Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA.
J Bacteriol. 2013 Feb;195(4):765-76. doi: 10.1128/JB.01639-12. Epub 2012 Dec 7.
The soil bacterium Pseudomonas protegens Pf-5 (previously called P. fluorescens Pf-5) produces two siderophores, enantio-pyochelin and a compound in the large and diverse pyoverdine family. Using high-resolution mass spectroscopy, we determined the structure of the pyoverdine produced by Pf-5. In addition to producing its own siderophores, Pf-5 also utilizes ferric complexes of some pyoverdines produced by other strains of Pseudomonas spp. as sources of iron. Previously, phylogenetic analysis of the 45 TonB-dependent outer membrane proteins in Pf-5 indicated that six are in a well-supported clade with ferric-pyoverdine receptors (Fpvs) from other Pseudomonas spp. We used a combination of phylogenetics, bioinformatics, mutagenesis, pyoverdine structural determinations, and cross-feeding bioassays to assign specific ferric-pyoverdine substrates to each of the six Fpvs of Pf-5. We identified at least one ferric-pyoverdine that was taken up by each of the six Fpvs of Pf-5. Functional redundancy of the Pf-5 Fpvs was also apparent, with some ferric-pyoverdines taken up by all mutants with a single Fpv deletion but not by a mutant having deletions in two of the Fpv-encoding genes. Finally, we demonstrated that phylogenetically related Fpvs take up ferric complexes of structurally related pyoverdines, thereby establishing structure-function relationships that can be employed in the future to predict the pyoverdine substrates of Fpvs in other Pseudomonas spp.
土壤细菌荧光假单胞菌 Pf-5(以前称为荧光假单胞菌 Pf-5)产生两种铁载体,对映体-吡咯并并啉和一种在大型多样的吡咯并家族中的化合物。使用高分辨率质谱,我们确定了 Pf-5 产生的吡咯并的结构。除了产生自己的铁载体外,Pf-5 还利用其他假单胞菌菌株产生的铁复合物作为铁源。先前,对 Pf-5 中 45 个 TonB 依赖性外膜蛋白的系统发育分析表明,其中 6 个与其他假单胞菌的铁-吡咯并受体(Fpvs)在一个支持良好的分支中。我们使用系统发育学、生物信息学、诱变、吡咯并结构测定和交叉喂养生物测定的组合,将特定的铁-吡咯并底物分配给 Pf-5 的六个 Fpvs 中的每一个。我们确定了至少一种被 Pf-5 的六个 Fpvs 中的每一个吸收的铁-吡咯并。Pf-5 Fpvs 的功能冗余也很明显,一些铁-吡咯并被所有缺失单个 Fpv 的突变体吸收,但不能被缺失两个 Fpv 编码基因的突变体吸收。最后,我们证明了系统发育上相关的 Fpvs 吸收结构相关的吡咯并的铁复合物,从而建立了可以在未来用于预测其他假单胞菌 Fpvs 的吡咯并底物的结构-功能关系。