Investigating interactions of the Bacillus subtilis spore coat proteins CotY and CotZ using single molecule force spectroscopy.
Spores formed by Bacillus subtilis are surrounded by a protective and multilayered shell, termed the coat, which grants the spores resistance to various environmental stresses and facilitates spore germination. The spore coat consists of more than seventy different proteins, arranged into at least four distinct structural layers: the undercoat, inner coat, outer coat and crust. However, how these proteins, especially the morphogenetic proteins, interact to establish the organized, functional coat layers remains poorly understood. CotY and CotZ as the components of the crust, play a morphogenetic role in the crust assembly around the spore. In this study, the single molecule force spectroscopy was used to investigate the interaction and dynamics between CotY and CotZ at the single-molecule level. The results show that homotypic interactions of CotY and CotZ and the heterotypic interaction between CotY and CotZ exist. Furthermore, the dissociation kinetics of the complexes were studied by monitoring the relationship between the unbinding forces and the loading rates at different pulling velocities. In this way, a series of kinetic parameters regarding the three different complexes were obtained. It revealed the strong interactions between CotY and CotZ, CotY and CotY, and a relatively weak interaction of CotZ and CotZ.
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
Institute of Molecular Biology, Slovak Academy of Sciences, Dubravska cesta 21, 84551 Bratislava, 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, 84551 Bratislava, 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 / Q000502:physiology*; D001426:Bacterial Proteins / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D013171:Spores, Bacterial / Q000737:chemistry
D001426:Bacterial Proteins
Atomic force microscopy; CotY; CotZ; Protein–protein interaction; Single molecule force spectroscopy