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Dehinwal R, Gopinath T, Smith RD, Ernst RK, Schifferli DM, Waldor MK, Marassi FM. A pH-sensitive motif in an outer membrane protein activates bacterial membrane vesicle production. Nat Commun 2024; 15:6958. [PMID: 39138228 PMCID: PMC11322160 DOI: 10.1038/s41467-024-51364-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 08/02/2024] [Indexed: 08/15/2024] Open
Abstract
Outer membrane vesicles (OMVs) produced by Gram-negative bacteria have key roles in cell envelope homeostasis, secretion, interbacterial communication, and pathogenesis. The facultative intracellular pathogen Salmonella Typhimurium increases OMV production inside the acidic vacuoles of host cells by changing expression of its outer membrane proteins and modifying the composition of lipid A. However, the molecular mechanisms that translate pH changes into OMV production are not completely understood. Here, we show that the outer membrane protein PagC promotes OMV production through pH-dependent interactions between its extracellular loops and surrounding lipopolysaccharide (LPS). Structural comparisons and mutational studies indicate that a pH-responsive amino acid motif in PagC extracellular loops, containing PagC-specific histidine residues, is crucial for OMV formation. Molecular dynamics simulations suggest that protonation of histidine residues leads to changes in the structure and flexibility of PagC extracellular loops and their interactions with the surrounding LPS, altering membrane curvature. Consistent with that hypothesis, mimicking acidic pH by mutating those histidine residues to lysine increases OMV production. Thus, our findings reveal a mechanism for sensing and responding to environmental pH and for control of membrane dynamics by outer membrane proteins.
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Affiliation(s)
- Ruchika Dehinwal
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, USA
- Department of Microbiology, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA, USA
| | - Tata Gopinath
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Richard D Smith
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD, USA
| | - Dieter M Schifferli
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Matthew K Waldor
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, USA.
- Department of Microbiology, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA, USA.
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Cheng YC, Lee HL, Hwang Y, Kim SW. The effects of standardized ileal digestible His to Lys ratio on growth performance, intestinal health, and mobilization of histidine-containing proteins in pigs at 7 to 11 kg body weight. J Anim Sci 2023; 101:skac396. [PMID: 36440959 PMCID: PMC9838802 DOI: 10.1093/jas/skac396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022] Open
Abstract
The objectives were to evaluate the effects of standardized ileal digestible (SID) His:Lys ratio above the current NRC requirement on growth performance, intestinal health, and mobilization of His-containing proteins, including hemoglobin, carnosine, and trypsinogen, in nursery pigs from 7 to 11 kg body weight (BW). Forty pigs (26 d of age; initial BW of 7.1 ± 0.5 kg) were allotted to 5 dietary treatments based on a randomized complete block design with sex and initial BW as blocks. Dietary treatments were supplemented with varying SID His to Lys ratios of 26%, 32%, 38%, 43%, and 49% and fed to pigs for 14 d (SID Lys = 1.22%). Feed intake and BW were recorded at d 0, 7, and 14 to measure growth performance. Blood samples were collected on d 12. Pigs were euthanized on d 14 to collect pancreas, longissimus dorsi muscles, mid-jejunum, and jejunal mucosa. Data were analyzed using the Proc Mixed of SAS. Growth performance was not affected, whereas varying SID His to Lys ratio affected hemoglobin (P < 0.05, max: 12 g/dL at 36%), immunoglobulin A (IgA, P < 0.05, min: 1.25 μg/mg at 35%) in jejunal mucosa, villus height (P = 0.065, max: 536 μm at 40%) in jejunum, trypsinogen (P = 0.083, max: 242 pg/mg at 41%) in pancreas, and carnosine (P = 0.051, max: 4.7 ng/mg at 38%) in muscles. Varying SID His to Lys ratios linearly increased (P < 0.05, from 1.95 to 2.80 nmol/mg) protein carbonyl in muscles and decreased (P < 0.05, from 29.1% to 26.9%) enterocyte proliferation. In conclusion, SID His to Lys ratio between 35% and 41% in diets fed to nursery pigs at 7 to 11 kg enhanced intestinal health and maximized concentrations of His-containing proteins, indicating that His-containing proteins are effective response criteria when determining His requirement.
