Physical interaction and assembly of Bacillus subtilis spore coat proteins CotE and CotZ studied by atomic force microscopy.
The spore of Bacillus subtilis, a dormant type of cell, is surrounded by a complex multilayered protein structure known as the coat. It is composed of over 70 proteins and essential for the spore to withstand extreme environmental conditions and allow germination under favorable conditions. However, understanding how the properties of the coat arise from the interactions among all these proteins is an important challenge. Moreover, many specific protein-protein interactions among the coat proteins are crucial for coat assembly. In this study, atomic force microscopy (AFM) based single molecule force spectroscopy (SMFS) was applied to investigate the interaction as a dynamic process between two morphogenetic coat proteins, CotE and CotZ. The unbinding force and kinetic parameters characterizing the interaction between CotE and CotZ were obtained. It is found that there is a strong affinity between CotE and CotZ. Furthermore, the assembly behaviors of CotE and CotZ, individually or in combination, were studied by AFM at solid-liquid interfaces. Our results revealed that CotE-CotZ assembly is dependent on their molar ratios and the interaction between CotE and CotZ involves in the CotE-CotZ assembly.
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
Huiqing
H
Liu
College of Chemistry, Chemical Engineering and Environmental Engineering, Liaoning University of Petroleum & Chemical Technology, Fushun 113001, PR China.
Haiyan
H
Qiao
Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, Bratislava 845 51, Slovakia.
Daniela
D
Krajcikova
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China.
Zhe
Z
Zhang
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China.
Hongda
H
Wang
Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, Bratislava 845 51, Slovakia.
Imrich
I
Barak
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China. Electronic address: jltang@ciac.ac.cn.
Jilin
J
Tang
D001412:Bacillus subtilis / Q000737:chemistry* / Q000648:ultrastructure; D001426:Bacterial Proteins / Q000737:chemistry* / Q000648:ultrastructure; D002473:Cell Wall / Q000737:chemistry / Q000648:ultrastructure; D007700:Kinetics; D018625:Microscopy, Atomic Force; D009024:Morphogenesis; D013171:Spores, Bacterial / Q000737:chemistry* / Q000648:ultrastructure
D001426:Bacterial Proteins; C077494:CotE protein, Bacillus subtilis
Atomic force microscopy; CotE; CotZ; Protein–protein interaction; Self-assembly; Single molecule force spectroscopy