The ferric-pseudobactin receptor PupA of Pseudomonas putida WCS358: homology to TonB-dependent Escherichia coli receptors and specificity of the protein

• Published in: Molecular microbiology Vol. 5; no. 3; p. 647
• Main Authors: Bitter, W, Marugg, J D, de Weger, L A, Tommassen, J, Weisbeek, P J
• Format: Journal Article
• Language: English
• Published: England 01.03.1991
• Subjects: Amino Acid Sequence; Bacterial Outer Membrane Proteins - chemistry; Bacterial Outer Membrane Proteins - genetics; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Base Sequence; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins; Ferric Compounds - metabolism; Genes, Bacterial; Membrane Proteins - genetics; Membrane Proteins - metabolism; Membrane Transport Proteins; Molecular Sequence Data; Mutation; Oligopeptides - metabolism; Open Reading Frames; Protein Sorting Signals; Pseudomonas - genetics; Pseudomonas - metabolism; Receptors, Cell Surface - chemistry; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Receptors, Peptide; Receptors, Virus
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.1991.tb00736.x

The initial step in the uptake of iron via ferric pseudobactin by the plant-growth-promoting Pseudomonas putida strain WCS358 is binding to a specific outer-membrane protein. The nucleotide sequence of the pupA structural gene, which codes for a ferric pseudobactin receptor, was determined. It contains a single open reading frame which potentially encodes a polypeptide of 819 amino acids, including a putative N-terminal signal sequence of 47 amino acids. Significant homology, concentrated in four boxes, was found with the TonB-dependent receptor proteins of Escherichia coli. The pupA mutant MH100 showed a residual efficiency of 30% in the uptake of 55Fe3+ complexed to pseudobactin 358, whereas the iron uptake of four other pseudobactins was not reduced at all. Cells of strain WCS374 supplemented with the pupA gene of strain WCS358 could transport ferric pseudobactin 358 but showed no affinity for three other pseudobactins. It is concluded that PupA is a specific receptor for ferric pseudobactin 358, and that strain WCS358 produces at least one other receptor for other pseudobactins.