TonB-dependent Transporters of Fe-petrobactin in Marinobacter nauticus and Southern Ocean bacteria
- 1IPREM: Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les Materiaux
Abstract
TonB-dependent transporters (TBDTs) play a central role in siderophore-mediated iron acquisition in the marine environment. However, assigning substrate specificity to TBDTs remains a major bottleneck in understanding the ecological and mechanistic roles of siderophore production and uptake. Here, we identify in Marinobacter nauticus two TBDTs, OptA and OptB, that share low sequence identity yet both mediate Fe-petrobactin uptake. Despite this functional overlap, they underlie distinct regulatory mechanisms, suggesting differential utilization under specific environmental conditions. Phylogenetic analyses indicate that OptA likely co-evolved with the petrobactin biosynthetic gene cluster, whereas OptB appears to have followed a distinct evolutionary trajectory, acquiring the capacity to import petrobactin as a xenosiderophore. Using resuscitated communities from the Southern Ocean, we further show that Fe-petrobactin stimulated prokaryotic growth. Based on amino acid similarity, we identified OptB-like transporters encoded in metagenomes and MAGs and show that taxa harbouring these transporters, such as Pseudoaltermonas, respond specifically to Fe-petrobactin addition. OptB-like transporters were also detected in environmental metagenomes from the Southern Ocean, whereas the petrobactin biosynthetic gene clusters were not, indicating that petrobactin primarily functions as a xenosiderophore in natural communities.
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BibTeX
@misc{nolivos2026tonbdependent,
title = {{TonB-dependent Transporters of Fe-petrobactin in Marinobacter nauticus and Southern Ocean bacteria}},
author = {S. Nolivos and R. Thoppil and F. Hakil and A. Gueneugues and P. Catala and K. Kinska and R. Lobinski and S. Blain and I. Obernosterer and R. Grimaud},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.08.756784},
url = {https://www.biorxiv.org/content/10.64898/2026.10.08.756784v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - TonB-dependent Transporters of Fe-petrobactin in Marinobacter nauticus and Southern Ocean bacteria
AU - S. Nolivos
AU - R. Thoppil
AU - F. Hakil
AU - A. Gueneugues
AU - P. Catala
AU - K. Kinska
AU - R. Lobinski
AU - S. Blain
AU - I. Obernosterer
AU - R. Grimaud
PY - 2026
DA - 2026/10/08
PB - bioRxiv
DO - 10.64898/2026.10.08.756784
UR - https://www.biorxiv.org/content/10.64898/2026.10.08.756784v1
AB - TonB-dependent transporters (TBDTs) play a central role in siderophore-mediated iron acquisition in the marine environment. However, assigning substrate specificity to TBDTs remains a major bottleneck in understanding the ecological and mechanistic roles of siderophore production and uptake. Here, we identify in Marinobacter nauticus two TBDTs, OptA and OptB, that share low sequence identity yet both mediate Fe-petrobactin uptake. Despite this functional overlap, they underlie distinct regulatory mechanisms, suggesting differential utilization under specific environmental conditions. Phylogenetic analyses indicate that OptA likely co-evolved with the petrobactin biosynthetic gene cluster, whereas OptB appears to have followed a distinct evolutionary trajectory, acquiring the capacity to import petrobactin as a xenosiderophore. Using resuscitated communities from the Southern Ocean, we further show that Fe-petrobactin stimulated prokaryotic growth. Based on amino acid similarity, we identified OptB-like transporters encoded in metagenomes and MAGs and show that taxa harbouring these transporters, such as Pseudoaltermonas, respond specifically to Fe-petrobactin addition. OptB-like transporters were also detected in environmental metagenomes from the Southern Ocean, whereas the petrobactin biosynthetic gene clusters were not, indicating that petrobactin primarily functions as a xenosiderophore in natural communities.
ER -