Connection between protein- tyrosine kinase inhibition and coping with oxidative stress in Bacillus subtilis

• 成果类型: Article
• 署名作者: Shi, Lei; Derouiche, Abderahmane; Pandit, Santosh; Alazmi, Meshari; Ventroux, Magali; Kohler, Julie Bonne; Noirot-Gros, Marie-Francoise; Gao, Xin; Mijakovic, Ivan
• 署名单位: Chalmers University of Technology; King Abdullah University of Science & Technology; University Ha'il; King Abdullah University of Science & Technology; Universite Paris Saclay; INRAE; AgroParisTech; Technical University of Denmark
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10675
• DOI: 10.1073/pnas.2321890121
• 发表日期: 2024-06-18
• 关键词: peptide deformylase; physiological consequences; phosphorylation; biosynthesis; mechanisms; modulator; iron

摘要

In bacteria, attenuation of protein - tyrosine phosphorylation occurs during oxidative stress. The main described mechanism behind this effect is the H 2 O 2 - triggered conversion of bacterial phosphotyrosines to protein - bound 3,4 - dihydroxyphenylalanine. This disrupts the bacterial tyrosine phosphorylation - based signaling network, which alters the bacterial polysaccharide biosynthesis. Herein, we report an alternative mechanism, in which oxidative stress leads to a direct inhibition of bacterial protein - tyrosine kinases (BY - kinases). We show that DefA, a minor peptide deformylase, inhibits the activity of BY - kinase PtkA when Bacillus subtilis is exposed to oxidative stress. High levels of PtkA activity are known to destabilize B. subtilis pellicle formation, which leads to higher sensitivity to oxidative stress. Interaction with DefA inhibits both PtkA autophosphorylation and phosphorylation of its substrate Ugd, which is involved in exopolysaccharide formation. Inactivation of defA drastically reduces the capacity of B. subtilis to cope with oxidative stress, but it does not affect the major oxidative stress regulons PerR, OhrR, and Spx, indicating that PtkA inhibition is the main pathway for DefA involvement in this stress response. Structural analysis identified DefA residues Asn95, Tyr150, and Glu152 as essential for interaction with PtkA. Inhibition of PtkA depends also on the presence of a C - terminal alpha- helix of DefA, which resembles PtkA - interacting motifs from known PtkA activators, TkmA, SalA, and MinD. Loss of either the key interacting residues or the inhibitory helix of DefA abolishes inhibition of PtkA in vitro and impairs postoxidative stress recovery in vivo, confirming the involvement of these structural features in the proposed mechanism. Significance Protein- tyrosine phosphorylation is a widespread posttranslational modification. It is involved in the regulation of important cellular processes including cell growth, differentiation, death, pathogenicity, and response to oxidative stress. Eukaryotic organisms usually encounter a burst of tyrosine phosphorylation in response to oxidative stress due to the inactivation of tyrosine phosphatases by reactive oxygen species (ROS). In bacteria, tyrosine phosphorylation levels drop during oxidative stress due to the conversion of phosphotyrosines to 3,4- dihydroxyphenylalanine, triggered by ROS. We report another mechanism of attenuating bacterial tyrosine phosphorylation during oxidative stress. A minor peptide deformylase DefA changes its structure during oxidative stress, interacts with a bacterial protein- tyrosine kinase PtkA, inhibits it, which leads to exopolysaccharide remodeling and helps bacteria cope with oxidative stress.