D-alanine （D-Ala） is an essential amino acid that has a key role in bacterial unique enzyme that interconverts L-alanine and D-alanine in most bacteria, antimicrobial drug development. Streptococcus mutans is a majo...D-alanine （D-Ala） is an essential amino acid that has a key role in bacterial unique enzyme that interconverts L-alanine and D-alanine in most bacteria, antimicrobial drug development. Streptococcus mutans is a major causative cell wall synthesis. Alanine racemase （Air） is a making this enzyme a potential target for factor of dental caries. The factors involved in the survival, virulence and interspecies interactions of S. mutans could be exploited as potential targets for caries control. The current study aimed to investigate the physiological role of Air in S. mutans. We constructed air mutant strain of S. mutans and evaluated its phenotypic traits and interspecies competitiveness compared with the wild-type strain. We found that air deletion was lethal to S. mutans. A minimal supplement of D-Ala （150 pg.mL- 1） was required for the optimal growth of the air mutant. The depletion of D-alanine in the growth medium resulted in cell wall perforation and cell lysis in the air mutant strain. We also determined the compromised competitiveness of the air mutant strain relative to the wild-type S. mutans against other oral streptococci （S. sanguinis or S. gordonil~, demonstrated using either conditioned medium assays or dual-species fluorescent in situ hybridization analysis. Given the importance and necessity of air to the growth and competitiveness of S. mutans, Air may represent a promising target to modulate the cariogenicity of oral biofilms and to benefit the management of dental caries.展开更多
Aims More and more advances show that hydrogen sulfide （H2S） sulfhydrates functional proteins and regulates their actions. However, much less is known about the endogenous sulfhydration of key proteins under physiol...Aims More and more advances show that hydrogen sulfide （H2S） sulfhydrates functional proteins and regulates their actions. However, much less is known about the endogenous sulfhydration of key proteins under physiological conditions. Methods Biotin-switch assay, electrophysiological recording, RNA interference, full ESI-MS scan et al. Results Herein, we found that the protein sulfhydration was dynamically regulated by neuro- nal activity. H2S sulfhydrated and activated serine racemase （SR） in the hippocampus, resuhantly increased D- serine level. Notably, sulfhydration of SR was markedly promoted by neuronal stimulation and underlay activity-de- pendent changes of D-serine availability. Both genetic knockdown and pharmacological inhibition of cystathionine β-synthase （CBS）, the key H2S-producing enzyme in brain, attenuated hippoeampal long-term potentiation （LTP） , which can be reversed by exogenous supplement of H2S or D-serine. We also observed that the increase in LTP induced by H2S is dependent on D-serine and polysulfides. In aged rats, sulfhydration of SR was significantly decreased. Furthermore, exogenous supplement of H2S restored the level of sulfhydration and reversed the age-re- lated deficits in hippocampal LTP. Conclusion Our data provide direct evidence for the biological significance of endogenous sulfhydration in physiological conditions and demonstrate a pivotal role of activity-dependent sulfhydra- tion in synaptic plasticity.展开更多
哺乳动物中枢神经系统中 D 构象丝氨酸的区域性高浓度分布与N 甲基 D 天冬氨酸 (NMDA)受体相一致 .它主要由丝氨酸消旋酶将 L 丝氨酸直接消旋而来 ,也可能通过肠道菌群产生后吸收至体内 ,最终被 D 构象氨基酸氧化酶氧化 .这种从胶质细...哺乳动物中枢神经系统中 D 构象丝氨酸的区域性高浓度分布与N 甲基 D 天冬氨酸 (NMDA)受体相一致 .它主要由丝氨酸消旋酶将 L 丝氨酸直接消旋而来 ,也可能通过肠道菌群产生后吸收至体内 ,最终被 D 构象氨基酸氧化酶氧化 .这种从胶质细胞而非神经元来源的“异常”构象氨基酸作为一种新型神经递质 ,不仅更新了传统“神经递质”的定义 。展开更多
基金financially supported through grants from the National Natural Science Foundation of China (81400501 to Ming-Yun Li, 81371135 to Ji-Yao Li and 81430011 to Xue-Dong Zhou)the International Science and Technology Cooperation Programme of China (2014DFE30180 to Xue-Dong Zhou)+1 种基金the Talented Young Investigator Award of Sichuan University (2082604184224 to Xin Xu)the Special Fund of State Key Laboratory of Oral Diseases, Sichuan University (SKLOD201525 to Ming-Yun Li)
文摘D-alanine （D-Ala） is an essential amino acid that has a key role in bacterial unique enzyme that interconverts L-alanine and D-alanine in most bacteria, antimicrobial drug development. Streptococcus mutans is a major causative cell wall synthesis. Alanine racemase （Air） is a making this enzyme a potential target for factor of dental caries. The factors involved in the survival, virulence and interspecies interactions of S. mutans could be exploited as potential targets for caries control. The current study aimed to investigate the physiological role of Air in S. mutans. We constructed air mutant strain of S. mutans and evaluated its phenotypic traits and interspecies competitiveness compared with the wild-type strain. We found that air deletion was lethal to S. mutans. A minimal supplement of D-Ala （150 pg.mL- 1） was required for the optimal growth of the air mutant. The depletion of D-alanine in the growth medium resulted in cell wall perforation and cell lysis in the air mutant strain. We also determined the compromised competitiveness of the air mutant strain relative to the wild-type S. mutans against other oral streptococci （S. sanguinis or S. gordonil~, demonstrated using either conditioned medium assays or dual-species fluorescent in situ hybridization analysis. Given the importance and necessity of air to the growth and competitiveness of S. mutans, Air may represent a promising target to modulate the cariogenicity of oral biofilms and to benefit the management of dental caries.
文摘Aims More and more advances show that hydrogen sulfide （H2S） sulfhydrates functional proteins and regulates their actions. However, much less is known about the endogenous sulfhydration of key proteins under physiological conditions. Methods Biotin-switch assay, electrophysiological recording, RNA interference, full ESI-MS scan et al. Results Herein, we found that the protein sulfhydration was dynamically regulated by neuro- nal activity. H2S sulfhydrated and activated serine racemase （SR） in the hippocampus, resuhantly increased D- serine level. Notably, sulfhydration of SR was markedly promoted by neuronal stimulation and underlay activity-de- pendent changes of D-serine availability. Both genetic knockdown and pharmacological inhibition of cystathionine β-synthase （CBS）, the key H2S-producing enzyme in brain, attenuated hippoeampal long-term potentiation （LTP） , which can be reversed by exogenous supplement of H2S or D-serine. We also observed that the increase in LTP induced by H2S is dependent on D-serine and polysulfides. In aged rats, sulfhydration of SR was significantly decreased. Furthermore, exogenous supplement of H2S restored the level of sulfhydration and reversed the age-re- lated deficits in hippocampal LTP. Conclusion Our data provide direct evidence for the biological significance of endogenous sulfhydration in physiological conditions and demonstrate a pivotal role of activity-dependent sulfhydra- tion in synaptic plasticity.
文摘哺乳动物中枢神经系统中 D 构象丝氨酸的区域性高浓度分布与N 甲基 D 天冬氨酸 (NMDA)受体相一致 .它主要由丝氨酸消旋酶将 L 丝氨酸直接消旋而来 ,也可能通过肠道菌群产生后吸收至体内 ,最终被 D 构象氨基酸氧化酶氧化 .这种从胶质细胞而非神经元来源的“异常”构象氨基酸作为一种新型神经递质 ,不仅更新了传统“神经递质”的定义 。
