Work

Probing Protein Dynamics in Neuronal Nitric Oxide Synthase by Quantitative Cross-Linking Mass Spectrometry

Year: 2023

Type: article

Abstract: Nitric oxide synthase (NOS) is responsible for the biosynthesis of nitric oxide (NO), an important signaling molecule controlling diverse physiological processes such as neurotransmission and vasodilation. Neuronal NOS (nNOS) is a calmodulin (CaM)-controlled enzyme. In the absence of CaM, several intrinsic control elements, along with NADP + binding, suppress electron transfer across the NOS domains. CaM binding relieves the inhibitory factors to promote the electron transport required for NO production. The regulatory dynamics of nNOS control elements are critical to governing NO signaling, yet mechanistic questions remain, because the intrinsic dynamics of NOS thwart traditional structural biology approaches. Here, we have employed cross-linking mass spectrometry (XL MS) to probe regulatory dynamics in nNOS, focusing on the CaM-responsive control elements. Quantitative XL MS revealed conformational changes differentiating the nNOS reductase (nNOSred) alone, nNOSred with NADP +, nNOS-CaM, and nNOS-CaM with NADP + . We observed distinct effects of CaM vs NADP + on cross-linking patterns in nNOSred. CaM induces striking global changes, while the impact of NADP + is primarily localized to the NADPH-binding subdomain. Moreover, CaM increases the abundance of intra-nNOS cross-links that are related to the formation of the inter-CaM-nNOS cross-links. Taken together, these XL MS results demonstrate that CaM and NADP + site-specifically alter the nNOS conformational landscape.

Source: Biochemistry

DOI: 10.1021/acs.biochem.3c00245

Authors: Ting Jiang, Guanghua Wan, Haikun Zhang, Yadav Prasad Gyawali, Eric S. Underbakke, Changjian Feng

Institutions: University of New Mexico, Iowa State University

Language: English

Topic: Mass Spectrometry Techniques and Applications

Subfield: Spectroscopy

Field: Chemistry

Domain: Physical Sciences

Open Access status: green