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Thapliyal C, Mishra R. The Chaperone-Active State of HdeB at pH 4 Arises from Its Conformational Rearrangement and Enhanced Stability Instead of Surface Hydrophobicity. Biochemistry 2024; 63:1147-1161. [PMID: 38640496 DOI: 10.1021/acs.biochem.4c00132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2024]
Abstract
HdeA and HdeB are dimeric ATP-independent acid-stress chaperones, which protect the periplasmic proteins of enteric bacteria at pH 2.0 and 4.0, respectively, during their passage through the acidic environment of the mammalian stomach. Despite being structurally similar, they exhibit distinct functional pH optima and conformational prerequisite for their chaperone action. HdeA undergoes a dimer-to-monomer transition at pH 2.0, whereas HdeB remains dimeric at pH 4.0. The monomerization of HdeA exposes its hydrophobic motifs, which facilitates its interaction with the partially folded substrates. How HdeB functions despite maintaining its dimeric conformation has been poorly elucidated in the literature. Herein, we characterized the conformational states and stability of HdeB at its physiologically relevant pH and compared the data with those of HdeA. At pH 4.0, HdeB exhibited distinct spectroscopic signatures and higher stability against heat and guanidine-HCl-induced denaturation than at pH 7.5. We affirm that the pH 4.0 conformer of HdeB was distinct from that at pH 7.5 and that these two conformational states were hierarchically unrelated. Salt-bridge mutations that perturbed HdeB's intersubunit interactions resulted in the loss of its stability and function at pH 4.0. In contrast, mutations affecting intrasubunit interactions enhanced its function, albeit with a reduction in stability. These findings suggest that, unlike HdeA, HdeB acts as a noncanonical chaperone, where pH-dependent stability and conformational rearrangement at pH 4.0 play a core role in its chaperone function rather than its surface hydrophobicity. Such rearrangement establishes a stability-function trade-off that allows HdeB to function while maintaining its stable dimeric state.
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Affiliation(s)
- Charu Thapliyal
- School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
| | - Rajesh Mishra
- School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
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Peng H, Huang Y, Wei G, Pang Y, Yuan H, Zou X, Xie Y, Chen W. Testicular Toxicity in Rats Exposed to AlCl 3: a Proteomics Study. Biol Trace Elem Res 2024; 202:1084-1102. [PMID: 37382810 DOI: 10.1007/s12011-023-03745-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 06/22/2023] [Indexed: 06/30/2023]
Abstract
Aluminum contamination is a growing environmental and public health concern, and aluminum testicular toxicity has been reported in male rats; however, the underlying mechanisms of this toxicity are unclear. The objective of this study was to investigate the effects of exposure to aluminum chloride (AlCl3) on alterations in the levels of sex hormones (testosterone [T], luteinizing hormone [LH], and follicle-stimulating hormone [FSH]) and testicular damage. Additionally, the mechanisms of toxicity in the testes of AlCl3-exposed rats were analyzed by proteomics. Three different concentrations of AlCl3 were administered to rats. The results demonstrated a decrease in T, LH, and FSH levels with increasing concentrations of AlCl3 exposure. HE staining results revealed that the spermatogenic cells in the AlCl3-exposed rats were widened, disorganized, or absent, with increased severe tissue destruction at higher concentrations of AlCl3 exposure. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses revealed that differentially expressed proteins (DEPs) after AlCl3 exposure were primarily associated with various metabolic processes, sperm fibrous sheath, calcium-dependent protein binding, oxidative phosphorylation, and ribosomes. Subsequently, DEPs from each group were subjected to protein-protein interaction (PPI) analysis followed by the screening of interactional key DEPs. Western blot experiments validated the proteomics data, revealing the downregulation of sperm-related DEPs (AKAP4, ODF1, and OAZ3) and upregulation of regulatory ribosome-associated protein (UBA52) and mitochondrial ribosomal protein (MRPL32). These findings provide a basis for studying the mechanism of testicular toxicity due to AlCl3 exposure.
