Regulation of constant cell elongation and Sfm pili synthesis in Escherichia coli via two active forms of FimZ orphan response regulator

• Published in: Genes to cells : devoted to molecular & cellular mechanisms Vol. 27; no. 11; pp. 657 - 674
• Main Authors: Ogawa, Ayano, Kojima, Fumika, Miyake, Yukari, Yoshimura, Miho, Ishijima, Nozomi, Iyoda, Sunao, Sekine, Yasuhiko, Yamanaka, Yuki, Yamamoto, Kaneyoshi
• Format: Journal Article
• Language: English
• Published: Tokyo Wiley Subscription Services, Inc 01.11.2022
• Subjects: Amino acids; chaperone‐usher pili; Chromatin; E coli; Elongation; Escherichia coli; fimbriae; FimZ response regulator; Immunoprecipitation; Operons; Phosphorylation; Pili; sfm operon; Transcriptomes
• ISSN: 1356-9597; 1365-2443
• DOI: 10.1111/gtc.12982

Escherichia coli (E. coli) has multiple copies of the chaperone‐usher (CU) pili operon in five fimbria groups: CU pili, curli, type IV pili, type III secretion pili, and type IV secretion pili. Commensal E. coli K‐12 contains 12 CU pili operons. Among these operons, Sfm is expressed by the sfmACDHF operon. Transcriptome analyses, reporter assays, and chromatin immunoprecipitation PCR analyses reported that FimZ directly binds to and activates the sfmA promoter, transcribing sfmACDHF. In addition, FimZ regularly induces constant cell elongation in E. coli, which is required for F‐type ATPase function. The bacterial two‐hybrid system showed a specific interaction between FimZ and the α subunit of the cytoplasmic F1 domain of F‐type ATPase. Studies performed using mutated FimZs have revealed two active forms, I and II. Active form I is required for constant cell elongation involving amino acid residues K106 and D109. Active form II additionally required D56, a putative phosphorylation site, to activate the sfmA promoter. The chromosomal fimZ was hardly expressed in parent strain but functioned in phoB and phoP double‐gene knockout strains. These insights may help to understand bacterial invasion restricted host environments by the sfm γ‐type pili. Escherichia coli (E. coli) orphan response regulator FimZ has two active forms, I and II. The active form I induces a constant elongation and the active form II induce the expression of sfm operon. Sequential regulation by FimZ could make an elongated E. coli with Sfm pilli.