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Jiang T, Wan G, Zhang H, Gyawali YP, Underbakke ES, Feng C. Mapping the Intersubunit Interdomain FMN-Heme Interactions in Neuronal Nitric Oxide Synthase by Targeted Quantitative Cross-Linking Mass Spectrometry. Biochemistry 2024; 63:1395-1411. [PMID: 38747545 DOI: 10.1021/acs.biochem.4c00157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Nitric oxide synthase (NOS) in mammals is a family of multidomain proteins in which interdomain electron transfer (IET) is controlled by domain-domain interactions. Calmodulin (CaM) binds to the canonical CaM-binding site in the linker region between the FMN and heme domains of NOS and allows tethered FMN domain motions, enabling an intersubunit FMN-heme IET in the output state for NO production. Our previous cross-linking mass spectrometric (XL MS) results demonstrated site-specific protein dynamics in the CaM-responsive regions of rat neuronal NOS (nNOS) reductase construct, a monomeric protein [Jiang et al., Biochemistry, 2023, 62, 2232-2237]. In this work, we have extended our combined approach of XL MS structural mapping and AlphaFold structural prediction to examine the homodimeric nNOS oxygenase/FMN (oxyFMN) construct, an established model of the NOS output state. We employed parallel reaction monitoring (PRM) based quantitative XL MS (qXL MS) to assess the CaM-induced changes in interdomain dynamics and interactions. Intersubunit cross-links were identified by mapping the cross-links onto top AlphaFold structural models, which was complemented by comparing their relative abundances in the cross-linked dimeric and monomeric bands. Furthermore, contrasting the CaM-free and CaM-bound nNOS samples shows that CaM enables the formation of the intersubunit FMN-heme docking complex and that CaM binding induces extensive, allosteric conformational changes across the NOS regions. Moreover, the observed cross-links sites specifically respond to changes in ionic strength. This indicates that interdomain salt bridges are responsible for stabilizing and orienting the output state for efficient FMN-heme IET. Taken together, our targeted qXL MS results have revealed that CaM and ionic strength modulate specific dynamic changes in the CaM/FMN/heme complexes, particularly in the context of intersubunit interdomain FMN-heme interactions.
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Affiliation(s)
- Ting Jiang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Guanghua Wan
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Haikun Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Yadav Prasad Gyawali
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Eric S Underbakke
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Changjian Feng
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
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Kim H, Moore CM, Mestre-Fos S, Hanna DA, Williams LD, Reddi AR, Torres MP. Depletion assisted hemin affinity (DAsHA) proteomics reveals an expanded landscape of heme-binding proteins in the human proteome. Metallomics 2023; 15:6994529. [PMID: 36669767 PMCID: PMC10022665 DOI: 10.1093/mtomcs/mfad004] [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: 08/26/2022] [Accepted: 01/19/2023] [Indexed: 01/22/2023]
Abstract
Heme b (iron protoporphyrin IX) plays important roles in biology as a metallocofactor and signaling molecule. However, the targets of heme signaling and the network of proteins that mediate the exchange of heme from sites of synthesis or uptake to heme dependent or regulated proteins are poorly understood. Herein, we describe a quantitative mass spectrometry (MS)-based chemoproteomics strategy to identify exchange labile hemoproteins in human embryonic kidney HEK293 cells that may be relevant to heme signaling and trafficking. The strategy involves depleting endogenous heme with the heme biosynthetic inhibitor succinylacetone (SA), leaving putative heme-binding proteins in their apo-state, followed by the capture of those proteins using hemin-agarose resin, and finally elution and identification by MS. By identifying only those proteins that interact with high specificity to hemin-agarose relative to control beaded agarose in an SA-dependent manner, we have expanded the number of proteins and ontologies that may be involved in binding and buffering labile heme or are targets of heme signaling. Notably, these include proteins involved in chromatin remodeling, DNA damage response, RNA splicing, cytoskeletal organization, and vesicular trafficking, many of which have been associated with heme through complementary studies published recently. Taken together, these results provide support for the emerging role of heme in an expanded set of cellular processes from genome integrity to protein trafficking and beyond.
