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The dipeptide permease of Escherichia coli closely resembles other bacterial transport systems and shows growth‐phase‐dependent expression
Author(s) -
Abouhamad Walid N.,
Manson Michael D.
Publication year - 1994
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1994.tb01340.x
Subject(s) - operon , permease , biology , escherichia coli , periplasmic space , lac operon , gene , start codon , transcription (linguistics) , bacillus subtilis , plasmid , trp operon , atp binding cassette transporter , biochemistry , microbiology and biotechnology , messenger rna , genetics , transporter , bacteria , linguistics , philosophy
Summary The dipeptide permease (Dpp) of Escherichia coli transports peptides consisting of two or three L‐amino acids. The periplasmic dipeptide‐binding protein (DBP), encoded by the dppA gene, also serves as a chemoreceptor. We sequenced the dpp locus, which comprises an operon of five genes, dppABCDE. Its organization is the same as the oligopeptide permease (opp) operon of Salmonella typhimurium and the spo0K operon of Bacillus subtilis. The dpp genes are also closely related to the hbpA gene, which encodes a haem‐hinding lipoprotein, and four other genes in an unlinked operon of unknown function in Haemophilus influenzae. Each Dpp protein has an Opp, Spo0K and H. influenzae homologue. Transcription of the dpp operon initiates 165 bases upstream of the predicted dppA start codon. The start site for transcription is preceded by potential −35 and −10 regions of a σ 70 promoter. During exponential growth in Luria‐Bertani (LB) broth, the level of dpp mRNA increases in two steps, one between A 590 0.2 and 0.4 and one between A 590 0.7 and 1.0. The 310 nucleotides between dppA and dppB include a RIP (repetitive IHF‐binding palindromic) element, whose deletion from a multi‐copy plasmid causes fivefold and 10‐fold reductions in the levels of upstream and downstream dpp mRNA, respectively.