Molecular machines transduce energy from one form to another through controlled motion in response to stimuli.Despite the ubiquitous use of molecular machines in biology,understanding the detailed mechanisms of such c...Molecular machines transduce energy from one form to another through controlled motion in response to stimuli.Despite the ubiquitous use of molecular machines in biology,understanding the detailed mechanisms of such complex structures remains challenging.Recent progress in studying the modes of operation of synthetic small-molecule machines at the single-molecule level has shed new light on the mechanisms of nano-machinery.In this mini-review,we focus on the study of artificial small-molecule machines using single-molecule techniques,including single-molecule force spectroscopy,single-molecule electrical spectroscopy,and single-molecule optical spectroscopy.We survey the techniques used to monitor single-molecule behavior to date and describe the latest studies on small-molecule machines,highlighting their common features and challenges that need to be overcome to realize the potential of these techniques in unraveling the behavior of small molecule systems.展开更多
The mechanical stability of tRNAs contributes to their biological activities.The mitochondrial tRNAArg from Romanomermis culicivorax is the shortest tRNA ever known.This tRNA lacks D-and T-arms,represents a stem-bulge...The mechanical stability of tRNAs contributes to their biological activities.The mitochondrial tRNAArg from Romanomermis culicivorax is the shortest tRNA ever known.This tRNA lacks D-and T-arms,represents a stem-bulge-stem architecture but still folds into a stable tertiary structure.Although its structure had been reported,studies on its mechanical folding and unfolding kinetic characteristics are lacking.Here,we directly measured the single-molecule mechanical folding and unfolding kinetics of the armless mt tRNAArg by using optical tweezers in different solution conditions.We revealed a two-step reversible unfolding pathway:the first and large transition corresponds to the unfolding of acceptor stem and bulge below 11 pN,and the second and small transition corresponds to the unfolding of anticodon arm at 12 pN-14 pN.Moreover,the free energy landscapes of the unfolding pathways were reconstructed.We also demonstrated that amino acid-chelated Mg^(2+)(aaCM),which mimics the intracellular solution condition,stabilizes the bulge of mitochondrial tRNAArg possibly by reducing the topological constraints or stabilizing the possible local non-canonical base pairings within the bulge region.Our study revealed the solution-dependent mechanical stability of an armless mt tRNA,which may shed light on future mt tRNA studies.展开更多
Membrane proteins are crucial in cell physiological activities and are the targets for most drugs.Thus,investigating the behaviors of membrane proteins not only provide deeper insights into cell function,but also help...Membrane proteins are crucial in cell physiological activities and are the targets for most drugs.Thus,investigating the behaviors of membrane proteins not only provide deeper insights into cell function,but also help disease treatment and drug development.Atomic force microscopy is a unique tool for investigating the structure of membrane proteins.It can both image the morphology of single native membrane proteins with high resolution and,via single-molecule force spectroscopy(SMFS),directly measure their biophysical properties during molecular physiological activities such as ligand binding and protein unfolding.In the context of molecular biomechanics,SMFS has been successfully used to understand the structure and function of membrane proteins,complementing the static three-dimensional structures of proteins obtained by X-ray crystallography.Here,based on the authors’antigen-antibody binding force measurements in clinical tumor cells,the principle and method of SMFS is discussed,the progress in using SMFS to characterize membrane proteins is summarized,and challenges for SMFS are presented.展开更多
基金supported the National Natural Science Foundation of China(grant no.22001074 to L.Z.)the Natural Science Foundation of Shanghai(grant no.22ZR1479400 to L.Z.).
文摘Molecular machines transduce energy from one form to another through controlled motion in response to stimuli.Despite the ubiquitous use of molecular machines in biology,understanding the detailed mechanisms of such complex structures remains challenging.Recent progress in studying the modes of operation of synthetic small-molecule machines at the single-molecule level has shed new light on the mechanisms of nano-machinery.In this mini-review,we focus on the study of artificial small-molecule machines using single-molecule techniques,including single-molecule force spectroscopy,single-molecule electrical spectroscopy,and single-molecule optical spectroscopy.We survey the techniques used to monitor single-molecule behavior to date and describe the latest studies on small-molecule machines,highlighting their common features and challenges that need to be overcome to realize the potential of these techniques in unraveling the behavior of small molecule systems.
基金supported by the Natural Science Foundation of Guangdong Province,China(Grant No.2017A030310085)the Science and Technology Planning Project of Guangdong Province,China(Grant No.2018A050506034).
文摘The mechanical stability of tRNAs contributes to their biological activities.The mitochondrial tRNAArg from Romanomermis culicivorax is the shortest tRNA ever known.This tRNA lacks D-and T-arms,represents a stem-bulge-stem architecture but still folds into a stable tertiary structure.Although its structure had been reported,studies on its mechanical folding and unfolding kinetic characteristics are lacking.Here,we directly measured the single-molecule mechanical folding and unfolding kinetics of the armless mt tRNAArg by using optical tweezers in different solution conditions.We revealed a two-step reversible unfolding pathway:the first and large transition corresponds to the unfolding of acceptor stem and bulge below 11 pN,and the second and small transition corresponds to the unfolding of anticodon arm at 12 pN-14 pN.Moreover,the free energy landscapes of the unfolding pathways were reconstructed.We also demonstrated that amino acid-chelated Mg^(2+)(aaCM),which mimics the intracellular solution condition,stabilizes the bulge of mitochondrial tRNAArg possibly by reducing the topological constraints or stabilizing the possible local non-canonical base pairings within the bulge region.Our study revealed the solution-dependent mechanical stability of an armless mt tRNA,which may shed light on future mt tRNA studies.
基金supported by the National Natural Science Foundation of China (61175103)CAS FEA International Partnership Program for Creative Research Teams
文摘Membrane proteins are crucial in cell physiological activities and are the targets for most drugs.Thus,investigating the behaviors of membrane proteins not only provide deeper insights into cell function,but also help disease treatment and drug development.Atomic force microscopy is a unique tool for investigating the structure of membrane proteins.It can both image the morphology of single native membrane proteins with high resolution and,via single-molecule force spectroscopy(SMFS),directly measure their biophysical properties during molecular physiological activities such as ligand binding and protein unfolding.In the context of molecular biomechanics,SMFS has been successfully used to understand the structure and function of membrane proteins,complementing the static three-dimensional structures of proteins obtained by X-ray crystallography.Here,based on the authors’antigen-antibody binding force measurements in clinical tumor cells,the principle and method of SMFS is discussed,the progress in using SMFS to characterize membrane proteins is summarized,and challenges for SMFS are presented.
