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Mahoney BJ, Goring AK, Wang Y, Dasika P, Zhou A, Grossbard E, Cascio D, Loo JA, Clubb RT. Development and atomic structure of a new fluorescence-based sensor to probe heme transfer in bacterial pathogens. J Inorg Biochem 2023; 249:112368. [PMID: 37729854 DOI: 10.1016/j.jinorgbio.2023.112368] [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: 04/30/2023] [Revised: 08/11/2023] [Accepted: 09/07/2023] [Indexed: 09/22/2023]
Abstract
Heme is the most abundant source of iron in the human body and is actively scavenged by bacterial pathogens during infections. Corynebacterium diphtheriae and other species of actinobacteria scavenge heme using cell wall associated and secreted proteins that contain Conserved Region (CR) domains. Here we report the development of a fluorescent sensor to measure heme transfer from the C-terminal CR domain within the HtaA protein (CR2) to other hemoproteins within the heme-uptake system. The sensor contains the CR2 domain inserted into the β2 to β3 turn of the Enhanced Green Fluorescent Protein (EGFP). A 2.45 Å crystal structure reveals the basis of heme binding to the CR2 domain via iron-tyrosyl coordination and shares conserved structural features with CR domains present in Corynebacterium glutamicum. The structure and small angle X-ray scattering experiments are consistent with the sensor adopting a V-shaped structure that exhibits only small fluctuations in inter-domain positioning. We demonstrate heme transfer from the sensor to the CR domains located within the HtaA or HtaB proteins in the heme-uptake system as measured by a ∼ 60% increase in sensor fluorescence and native mass spectrometry.
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Affiliation(s)
- Brendan J Mahoney
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA; UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Andrew K Goring
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Yueying Wang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Poojita Dasika
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Anqi Zhou
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Emmitt Grossbard
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Duilio Cascio
- UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Joseph A Loo
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA; UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Robert T Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA; UCLA-DOE Institute of Genomics and Proteomics, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, 611 Charles E. Young Drive East, Los Angeles, CA 90095, USA.
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Celis AI, Gauss GH, Streit BR, Shisler K, Moraski GC, Rodgers KR, Lukat-Rodgers GS, Peters JW, DuBois JL. Structure-Based Mechanism for Oxidative Decarboxylation Reactions Mediated by Amino Acids and Heme Propionates in Coproheme Decarboxylase (HemQ). J Am Chem Soc 2017; 139:1900-1911. [PMID: 27936663 PMCID: PMC5348300 DOI: 10.1021/jacs.6b11324] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Coproheme decarboxylase catalyzes two sequential oxidative decarboxylations with H2O2 as the oxidant, coproheme III as substrate and cofactor, and heme b as the product. Each reaction breaks a C-C bond and results in net loss of hydride, via steps that are not clear. Solution and solid-state structural characterization of the protein in complex with a substrate analog revealed a highly unconventional H2O2-activating distal environment with the reactive propionic acids (2 and 4) on the opposite side of the porphyrin plane. This suggested that, in contrast to direct C-H bond cleavage catalyzed by a high-valent iron intermediate, the coproheme oxidations must occur through mediating amino acid residues. A tyrosine that hydrogen bonds to propionate 2 in a position analogous to the substrate in ascorbate peroxidase is essential for both decarboxylations, while a lysine that salt bridges to propionate 4 is required solely for the second. A mechanism is proposed in which propionate 2 relays an oxidizing equivalent from a coproheme compound I intermediate to the reactive deprotonated tyrosine, forming Tyr•. This residue then abstracts a net hydrogen atom (H•) from propionate 2, followed by migration of the unpaired propionyl electron to the coproheme iron to yield the ferric harderoheme and CO2 products. A similar pathway is proposed for decarboxylation of propionate 4, but with a lysine residue as an essential proton shuttle. The proposed reaction suggests an extended relay of heme-mediated e-/H+ transfers and a novel route for the conversion of carboxylic acids to alkenes.
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Affiliation(s)
- Arianna I. Celis
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717-3400
| | - George H. Gauss
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717-3400
| | - Bennett R. Streit
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717-3400
| | - Krista Shisler
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717-3400
| | - Garrett C. Moraski
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717-3400
| | - Kenton R. Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108-6050
| | - Gudrun S. Lukat-Rodgers
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108-6050
| | - John W. Peters
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717-3400
| | - Jennifer L. DuBois
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717-3400
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