to p4civp, and pblivv to pblivp. ANOVA (P < 0.05) was performed with the Benjamini and Hochberg false-discovery-rate multiple correction test on each comparison. A comparison of pgvo to p4civv, p4civv to pblivv, and pgvo to pblivv resulted in 3214, 1989, and 4528 differentially detected cDNAs, respectively. Real-time PCR analysis on seven transcripts showed an identical pattern of changes in expression as observed on the microarrays, while one transcript deviated at a single cell stage. There were 1409 and 1696 differentially detected cDNAs between the in vitro- and in vivo-produced embryos at the four-cell and blastocyst stages, respectively, without the Benjamini and Hochberg false-discovery-rate multiple correction test. Real-time polymerase chain reaction (PCR) analysis on four genes at the four-cell stage showed an identical pattern of gene expression as found on the microarrays. Real-time PCR analysis on four of five genes at the blastocyst stage showed an identical pattern of gene expression as found on the microarrays. Thus, only 1 of the 39 comparisons of the pattern of gene expression exhibited a major deviation between the microarray and the real-time PCR. These results illustrate the complex mechanisms involved in pig early embryonic development.
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Affiliation(s)
- K M Whitworth
- Department of Animal Science, University of Missouri-Columbia, Missouri 65211, USA
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