肠道病原微生物 z-bo 2020-09-24 469

　　Recently, Chen Peng's research group from the School of Chemistry at Peking University published a paper entitled "Comparative proteomics reveal distinct chaperone-client interactions in supporting bacterial acid resistance" (doi: 10.1073/pnas.1606360113) in the Proceedings of the National Academy of Sciences (PNAS) , Using the newly developed "comparative proteomics" technology, revealed a new mechanism of E. coli resistance to acid stimulation.

　　The unique anti-acid mechanism of intestinal pathogenic microorganisms allows them to smoothly pass through the strong acid environment of human gastric juice, and then cause infection in the intestinal tract, which may even lead to death. HdeA and HdeB are currently the only set of acid-fast chaperone systems found in the membrane stroma of these pathogenic microorganisms, and they are highly conserved among many intestinal bacteria. Therefore, studying their mechanisms of resisting the strong acid environment will help us better understand the relationship between these pathogens and their hosts. In addition, HdeA and HdeB are typical conditional disordered molecular chaperone proteins that use disordered structures to interact with a variety of different substrate proteins to perform their functions. Research on them can also help us better understand the disordered structure of proteins. The relationship between functions. Chen Peng's research group at Peking University College of Chemistry has been committed to the capture and research of acid-fast chaperone protein substrates. In their previous work, they cooperated with the Chang Yii Group of the School of Life Sciences of Peking University to develop a genetically encoded protein photocrosslinking probe DiZPK. Using E. coli as a model, they successfully captured and identified the substrate protein of HdeA. , Revealing the unique molecular chaperone cooperation mechanism of bacteria in resisting acid stress (Nat Chem Biol 7(10):671–677.).

　　In the newly published work, in order to further reveal how these two seemingly redundant molecular chaperones HdeA and HdeB cooperate with each other and protect a large number of different substrate proteins while avoiding non-specific binding, Chen Peng's project The group combined a new generation of cleavable light-crosslinking probe DiZSeK with fluorescent differential two-dimensional gel electrophoresis (2D-DIGE), and developed a "comparative proteomics" strategy called CAPP-DIGE. Direct comparison with HdeB's entire substrate protein group and mass spectrometry identification.

　　"The results show that HdeA and HdeB show significant differences in substrate proteins under living cell conditions. Further research found that this difference comes from the different responses of the two to acid stimulation, making HdeA and HdeB respectively protect the substrate protein group with different tolerance to acid stimulation. During the acid recovery process, they further found that the substrate is also regulated by pH when released by the molecular chaperone, and this pH-regulated substrate release process ensures the effective refolding of the substrate during the acid recovery process.

　　Based on the above research results, they proposed that the pH control mechanism for the substrate specificity of molecular chaperones in the process of bacterial resistance to acid stress, that is, pH systematically regulates the folding state and function of HdeA, HdeB and substrate proteins to allow molecular chaperones The protein is gradually activated under different conditions and coordinated to protect different client proteins, while ensuring that the substrate protein is effectively refolded after being released. This model provides an efficient, economical, flexible and coordinated protein quality control strategy for bacteria to resist acid stimulation. This regulatory mechanism is likely to be applicable to other disordered molecular chaperone systems, and this newly developed CAPP-DIGE technology is useful for identifying and comparing protein-protein interactions and changes under dynamic conditions using proteomics. Application prospects.