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Iron‐Mediated Regulation of Alkaline Proteinase Production in Pseudomonas aeruginosa
Author(s) -
Shigematsu Takashi,
Fukushima Jun,
Oyama Masatsune,
Tsuda Masataka,
Kawamoto Susumu,
Okuda Kenji
Publication year - 2001
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2001.tb01289.x
Subject(s) - psychological repression , transferrin , biology , primer extension , enzyme repression , sigma factor , microbiology and biotechnology , mutant , pseudomonas aeruginosa , transcription (linguistics) , biochemistry , protein biosynthesis , gene expression , gene , messenger rna , bacteria , promoter , genetics , linguistics , philosophy
We analyzed the regulation by iron of alkaline proteinase (AP) production in Pseudomonas aeruginosa . Extracellular AP production was detected from the mid‐logarithmic to the stationary phase by an antibody‐based assay system, and was strongly repressed by iron in the medium. This repression was shown by Northern hybridization and primer extension to occur at the level of transcription. The primer extension analysis revealed that the start point of transcription of AP gene was the nucleotide position −84 from the start point of translation. Furthermore, we investigated whether this transcriptional repression involved PvdS protein. Using the mutant strain of pvdS , the alternative σ factor gene revealed that the PvdS protein is required for the full expression of AP, and a previous study showed that expression of pvdS is also repressed by iron. Therefore, we thought that one mechanism of repression of AP production operated through reduction of the PvdS protein level. Purified AP decomposed the transferrin, and released iron from it Purified AP added to the medium containing transferrin as the only iron source enhanced the growth of P. aeruginosa . Moreover, mutation in the AP gene decreased the growth rate in the medium containing the transferrin as the only iron source. These results clearly indicated that AP expression should occur in a free‐iron‐deficient environment and emphasized the importance of AP to iron acquisition in the infection site.