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Affiliation(s)
- Hyojung Kim
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Courtney M Moore
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Santi Mestre-Fos
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - David A Hanna
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Loren Dean Williams
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Amit R Reddi
- Correspondence: Amit R. Reddi, School of Chemistry and Biochemistry, Georgia Institute of Technology, 950 Atlantic Dr. Atlanta, GA 30033. E-mail:
| | - Matthew P Torres
- Correspondence: Matthew P. Torres, School of Biological Sciences, Georgia Institute of Technology, 950 Atlantic Dr. Atlanta, GA 30033. E-mail:
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Zheng H, Li J, Feng C. An isoform-specific pivot modulates the electron transfer between the flavin mononucleotide and heme centers in inducible nitric oxide synthase. J Biol Inorg Chem 2020; 25:1097-1105. [PMID: 33057871 PMCID: PMC7669679 DOI: 10.1007/s00775-020-01824-w] [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: 06/14/2020] [Accepted: 09/24/2020] [Indexed: 11/25/2022]
Abstract
Intraprotein interdomain electron transfer (IET) between the flavin mononucleotide (FMN) and heme centers is an obligatory step in nitric oxide synthase (NOS) enzymes. An isoform-specific pivotal region near Leu406 in the heme domain of human inducible NOS (iNOS) was proposed to mediate the FMN-heme domain-domain alignment (J Inorg Biochem 153:186-196, 2015). The FMN-heme IET rate is a measure of the interdomain FMN/heme complex formation. In this work, the FMN-heme IET kinetics in the wild type (wt) human iNOS oxygenase/FMN (oxyFMN) construct were directly measured by laser flash photolysis with added synthetic peptide related to the pivotal region, in comparison with the wt construct alone. The IET rates were decreased by the iNOS HKL peptide in a dose-saturable fashion, and the inhibitory effect was abolished by a single L406 → E mutation in the peptide. A similar trend in change of the NO synthesis activity of wt iNOS holoenzyme by the peptides was observed. These data, along with the kinetics and modeling results for the L406T and L406F mutant oxyFMN proteins, indicated that the Leu406 residue modulates the FMN-heme IET through hydrophobic interactions. Moreover, the IET rates were analyzed for the wt iNOS oxyFMN protein in the presence of nNOS or eNOS-derived peptide related to the equivalent pivotal heme domain site. These results together indicate that the isoform-specific pivotal region at the heme domain specifically interacts with the conserved FMN domain surface, to facilitate proper interdomain docking for the FMN-heme IET in NOS.
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Affiliation(s)
- Huayu Zheng
- College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Jinghui Li
- College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Changjian Feng
- College of Pharmacy, University of New Mexico, Albuquerque, NM, 87131, USA.
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
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Zheng H, Weaver JM, Feng C. Heat shock protein 90α increases superoxide generation from neuronal nitric oxide synthases. J Inorg Biochem 2020; 214:111298. [PMID: 33181440 DOI: 10.1016/j.jinorgbio.2020.111298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 10/18/2020] [Accepted: 10/24/2020] [Indexed: 11/15/2022]
Abstract
Neuronal nitric oxide synthase (nNOS) generates superoxide, particularly at sub-optimal l-arginine (l-Arg) substrate concentrations. Heat shock protein 90 (Hsp90) was reported to inhibit superoxide generation from nNOS protein. However, commercially available Hsp90 product from bovine brain tissues with unspecified Hsp90α and Hsp90β contents and an undefined Hsp90 protein oligomeric state was utilized. These two Hsp90s can have opposite effect on superoxide production by NOS. Importantly, emerging evidence indicates that nNOS splice variants are involved in different biological functions by functioning distinctly in redox signaling. In the present work, purified recombinant human Hsp90α, in its native dimeric state, was used in electron paramagnetic resonance (EPR) spin trapping experiments to study the effects of Hsp90α on superoxide generation from nNOS splice variants nNOSμ and nNOSα. Human Hsp90α was found to significantly increase superoxide generation from nNOSμ and nNOSα proteins under l-Arg-depleted conditions and Hsp90α influenced superoxide production by nNOSμ and nNOSα at varying degrees. Imidazole suppressed the spin adduct signal, indicating that superoxide was produced at the heme site of nNOS in the presence of Hsp90α, whereas l-Arg repletion diminished superoxide production by the nNOS-Hsp90α. Moreover, NADPH consumption rate values exhibited a similar trend/difference as a function of Hsp90α and l-Arg. Together, these EPR spin trapping and NADPH oxidation kinetics results demonstrated noticeable Hsp90α-induced increases in superoxide production by nNOS and a distinguishable effect of Hsp90α on nNOSμ and nNOSα proteins.
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Affiliation(s)
- Huayu Zheng
- College of Pharmacy, University of New Mexico, Albuquerque, NM 87131, USA; Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - John M Weaver
- College of Pharmacy, University of New Mexico, Albuquerque, NM 87131, USA
| | - Changjian Feng
- College of Pharmacy, University of New Mexico, Albuquerque, NM 87131, USA; Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA.
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