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Affiliation(s)
- Huixin Peng
- The Affiliated Hospital of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China
- Graduate School of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China
| | - Yanxin Huang
- The Affiliated Hospital of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China
- Graduate School of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China
| | - Guangji Wei
- The Affiliated Hospital of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China
- Graduate School of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China
| | - Yanfang Pang
- The Affiliated Hospital of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China
- Graduate School of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China
| | - Huixiong Yuan
- The Affiliated Hospital of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China
- Graduate School of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China
| | - Xiong Zou
- Guangxi Key Laboratory of reproductive health and birth defect prevention, Nanning, 530000, Guangxi, China
| | - Yu'an Xie
- Guangxi Key Laboratory of reproductive health and birth defect prevention, Nanning, 530000, Guangxi, China.
| | - Wencheng Chen
- The Affiliated Hospital of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China.
- Graduate School of You jiang Medical University for Nationalities, Baise, 533000, Guangxi, China.
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Houwman JA, Westphal AH, Visser AJWG, Borst JW, van Mierlo CPM. Concurrent presence of on- and off-pathway folding intermediates of apoflavodoxin at physiological ionic strength. Phys Chem Chem Phys 2018; 20:7059-7072. [PMID: 29473921 DOI: 10.1039/c7cp07922b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Flavodoxins have a protein topology that can be traced back to the universal ancestor of the three kingdoms of life. Proteins with this type of architecture tend to temporarily misfold during unassisted folding to their native state and form intermediates. Several of these intermediate species are molten globules (MGs), which are characterized by a substantial amount of secondary structure, yet without the tertiary side-chain packing of natively folded proteins. An off-pathway MG is formed at physiological ionic strength in the case of the F44Y variant of Azotobacter vinelandii apoflavodoxin (i.e., flavodoxin without flavin mononucleotide (FMN)). Here, we show that at this condition actually two folding species of this apoprotein co-exist at equilibrium. These species were detected by using a combination of FMN fluorescence quenching upon cofactor binding to the apoprotein and of polarized time-resolved tryptophan fluorescence spectroscopy. Besides the off-pathway MG, we observe the simultaneous presence of an on-pathway folding intermediate, which is native-like. Presence of concurrent intermediates at physiological ionic strength enables future exploration of how aspects of the cellular environment, like for example involvement of chaperones, affect these species.
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Affiliation(s)
- Joseline A Houwman
- Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
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de Oliveira GA, Silva JL. The push-and-pull hypothesis in protein unfolding, misfolding and aggregation. Biophys Chem 2017; 231:20-26. [DOI: 10.1016/j.bpc.2017.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 03/25/2017] [Accepted: 03/27/2017] [Indexed: 01/17/2023]
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Pathak BK, Banerjee S, Mondal S, Chakraborty B, Sengupta J, Barat C. Unfolded protein exhibits antiassociation activity toward the 50S subunit facilitating 70S ribosome dissociation. FEBS J 2017; 284:3915-3930. [DOI: 10.1111/febs.14282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 09/05/2017] [Accepted: 09/26/2017] [Indexed: 01/24/2023]
Affiliation(s)
- Bani K. Pathak
- Department of Biotechnology St Xavier's College KolkataIndia
- Structural Biology and Bio‐Informatics Division Indian Institute of Chemical Biology (Council of Scientific and Industrial Research) Kolkata India
| | | | - Surojit Mondal
- Department of Biotechnology St Xavier's College KolkataIndia
| | - Biprashekhar Chakraborty
- Structural Biology and Bio‐Informatics Division Indian Institute of Chemical Biology (Council of Scientific and Industrial Research) Kolkata India
| | - Jayati Sengupta
- Structural Biology and Bio‐Informatics Division Indian Institute of Chemical Biology (Council of Scientific and Industrial Research) Kolkata India
| | - Chandana Barat
- Department of Biotechnology St Xavier's College KolkataIndia
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