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Affiliation(s)
- Yi-Chi Cheng
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA
| | | | | | - Sung Woo Kim
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA
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D'Alessandro A, Nemkov T, Sun K, Liu H, Song A, Monte AA, Subudhi AW, Lovering AT, Dvorkin D, Julian CG, Kevil CG, Kolluru GK, Shiva S, Gladwin MT, Xia Y, Hansen KC, Roach RC. AltitudeOmics: Red Blood Cell Metabolic Adaptation to High Altitude Hypoxia. J Proteome Res 2016; 15:3883-3895. [PMID: 27646145 DOI: 10.1021/acs.jproteome.6b00733] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Red blood cells (RBCs) are key players in systemic oxygen transport. RBCs respond to in vitro hypoxia through the so-called oxygen-dependent metabolic regulation, which involves the competitive binding of deoxyhemoglobin and glycolytic enzymes to the N-terminal cytosolic domain of band 3. This mechanism promotes the accumulation of 2,3-DPG, stabilizing the deoxygenated state of hemoglobin, and cytosol acidification, triggering oxygen off-loading through the Bohr effect. Despite in vitro studies, in vivo adaptations to hypoxia have not yet been completely elucidated. Within the framework of the AltitudeOmics study, erythrocytes were collected from 21 healthy volunteers at sea level, after exposure to high altitude (5260 m) for 1, 7, and 16 days, and following reascent after 7 days at 1525 m. UHPLC-MS metabolomics results were correlated to physiological and athletic performance parameters. Immediate metabolic adaptations were noted as early as a few hours from ascending to >5000 m, and maintained for 16 days at high altitude. Consistent with the mechanisms elucidated in vitro, hypoxia promoted glycolysis and deregulated the pentose phosphate pathway, as well purine catabolism, glutathione homeostasis, arginine/nitric oxide, and sulfur/H2S metabolism. Metabolic adaptations were preserved 1 week after descent, consistently with improved physical performances in comparison to the first ascendance, suggesting a mechanism of metabolic memory.
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Affiliation(s)
- Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver , Anschutz Medical Campus, Aurora, Colorado 80045, United States
| | - Travis Nemkov
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver , Anschutz Medical Campus, Aurora, Colorado 80045, United States
| | - Kaiqi Sun
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston , Houston, Texas, United States
| | - Hong Liu
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston , Houston, Texas, United States
| | - Anren Song
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston , Houston, Texas, United States
| | - Andrew A Monte
- Altitude Research Center, Department of Emergency Medicine, University of Colorado , Anschutz Medical Campus, Aurora, Colorado, United States
| | - Andrew W Subudhi
- Altitude Research Center, Department of Emergency Medicine, University of Colorado , Anschutz Medical Campus, Aurora, Colorado, United States.,Department of Biology, University of Colorado Colorado Springs , Colorado Springs, Colorado, United States
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon , Eugene, Oregon, United States
| | - Daniel Dvorkin
- Altitude Research Center, Department of Emergency Medicine, University of Colorado , Anschutz Medical Campus, Aurora, Colorado, United States
| | - Colleen G Julian
- Altitude Research Center, Department of Emergency Medicine, University of Colorado , Anschutz Medical Campus, Aurora, Colorado, United States
| | - Christopher G Kevil
- Department of Pathology, Centre for Cardiovascular Diseases and Sciences, LSU Health , Shreveport, Louisiana, United States
| | - Gopi K Kolluru
- Department of Pathology, Centre for Cardiovascular Diseases and Sciences, LSU Health , Shreveport, Louisiana, United States
| | - Sruti Shiva
- Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania, United States
| | - Mark T Gladwin
- Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania, United States
| | - Yang Xia
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston , Houston, Texas, United States
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver , Anschutz Medical Campus, Aurora, Colorado 80045, United States
| | - Robert C Roach
- Altitude Research Center, Department of Emergency Medicine, University of Colorado , Anschutz Medical Campus, Aurora, Colorado, United States
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