High-level pacidamycin resistance in Pseudomonas aeruginosa is mediated by an opp oligopeptide permease encoded by the opp-fabI operon.
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OppA (609 aa, PA1811) and OppB (615 aa, PA1810) are the two Opp periplasmic binding proteins; the protein lengths match the PAO1 loci.
"OppA (609 amino acids) and OppB (615 amino acids) are closely related (42.5% identity in CLUSTALW alignments)"
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Both binding proteins are required for pacidamycin uptake and neither compensates for the other.
"This mutant analysis also indicated that both OppA and OppB periplasmic binding proteins were required for pacidamycin uptake and that they cannot compensate for each other."
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The Opp system transports the dipeptide PAbetaN, and transport is impaired in opp mutants.
"The Opp system was shown to be a bona fide oligopeptide transport system by demonstrating that transport of PAβN is impaired in opp mutants."
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OppA and OppB carry type I signal peptides and are predicted periplasmic binding proteins.
"The first two genes, oppA and oppB , whose coding sequences overlap, contain type I signal peptides; thus, they are probably periplasmic binding proteins."