Role And Mechanism Of Protein Succinylation On Phototaxis Of Mythimna Separata

Phototactic behavior is one of the important biological characteristics of nocturnal insects.The light-trapping technology based on the phototactic behavior of insects has become an important means of pest forecasting and green control because of its green and pollution-free advantages.However,the phototaxis mechanism of insects is still unclear,which hinders the development of light trapping technology.Previous studies found that the metabolism of reactive oxygen species(ROS)changed significantly after insects responded to light stimulation,suggesting that ROS were involved in the regulation of insect phototaxis.Succinylation is a regulator of ROS metabolism,but its role and mechanism in insect phototaxis remain unclear.In this study,the phototactic insect Mythimna separata was used to study the role and mechanism of protein succinylation modification on the phototaxis of M.separata.The main results are as follows:1.Effects of protein succinylation on phototaxis of M.separataRegulators related to modification of protein succinylation significantly responded to light.The related results are as follows: The levels of total protein succinylation in female and male adults were obviously decreased;light treatment for 5 min,10 min,and 60 min significantly decreased the succinyl-Co A level in females(P < 0.05),and light treatment for 30-120 min significantly increased the level of succinyl-Co A in males(P < 0.01);light treatment significantly decreased the activities of α-ketoglutarate dehydrogenase and succinate dehydrogenase in females and males,while the production rate of succinyl-Co A was significantly increased(P < 0.05);light treatment for 120 min significantly increased the gene expression of desuccinylase SIRT5 in females(P < 0.01).These results indicated that light could induce a decrease in the level of protein succinylation and promote the production of succinyl-Co A and the gene expression of desuccinylase,which indicates the involvement of protein succinylation in the response of M.separata to light stimulation.Injection of desuccinylase inhibitor balsalazide affected the phototaxis of M.separata.The results are as follows: treatment of 20 mg/m L balsalazide significantly reduced the phototaxis score of females(P < 0.01),5 mg/m L、10 mg/m L and 20 mg/m L balsalazide significantly reduced the phototaxis score of males(P < 0.05).These results indicate that protein desuccinylation is closely related to phototaxis in M.separata.2.Regulation of ROS metabolism through protein succinylation in phototaxis of M.separataThe phototaxis of M.separata is regulated by ROS metabolism.In this study,the effects of light on the level of oxidative damage and the activity of ROS metabolizing enzymes in M.separata were examined.The results showed that the levels of malondialdehyde(MDA)and the activity of NADPH oxidase(NOX)in both males and females were significantly increased after light exposure(P < 0.01).The activities of dismutase,glutathione S-transferase,catalase,and glutathione peroxidase fluctuated significantly(P < 0.05),indicating that the metabolism of ROS could respond to light treatment in M.separata.This study also found that the injection of 0.5%-2% hydrogen peroxide significantly decreased the phototaxis score of females and males(P < 0.01),injection of 30 mg/m L,50 mg/m L,and 70 mg/m L glutathione significantly decreased the phototaxis scores of male and female worms(P < 0.01),indicating that ROS are involved in regulating the phototaxis behavior of M.separata.Inhibition of desuccinylase leads to reduction in ROS metabolism rate during the light response in M.separata.Injections of 5 mg/m L,10 mg/m L,and 20 mg/m L of desuccinylase inhibitors significantly increased the level of MDA in M.separata under light treatment(P< 0.05);injections of 5 mg/m L and 10 mg/m L desuccinylase inhibitor significantly reduced NOX activity in females(P < 0.05);injection of 5 mg/m L desuccinylase inhibitor significantly reduced superoxide dismutase activity in females(P < 0.05);injection of 5mg/m L,10 mg/m L and 20 mg/m L desuccinylase inhibitor significantly reduced the glutathione S-transferase enzyme activities of females and males(P < 0.05).The above results suggest the important role of protein desuccinylation in affecting the metabolism of ROS in M.separata in response to light stimulation.3.Analysis of the response of protein succinylation to phototaxis in M.separata based on proteomic technologyProteomic technique was used for identification,quantification and bioinformatics analysis of proteins modified by succinylation during phototaxis in M.separata.A total of466 succinylated proteins and 748 succinylation sites were identified,among which 7 sites on 3 proteins were hypersuccinylated and 130 sites on 100 proteins were desuccinylated.Subcellular localization analysis revealed that these differential proteins were mainly located in the cytoplasm and mitochondria,which are important regions of cell metabolism,suggesting that protein succinylation is related to the metabolic process in M.separata during phototaxis.GO,KEGG,and domain enrichment analysis of succinylated proteins showed that the differential proteins were highly enriched in the redox reaction,cytoskeleton,calcium ion,and cell metabolism,suggesting that succinylation is closely related to ROS metabolism,neuromuscular function,and energy metabolism.Further analysis showed that the succinylated proteins associated with ROS metabolism were mainly enriched in the glutathione antioxidant system and thioredoxin antioxidant system,and were involved in NADPH metabolism.Succinylated proteins in the neuromuscular system are closely related to synaptic vesicles,glutamate metabolism,chloride channels,calcium signaling,and muscle contraction.More than 25 succinylated proteins are involved in a wide range of metabolic processes in M.separata,including the tricarboxylic acid cycle,glycolysis,fatty acid metabolism,oxidative phosphorylation,and amino acid biosynthesis.Based on the above results,we believe that succinylation can affect the phototaxis of M.separata by intervening and coordinating ROS metabolism,energy metabolism,and neuromuscular system.In summary,protein succinylation is involved in regulating the response to light stimulation and the phototactic behavior of M.separata.ROS can regulate the phototaxis of M.separata,and succinylation affects the metabolism of ROS in the process of M.separata responding to photostimulation.Succinylation can affect the phototaxis of M.separata by intervening and coordinating ROS metabolism,energy metabolism,and neuromuscular system.This study found significant changes in ROS metabolism and protein post-translational modification in the phototaxis of M.separata,providing new clues for revealing the molecular mechanism of phototaxis in insects.We studied the succinylation proteome of phototactic behavior in insects for the first time and proposed the potential mechanism of post-translational modification regulating insect phototactic behavior.This study provides new clues for revealing the molecular mechanism of insect phototaxis.