Outer membrane proteins mediate unconventional secretion of Pseudomonas peroxidase through crosstalk between the Sec pathway and outer membrane vesicles
- 1Institute of Marine Science and Technology, Shandong University, Qingdao, China
- 2Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- 3Shandong Key Laboratory of Intelligent Marine Engineering Geology, Environment and Equipment, Qingdao, China
Abstract
Lipoprotein and OmpW are two major components of the outer membrane (OM) in Gram-negative bacteria and play essential roles in various physiological processes, e.g., protein secretion, folding, and localization. They typically assist in maintaining client proteins in a folded state or form pore channels during secretion. However, how OM proteins facilitate the secretion of proteins that lack classical signal peptides remains elusive. Here, we demonstrate that they contribute to the secretion of unconventional B-type dye-decolorizing peroxidase (DypB2985) in Pseudomonas putida. The lipoprotein, Lpp1528, which contains a Sec signal peptide, is translocated to the periplasm through the Sec pathway and anchored in the inner leaflet of the OM. Lpp1528 recognizes the C-terminal hydrophobic region of DypB2985 in the cytoplasm and facilitates its coupling to the Sec machinery for inner membrane translocation, despite DypB2985 lacking a canonical N-terminal Sec signal peptide. Following translocation, the two proteins appear to dissociate in the periplasm. Subsequently, another OM protein, OmpW4836, recognizes the N-terminal hydrophobic region of periplasmic DypB2985 and mediates its incorporation into outer membrane vesicles (OMVs) for extracellular delivery. Our study reveals the crosstalk between the Sec pathway and OMVs in the secretion of a non-canonical peroxidase, in which OM proteins, acting as the molecular tethers, mediate the stepwise secretion process. It expands our understanding of non-classical protein secretion mechanisms and bacterial survival strategies. Moreover, the identified OMV sorting mechanism offers potential for the further functionalization of OMVs as versatile biotechnological platforms. Author summary: Bacterial protein secretion is a fundamental physiological process. Proteins commonly contain signal peptides and are exported via classical secretory pathways. However, some proteins without any characterized signal sequences can also leave the cytoplasm and be transported across cell membranes, posing a major unresolved question in the field. Here, we provide insights into the secretion of unconventional B-type dye-decolorizing peroxidases (DypB2985) in Pseudomonas putida. The lipoprotein, Lpp1528, identifies DypB2985 in the cytoplasm and targets it to the Sec secretion components, which transport DypB2985 across the inner membrane. Subsequently, another outer membrane protein, OmpW4836, recognizes periplasmic DypB2985 and mediates its sorting into OMVs for extracellular delivery. Overall, this study advances the understanding of non-classical protein secretion pathways and the inclusion sorting mechanism of OMVs, raising the possibility for the development of tailored biocatalytic and delivery platforms.
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BibTeX
@article{liang2026outer,
title = {{Outer membrane proteins mediate unconventional secretion of Pseudomonas peroxidase through crosstalk between the Sec pathway and outer membrane vesicles}},
author = {Congying Liang and Wenping Zhu and Lu Lin},
journal = {PLOS Genetics},
year = {2026},
month = sep,
doi = {10.1371/journal.pgen.1012311},
url = {https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1012311},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Outer membrane proteins mediate unconventional secretion of Pseudomonas peroxidase through crosstalk between the Sec pathway and outer membrane vesicles
AU - Congying Liang
AU - Wenping Zhu
AU - Lu Lin
PY - 2026
DA - 2026/09/15
JO - PLOS Genetics
DO - 10.1371/journal.pgen.1012311
UR - https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1012311
AB - Lipoprotein and OmpW are two major components of the outer membrane (OM) in Gram-negative bacteria and play essential roles in various physiological processes, e.g., protein secretion, folding, and localization. They typically assist in maintaining client proteins in a folded state or form pore channels during secretion. However, how OM proteins facilitate the secretion of proteins that lack classical signal peptides remains elusive. Here, we demonstrate that they contribute to the secretion of unconventional B-type dye-decolorizing peroxidase (DypB2985) in Pseudomonas putida. The lipoprotein, Lpp1528, which contains a Sec signal peptide, is translocated to the periplasm through the Sec pathway and anchored in the inner leaflet of the OM. Lpp1528 recognizes the C-terminal hydrophobic region of DypB2985 in the cytoplasm and facilitates its coupling to the Sec machinery for inner membrane translocation, despite DypB2985 lacking a canonical N-terminal Sec signal peptide. Following translocation, the two proteins appear to dissociate in the periplasm. Subsequently, another OM protein, OmpW4836, recognizes the N-terminal hydrophobic region of periplasmic DypB2985 and mediates its incorporation into outer membrane vesicles (OMVs) for extracellular delivery. Our study reveals the crosstalk between the Sec pathway and OMVs in the secretion of a non-canonical peroxidase, in which OM proteins, acting as the molecular tethers, mediate the stepwise secretion process. It expands our understanding of non-classical protein secretion mechanisms and bacterial survival strategies. Moreover, the identified OMV sorting mechanism offers potential for the further functionalization of OMVs as versatile biotechnological platforms. Author summary: Bacterial protein secretion is a fundamental physiological process. Proteins commonly contain signal peptides and are exported via classical secretory pathways. However, some proteins without any characterized signal sequences can also leave the cytoplasm and be transported across cell membranes, posing a major unresolved question in the field. Here, we provide insights into the secretion of unconventional B-type dye-decolorizing peroxidases (DypB2985) in Pseudomonas putida. The lipoprotein, Lpp1528, identifies DypB2985 in the cytoplasm and targets it to the Sec secretion components, which transport DypB2985 across the inner membrane. Subsequently, another outer membrane protein, OmpW4836, recognizes periplasmic DypB2985 and mediates its sorting into OMVs for extracellular delivery. Overall, this study advances the understanding of non-classical protein secretion pathways and the inclusion sorting mechanism of OMVs, raising the possibility for the development of tailored biocatalytic and delivery platforms.
SN - 1553-7404
ER -