CsgA protein monomers consist of aβ-helix of five repeat units possessing several conservative residues and thus,inherently fibrillate.CsgA protein monomers could self-assemble into hierarchical nanofiber structure c...CsgA protein monomers consist of aβ-helix of five repeat units possessing several conservative residues and thus,inherently fibrillate.CsgA protein monomers could self-assemble into hierarchical nanofiber structure cross multiple scales after expression and secretion by E.Coli cells.Previous researches show that CsgA nanofibers could provide adhesion,stiffness,and mechanical homogeneity for the biofilms,host cells’fibronectin binding for internalization,or protection against phage attack.CsgA nanofibers have obtained various applications in material science and synthetic biology.To illustrate,CsgA nanofibers have characteristics of intrinsic hierarchical structures across multiple scales,robustness in harsh environments and programmable functionality via biological tools.Studying the force spectrum or mechanical properties of the nanofiber can provide fundamental information of self-assembly process and ultra-stability in extreme conditions.Single molecule techniques such as atomic force microscopy,optical tweezers,and magnetic tweezers have been widely applied to study proteins.In these studies,proteins are usually chemically conjugated or genetically constructed to have a tag such as histidine,cysteine or biotin.Genetic engineering requires modification of the plasmids encoding the specific protein,and also involve special protein expression and purification.Such study needs collaboration from multi-disciplinary.It normally studies one protein at a time which gives out clear signal but lacks throughput and efficiency.Here we have established a simple method to measure all kinds of proteins without labels.The carboxyl terminus of a protein is attached to the amine group on a magnetic bead,and the amine terminus of the protein is attached to glutaraldehyde on the glass slide.Then we used magnetic tweezers to manipulate and stretched the bead and protein.Extension versus rotation relation was used to identify a single protein or protein fibril.The fiber under tension is also observed by Scanning Electronic Microcopy which convinces that single CsgA-His fibril is linked to a microbead.The peak of diameter distribution is around 15 nm.The fracture of fibers was observed in real time on SEM.Force-extension curves of single fibers are obtained in real time.The force-extension curves generally agree with the worm like chain model.The persistence lengths from the fitting are from 0.9 to 49.8 nm.The elongation ratio increases gradually with force until reaches a plateau.The maximum elongation ratio of 78 nanofibers were made into an elongation ratio distribution diagram,more than half of CsgA-His nanofibers has an elongation ratio from 0 to 2,some are distributed in 2~10,and a few are distributed in 10~18.The maximum elongation ratio of CsgA-His nanofibers is 17.1,indicating that the fibril’s flexibility is much higher than DNA or silk fiber.For forces less than 20 pN,the extension was reversible.With a 42.1 pN holding force,the extension jumped in steps of from 30 to 365 nm and was irreversible.At the scale tested,the jumps corresponded to the unfolding of multiple beta sheets in the fiber.Work for CsgA-His nanofibers during stretching increase with the normalized strain fractions.The experimental data agree with a theoretical prediction for a single CsgA protein from a SMD calculation.Therefore,our results provide key information for the understandings of CsgA protein nanofiber assembly and biofilm robustness.展开更多
Immune rejection, poor biocompatibility and cytotoxicity have seriously stalled the widespread application of biometallic materials. To overcome these problems, biometallic materials with fast and sufficient osseointe...Immune rejection, poor biocompatibility and cytotoxicity have seriously stalled the widespread application of biometallic materials. To overcome these problems, biometallic materials with fast and sufficient osseointegration, antibacterial properties and long-term stability have attracted the attention of researchers worldwide. Surface modification is currently used as a general strategy to develop material coatings that will overcome these challenging requirements and achieve the successful performance of implants. In this study, we proposed a substrate surface-modification strategy based on biofilm Csg A proteins that promote rapid cell attachment, proliferation, and stabilization of the cytoskeleton. Csg A-based nano-coating is easy to fabricate and has superior performance, which is expected to expand the application of medical implants.展开更多
以大肠杆菌菌毛蛋白CsgA组装形成的蛋白纤维为模板,引导不同数目的DNA四面体(tetrahedron DNA nanostructure,TDN)组装构建了蛋白-DNA亚微米复合结构. TDN经次氮基三乙酸(NTA)修饰后在Ni2+的螯合作用下与CsgA蛋白单体结合,利用CsgA的自...以大肠杆菌菌毛蛋白CsgA组装形成的蛋白纤维为模板,引导不同数目的DNA四面体(tetrahedron DNA nanostructure,TDN)组装构建了蛋白-DNA亚微米复合结构. TDN经次氮基三乙酸(NTA)修饰后在Ni2+的螯合作用下与CsgA蛋白单体结合,利用CsgA的自组装能力将TDN有序地排列在形成的蛋白纤维上.原子力显微镜(atomic force microscopy,AFM)成像结果表明,控制TDN与CsgA的浓度比为1:500,可以得到单个TDN与蛋白纤维的组装产物.将2个TDN通过杂交形成二聚体(dTDN)与CsgA蛋白进行组装,得到的亚微米复合结构保持了很好的直链形态,在蛋白纤维上连有3个dTDN结构的比例达44%.展开更多
基金supported by the National Science Foundation of China ( 11772133, 11372116)
