Dataset Information

Probing Changes in Ca2+-Induced Interaction Forces between Calmodulin and Melittin by Atomic Force Microscopy.

ABSTRACT: Mechanobiology studies the means by which physical forces and mechanical properties change intra- or inter- biological macromolecules. Calmodulin (CaM) is involved in physiological activities and various metabolic processes in eukaryotic cells. Although the configuration changes in the interaction between calmodulin and melittin have been studied, the biomechanical relationship of their interaction has rarely been explored. Here, we measured the adhesion forces between calmodulin and melittin in solutions of gradient concentration of calcium ions using atomic force microscopy (AFM). We found that the specific (Fi) and nonspecific (F0) adhesion forces between single melittin and calmodulin in a PBS solution were 69.4 ± 5.0 and 29.3 ± 8.9 pN, respectively. In the presence of 10-7 to 10-3 M Ca2+ PBS solution, the Fi increased significantly to 93.8 ± 5.0, 139.9 ± 9.0, 140.4 ± 9.7, 171.5 ± 9.0, and 213.3 ± 17.8 pN, indicating that the unbinding force between melittin and calmodulin increased in the presence of Ca2+ in a concentration-dependent manner. These findings demonstrated that biomechanical studies based on AFM could help us better understand the melittin/calmodulin-binding processes in the presence of calcium and help us design and screen peptide drugs based on calmodulin.

SUBMITTER: Huang S

PROVIDER: S-EPMC7601158 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Probing Changes in Ca<sup>2+</sup>-Induced Interaction Forces between Calmodulin and Melittin by Atomic Force Microscopy.

Huang Sheng S Wang Jianhua J Sun Heng H Fu Yuna Y Wang Yan Y

Micromachines 20200930 10

Mechanobiology studies the means by which physical forces and mechanical properties change intra- or inter- biological macromolecules. Calmodulin (CaM) is involved in physiological activities and various metabolic processes in eukaryotic cells. Although the configuration changes in the interaction between calmodulin and melittin have been studied, the biomechanical relationship of their interaction has rarely been explored. Here, we measured the adhesion forces between calmodulin and melittin in ...[more]

PMID: 33007824

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Project description:BACKGROUND: Lignin is a complex polymer which inhibits the enzymatic conversion of cellulose to glucose in lignocellulose biomass for biofuel production. Cellulase enzymes irreversibly bind to lignin, deactivating the enzyme and lowering the overall activity of the hydrolyzing reaction solution. Within this study, atomic force microscopy (AFM) is used to compare the adhesion forces between cellulase and lignin with the forces between cellulase and cellulose, and to study the moiety groups involved in binding of cellulase to lignin. RESULTS: Trichoderma reesei, ATCC 26921, a commercial cellulase system, was immobilized onto silicon wafers and used as a substrate to measure forces involved in cellulase non-productive binding to lignin. Attraction forces between cellulase and lignin, and between cellulase and cellulose were compared using kraft lignin- and hydroxypropyl cellulose-coated tips with the immobilized cellulase substrate. The measured adhesion forces between kraft lignin and cellulase were on average 45% higher than forces between hydroxypropyl cellulose and cellulase. Specialized AFM tips with hydrophobic, -OH, and -COOH chemical characteristics were used with immobilized cellulase to represent hydrophobic, H-bonding, and charge-charge interactions, respectively. Forces between hydrophobic tips and cellulase were on average 43% and 13% higher than forces between cellulase with tips exhibiting OH and COOH groups, respectively. A strong attractive force during the AFM tip approach to the immobilized cellulase was observed with the hydrophobic tip. CONCLUSIONS: This work shows that there is a greater overall attraction between kraft lignin and cellulase than between hydroxypropyl cellulose and cellulase, which may have implications during the enzymatic reaction process. Furthermore, hydrophobic interactions appear to be the dominating attraction force in cellulase binding to lignin, while a number of other interactions may establish the irreversible binding.

Dataset Information

Probing Changes in Ca2+-Induced Interaction Forces between Calmodulin and Melittin by Atomic Force Microscopy.

Publications

Probing Changes in Ca<sup>2+</sup>-Induced Interaction Forces between Calmodulin and Melittin by Atomic Force Microscopy.

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