title: The REC domain mediated dimerization is critical for FleQ from Pseudomonas aeruginosa to function as a c-di-GMP receptor and flagella gene regulator.
abstract: FleQ is an AAA+ ATPase enhancer-binding protein that regulates both flagella and biofilm formation in the opportunistic pathogen Pseudomonas aeruginosa. FleQ belongs to the NtrC subfamily of response regulators, but lacks the corresponding aspartic acid for phosphorylation in the REC domain (FleQ(R), also named FleQ domain). Here, we show that the atypical REC domain of FleQ is essential for the function of FleQ. Crystal structure of FleQ(R) at 2.3Å reveals that the structure of FleQ(R) is significantly different from the REC domain of NtrC1 which regulates gene expression in a phosphorylation dependent manner. FleQ(R) forms a novel active dimer (transverse dimer), and mediates the dimerization of full-length FleQ in an unusual manner. Point mutations that affect the dimerization of FleQ lead to loss of function of the protein. Moreover, a c-di-GMP binding site deviating from the previous reported one is identified through structure analysis and point mutations.
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China.
authors.forename: Tiantian
authors.initials: T
authors.lastname: Su
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China.
authors.forename: Shiheng
authors.initials: S
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China.
authors.forename: Kang
authors.initials: K
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China.
authors.forename: Kaikai
authors.initials: K
authors.lastname: Chi
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China.
authors.forename: Deyu
authors.initials: D
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China.
authors.forename: Tiandi
authors.initials: T
authors.lastname: Wei
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Rizhao Center for Diseases Prevention and Control, Rizhao Health Bureau, Rizhao 276826, Shandong, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China.
authors.forename: Sujuan
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Biotechnology and Biomedicine, Yangtze Delta Region Institute of Tsinghua University, Jiaxing, Zhejiang 314006, China.
authors.forename: Zong
authors.initials: Z
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China. Electronic address: lcgu@sdu.edu.cn.
authors.forename: Lichuan
authors.initials: L
authors.lastname: Gu
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000502:physiology; D001665:Binding Sites; D018441:Biofilms; D018360:Crystallography, X-Ray; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D008969:Molecular Sequence Data; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D015534:Trans-Activators / Q000737:chemistry* / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; C108098:FleQ protein, Pseudomonas aeruginosa; D015534:Trans-Activators; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP
keywords: Biofilm; Cyclic di-GMP; Flagella; Pseudomonas aeruginosa; Structure–function; Transcription factor