文摘CsgA protein monomers consist of aβ-helix of five repeat units possessing several conservative residues and thus,inherently fibrillate.CsgA protein monomers could self-assemble into hierarchical nanofiber structure cross multiple scales after expression and secretion by E.Coli cells.Previous researches show that CsgA nanofibers could provide adhesion,stiffness,and mechanical homogeneity for the biofilms,host cells’fibronectin binding for internalization,or protection against phage attack.CsgA nanofibers have obtained various applications in material science and synthetic biology.To illustrate,CsgA nanofibers have characteristics of intrinsic hierarchical structures across multiple scales,robustness in harsh environments and programmable functionality via biological tools.Studying the force spectrum or mechanical properties of the nanofiber can provide fundamental information of self-assembly process and ultra-stability in extreme conditions.Single molecule techniques such as atomic force microscopy,optical tweezers,and magnetic tweezers have been widely applied to study proteins.In these studies,proteins are usually chemically conjugated or genetically constructed to have a tag such as histidine,cysteine or biotin.Genetic engineering requires modification of the plasmids encoding the specific protein,and also involve special protein expression and purification.Such study needs collaboration from multi-disciplinary.It normally studies one protein at a time which gives out clear signal but lacks throughput and efficiency.Here we have established a simple method to measure all kinds of proteins without labels.The carboxyl terminus of a protein is attached to the amine group on a magnetic bead,and the amine terminus of the protein is attached to glutaraldehyde on the glass slide.Then we used magnetic tweezers to manipulate and stretched the bead and protein.Extension versus rotation relation was used to identify a single protein or protein fibril.The fiber under tension is also observed by Scanning Electronic Microcopy which convinces that single CsgA-His fibril is linked to a microbead.The peak of diameter distribution is around 15 nm.The fracture of fibers was observed in real time on SEM.Force-extension curves of single fibers are obtained in real time.The force-extension curves generally agree with the worm like chain model.The persistence lengths from the fitting are from 0.9 to 49.8 nm.The elongation ratio increases gradually with force until reaches a plateau.The maximum elongation ratio of 78 nanofibers were made into an elongation ratio distribution diagram,more than half of CsgA-His nanofibers has an elongation ratio from 0 to 2,some are distributed in 2~10,and a few are distributed in 10~18.The maximum elongation ratio of CsgA-His nanofibers is 17.1,indicating that the fibril’s flexibility is much higher than DNA or silk fiber.For forces less than 20 pN,the extension was reversible.With a 42.1 pN holding force,the extension jumped in steps of from 30 to 365 nm and was irreversible.At the scale tested,the jumps corresponded to the unfolding of multiple beta sheets in the fiber.Work for CsgA-His nanofibers during stretching increase with the normalized strain fractions.The experimental data agree with a theoretical prediction for a single CsgA protein from a SMD calculation.Therefore,our results provide key information for the understandings of CsgA protein nanofiber assembly and biofilm robustness.
基金supported by the National Natural Science Foundation of China (Nos. 82104477, U19A2010, and 81891012)special support from China Postdoctoral Science Foundation(Nos. 2019M663456 and 2019TQ0044)+4 种基金Xinglin Scholar Research Promotion Project of Chengdu University of TCM (No.BSH_(2)019008)National Interdisciplinary Innovation Team of Traditional Chinese Medicine (No. ZYYCXTD-D-202209)the Macao Science and Technology Development Fund (No. FDCT 007/2020/ALC)the Shenzhen-Hong Kong-Macao S&T Program (Category C)(No. SGDX2020110309420200)the Research Fund of University of Macao (No. CPG2022-00005-ICMS)。
文摘Immune rejection, poor biocompatibility and cytotoxicity have seriously stalled the widespread application of biometallic materials. To overcome these problems, biometallic materials with fast and sufficient osseointegration, antibacterial properties and long-term stability have attracted the attention of researchers worldwide. Surface modification is currently used as a general strategy to develop material coatings that will overcome these challenging requirements and achieve the successful performance of implants. In this study, we proposed a substrate surface-modification strategy based on biofilm Csg A proteins that promote rapid cell attachment, proliferation, and stabilization of the cytoskeleton. Csg A-based nano-coating is easy to fabricate and has superior performance, which is expected to expand the application of medical implants.
文摘以大肠杆菌菌毛蛋白CsgA组装形成的蛋白纤维为模板,引导不同数目的DNA四面体(tetrahedron DNA nanostructure,TDN)组装构建了蛋白-DNA亚微米复合结构. TDN经次氮基三乙酸(NTA)修饰后在Ni2+的螯合作用下与CsgA蛋白单体结合,利用CsgA的自组装能力将TDN有序地排列在形成的蛋白纤维上.原子力显微镜(atomic force microscopy,AFM)成像结果表明,控制TDN与CsgA的浓度比为1:500,可以得到单个TDN与蛋白纤维的组装产物.将2个TDN通过杂交形成二聚体(dTDN)与CsgA蛋白进行组装,得到的亚微米复合结构保持了很好的直链形态,在蛋白纤维上连有3个dTDN结构的比例达44%.
