The critical roles of polyamines in regulating ColE7 production and restricting ColE7 uptake of the colicin-producing Escherichia coli.
The ColE7 operon is an SOS response regulon, which encodes bacteriocin ColE7 to kill susceptible Escherichia coli and its related enterobacteria under conditions of stress. We have observed for the first time that polyamines confer limited resistance against ColE7 on E. coli cells. Thus, this study aims to investigate the role of polyamines in modulating the protective effect of the E. coli cells against colicin. In the experiments, we surprisingly found that endogenous polyamines are also essential for ColE7 production, and the rate of polyamine synthesis is directly related to the SOS response. Our experimental results further indicated that exogenous polyamines suppress the expression of TolA, BtuB, OmpF, and OmpC proteins that are responsible for ColE7 uptake. Moreover, two-dimensional gel electrophoresis revealed that the production of two periplasmic proteins, PotD and OppA, is increased in E. coli cells under ColE7 exposure. Based on these observations, we propose that endogenous polyamines may play a dual role in the ColE7 system. Polyamines may participate in initiating the expression of the SOS response of the ColE7 operon and simultaneously down-regulate proteins that are essential for colicin uptake, thus conferring a survival advantage on colicin-producing E. coli under stress conditions in the natural environment.
Institute of Biochemistry, National Yang Ming University, Taipei 11221, Taiwan.
Yi-Hsuan
YH
Pan
Institute of Biochemistry, National Yang Ming University, Taipei 11221, Taiwan.
Chen-Chung
CC
Liao
Institute of Bioengineering, Tatung University, Taipei 10452, Taiwan.
Chou-Chiang
CC
Kuo
Institute of Bioengineering, Tatung University, Taipei 10452, Taiwan.
Kow-Jen
KJ
Duan
Institute of Biological Chemistry, Taipei 1529, Taiwan.
Po-Huang
PH
Liang
Molecular Biology, Academic Sinica, Taipei 1529, Taiwan.
Hanna S
HS
Yuan
Institute of Microbiology and Immunology, National Yang Ming University, Taipei 11221, Taiwan.
Shiau-Ting
ST
Hu
Institute of Biochemistry, National Yang Ming University, Taipei 11221, Taiwan. Electronic address: kfchak@ym.edu.tw.
Kin-Fu
KF
Chak
D002352:Carrier Proteins / Q000378:metabolism; D003087:Colicins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008074:Lipoproteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism; D033902:Periplasmic Binding Proteins / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism*; D021381:Protein Transport
D002352:Carrier Proteins; C508089:ColE7 protein, E coli; D003087:Colicins; D029968:Escherichia coli Proteins; D008074:Lipoproteins; D026901:Membrane Transport Proteins; C499290:OppA protein, E coli; D033902:Periplasmic Binding Proteins; D011073:Polyamines; C099274:PotD protein, E coli