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Nucleotide sequence analysis and potential environmental distribution of a ferric pseudobactin receptor gene of
J Morris1, D F Donnelly, E O'Neill
1Microbiology Department, University College, Cork, Ireland.
Abstract:
The nucleotide sequence of the Pseudomonas sp. strain M114 pbuA gene, encoding the outer membrane receptor for ferric pseudobactin M114, has been determined. The region sequenced spans 2788 bases of plasmid pCUP3, within which the receptor gene had previously been localised. A single open reading frame, potentially encoding 826 amino acids and including a leader peptide of 44 amino acids, is evident and is followed by an inverted repeat segment, which may act as a transcriptional terminator. A 20 bp region of DNA, having significant homology with the E. coli Fur-binding consensus sequence, is located upstream of the open reading frame. PbuA displays characteristics in common with other outer membrane proteins and displays strong homology with the TonB boxes of both E. coli and Pseudomonas receptors. More extensive homologies were found with the PupA receptor of P. putida WCS358 and the FhuE and BtuB receptors of E. coli. It is suggested that areas exhibiting the least homology between these receptors may represent ferric siderophore-specific recognition sites of the PbuA protein. The deduced amino acid sequence of pbuA was compared with that of pupX, encoding the outer membrane receptor for ferric pseudobactin B10, of Pseudomonas sp. strain B 10. A direct alignment of the two proteins gave an identity score of 92.5%. The distribution of PbuA-like receptors among Pseudomonas isolates was investigated by DNA-DNA hybridisation analysis. The results suggest that a PbuA-like receptor may be widely distributed among Pseudomonas rhizosphere isolates.
Insights
The Pseudomonas sp. strain M114 pbuA gene encodes an outer membrane receptor for ferric pseudobactin. This receptor shows significant homology to other bacterial receptors, suggesting a widespread distribution among Pseudomonas isolates.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Pseudomonas species utilize outer membrane receptors for iron uptake via siderophores.
- Ferric pseudobactin M114 is a siderophore crucial for iron acquisition in Pseudomonas sp. strain M114.
- The pbuA gene encodes the outer membrane receptor for ferric pseudobactin M114.
Purpose of the Study:
- To determine the nucleotide sequence of the Pseudomonas sp. strain M114 pbuA gene.
- To analyze the genetic features and homology of the PbuA receptor.
- To investigate the distribution of PbuA-like receptors in Pseudomonas isolates.
Main Methods:
- DNA sequencing of plasmid pCUP3.
- Bioinformatic analysis of the open reading frame and regulatory regions.
- Comparison of PbuA sequence with known outer membrane receptors.
- DNA-DNA hybridization analysis.
Main Results:
- The pbuA gene sequence was determined, revealing a potential 826-amino acid protein with a leader peptide.
- A putative transcriptional terminator and a Fur-binding consensus sequence were identified upstream.
- PbuA exhibits homology to TonB boxes and shares significant similarity with other bacterial receptors, particularly PupX (92.5% identity).
- DNA-DNA hybridization indicates a widespread presence of PbuA-like receptors in Pseudomonas rhizosphere isolates.
Conclusions:
- The PbuA receptor sequence provides insights into ferric siderophore recognition mechanisms.
- Homology analysis suggests conserved functional domains among bacterial outer membrane receptors.
- PbuA-like receptors are likely common in Pseudomonas rhizosphere populations, facilitating iron acquisition.