Dataset Information

Mapping Interactions of Calmodulin and nNOS by CXL-MS

ABSTRACT: Neuronal nitric oxide synthase (nNOS) is a self-sufficient homodimeric cytochrome P450-like enzyme that catalyzes the conversion of L-arginine to nitric oxide in the presence of NADPH and molecular oxygen. The binding of calmodulin (CaM) to a linker region between the FAD/FMN containing reductase domain and the heme containing oxygenase domain, greatly enhances electron transfer reactions allowing reduction of the heme and NO synthesis. Due to the dynamic nature of the nNOS reductase domain and the overall low resolution of full-length nNOS structures, the exact nature of the CaM-bound active complex during heme reduction is still unresolved. Interestingly, hydrogen-deuterium exchange and mass spectrometry (HDX-MS) studies on iNOS, but not nNOS, directly revealed interactions of the FMN-domain and CaM with the oxygenase domain. To further address this unexpected finding with nNOS, we utilized covalent crosslinking and mass spectrometry (CXL-MS) to examine interactions of CaM with full- length nNOS. Specifically, MS-cleavable bifunctional crosslinker disuccinimidyl dibutyric urea was used to identify thirteen unique crosslinks between CaM and nNOS as well as 61 crosslinks within the nNOS. Detailed analysis of the crosslinks provide evidence for CaM interaction with the oxygenase and reductase domain residues as well as interactions of the FMN-domain with the oxygenase dimer. Crosslink-guided docking studies reveal a conformation of nNOS that brings the FMN within 15 Å to the heme and provides further support for a more compact conformation of CaM-bound nNOS than previously observed in EM-derived structures. These studies also point to the utility of CXL-MS to capture transient dynamic conformations that may not be captured by HDX-MS experiments.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Rattus Norvegicus (rat)

SUBMITTER: Dana Felker

LAB HEAD: Yoichi Osawa

PROVIDER: PXD044750 | Pride | 2024-01-26

REPOSITORIES: Pride

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Publications

Mapping interactions of calmodulin and neuronal NO synthase by crosslinking and mass spectrometry.

Felker Dana D Lee Kanghyun K Pospiech Thomas H TH Morishima Yoshihiro Y Zhang Haoming H Lau Miranda M Southworth Daniel R DR Osawa Yoichi Y

The Journal of biological chemistry 20231116 1

Neuronal nitric oxide synthase (nNOS) is a homodimeric cytochrome P450-like enzyme that catalyzes the conversion of L-arginine to nitric oxide in the presence of NADPH and molecular oxygen. The binding of calmodulin (CaM) to a linker region between the FAD/FMN-containing reductase domain, and the heme-containing oxygenase domain is needed for electron transfer reactions, reduction of the heme, and NO synthesis. Due to the dynamic nature of the reductase domain and low resolution of available ful ...[more]

PMID: 37979917

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Project description:Nitric oxide (NO) is involved in all major environmental stresses. However, most of these understandings were mainly based on pharmacological study using NO modulator compounds. Recently, our studies together with others provided a new class of plant experimental system with specific in vivo NO release through constitutively overexpressing rat neuronal NO synthase (nNOS) in plants. In this study, we found that the nNOS transgenic Arabidopsis plants displayed lower level of H2O2 content, but higher levels of antioxidant enzyme activities and osmolytes under drought stress conditions. Transcriptomic analysis identified 490 and 20 genes that were differentially expressed in wild type (WT) and nNOS transgenic plants under control and drought stress conditions, respectively. Pathway analysis revealed that many genes involved in photosynthesis, cell, misc, co-factor and vitamin metabolism, major CHO metabolism, OPP and secondary metabolism were largely changed in nNOS vs. WT under control or drought stress conditions. Interestingly, CBF1/2 and 13 zinc finger family proteins, known as important family of transcription regulators in modulating several stress-responsive genes, were differentially expressed by nNOS transgenic effect. Additionally, some genes were commonly regulated by nNOS transgenic and abscisic acid (ABA) effects, indicating new insights to cross-talk between ABA and NO. Taken together, in vivo NO modulated antioxidant enzyme activities, osmolyte level, and the expression of genes involved in several pathways, thereby resulting in enhanced stress tolerance in nNOS transgenic plants. These observations might provide some insights to understand the physiological and molecular mechanisms of NO in response to drought stress in Arabidopsis. Two transgenic Arabidopsis lines (nNOS-2 and nNOS-25) with the nNOS gene under the control of the cauliflower mosaic virus (CaMV) 35S promoter, as well as Col-0 (WT), were used in this research. RNA samples from two nNOS transgenic lines were pooled for cRNA labelling and chip hybridization.

Project description:The response regulator HrrA belonging to the HrrSA two-component system (previously named CgtSR11) is known to be repressed by the global iron-dependent regulator DtxR in Corynebacterium glutamicum. Sequence analysis indicated an involvement of the HrrSA system in heme-dependent gene expression. Growth experiments revealed that the non-pathogenic soil bacterium C. glutamicum is able to use hemin or hemoglobin as sole iron source. In DNA microarray analyses a putative operon encoding the hemin-binding protein HtaA and the putative hemin ABC transporter HmuTUV showed a strong upregulation in heme-grown cells. Deletion of the hmu operon clearly affects heme utilization, but does not completely abolish growth on heme or hemoglobin. As a central part of this study, we investigated the regulon of the response regulator HrrA via comparative transcriptome analysis of a hrrA deletion mutant and C. glutamicum wild type in combination with DNA-protein interaction studies with purified HrrA protein. Our data provide evidence for a heme-dependent transcriptional activation of heme oxygenase (hmuO), an enzyme involved in the utilization of heme as iron source. Besides hmuO, HrrA was shown to activate the expression of heme-containing components of the respiratory chain, namely ctaD and the ctaE-qcrCAB operon encoding subunits I and III of cytochrome aa3 oxidase and three subunits of the cytochrome bc1 complex. Furthermore, HrrA represses almost all genes involved in heme biosynthesis, including glutamyl-tRNA reductase (hemA), uroporphyrinogen decarboxylase (hemE), and ferrochelatase (hemH). Thus, our data clearly emphasize a central role of the HrrSA system in the control of heme homeostasis in C. glutamicum. Three biological replicates of each experiment were performed. Experiment 1: Transcriptome comparison of wild type grown und FeSO4 or heme as iron source; Exp. 2: WT vs. hrrA deletion mutant grown on FeSO4; Exp. 3: WT vs. hrrA mutant grown on heme. For analysis via DNA microarraysose RNA was isolated from exponentially growing cells cultivated in CgXII medium containing glucose as carbon source and either 2.5 uM FeSO4 or 2.5 uM heme as iron source.

Project description:Stone1996 - activation of soluble guanylate cyclase by nitric oxide This features the two step binding of NO to soluble Guanylyl Cyclase as proposed by Stone JR, Marletta MA. Biochemistry (1996) 35(4):1093-9 . There is a fast step binding scheme and a slow step binding scheme. The difference lies in the binding of a NO to a non-heme site on sGC, which may not necessarily be the same site of binding during the initial binding. The rates have been directly used models. This model is described in the article: Spectral and kinetic studies on the activation of soluble guanylate cyclase by nitric oxide. Stone JR, Marletta MA. Biochemistry 1996 Jan; 35(4): 1093-1099 Abstract: The soluble form of guanylate cyclase (sGC) is the only definitive receptor for the signaling agent nitric oxide (.NO). The enzyme is a heterodimer of homologous subunits in which each subunit binds 1 equiv of 5-coordinate high-spin heme. .NO increases the Vmax of sGC up to 400-fold and has previously been shown to bind to the heme to form a 5-coordinate complex. Using stopped-flow spectrophotometry, it is demonstrated that the binding of .NO to the heme of sGC is a complex process. .NO first binds to the heme to form a 6-coordinate nitrosyl complex, which then converts to a 5-coordinate nitrosyl complex through one of two ways. For 28 +/- 4% of the heme, the 6-coordinate nitrosyl complex rapidly (approximately 20 s-1) converts to the 5-coordinate complex. For the remaining 72 +/- 4% of the heme, the conversion of the 6-coordinate nitrosyl complex to a 5-coordinate nitrosyl complex is slow (0.1-1.0 s-1) and is dependent upon the interaction of .NO with an unidentified non-heme site on the protein. The heme (200 nM) was completely converted to the 5-coordinate state with as little as 500 nM .NO, and the equilibrium dissociation constant of .NO for activating the enzyme was determined to be < or = 250 nM. Gel-filtration analysis indicates that the binding of .NO to the heme has no effect on the native molecular mass of the protein. Correlation of electronic absorption spectra with activity measurements indicates that the 5-coordinate nitrosyl form of the enzyme is activated relative to the resting 5-coordinate ferrous form of the enzyme. This model is hosted on BioModels Database and identified by: BIOMD0000000198. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Dataset Information

Mapping Interactions of Calmodulin and nNOS by CXL-MS

Publications

Mapping interactions of calmodulin and neuronal NO synthase by crosslinking and mass spectrometry.

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