Myxosortase: an intramembrane protease that sorts MYXO-CTERM proteins to the cell surface
ABSTRACT Cell surface proteins determine how cells interact with their biotic and abiotic environments. In social myxobacteria, a C-terminal protein sorting tag called MYXO-CTERM is universally found within the Myxococcota phylum, where their genomes typically contain dozens of proteins with this mo...
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
American Society for Microbiology
2025-04-01
|
| Series: | mBio |
| Subjects: | |
| Online Access: | https://journals.asm.org/doi/10.1128/mbio.04067-24 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850185432369725440 |
|---|---|
| author | Tingting Guo Daniel H. Haft Daniel Wall |
| author_facet | Tingting Guo Daniel H. Haft Daniel Wall |
| author_sort | Tingting Guo |
| collection | DOAJ |
| description | ABSTRACT Cell surface proteins determine how cells interact with their biotic and abiotic environments. In social myxobacteria, a C-terminal protein sorting tag called MYXO-CTERM is universally found within the Myxococcota phylum, where their genomes typically contain dozens of proteins with this motif. MYXO-CTERM harbors a tripartite architecture: a short signature motif containing an invariant cysteine, followed by a transmembrane helix and a short arginine-rich C-terminal region localized in the cytoplasm. In Myxococcus xanthus, MYXO-CTERM is predicted to be posttranslationally lipidated and cleaved for subsequent cell surface localization by the type II secretion system. Here, following our bioinformatic discovery, we experimentally show that myxosortase (MrtX, MXAN_2755) is responsible for the C-terminal cleavage and cell surface anchoring of TraA, a prototypic cell surface receptor. The cleavage by MrtX depends on conserved cysteines within the MYXO-CTERM motif of TraA. M. xanthus mutants lacking myxosortase are defective in TraA-mediated outer membrane exchange and exhibit cell envelope defects. In a heterologous Escherichia coli expression system, the MYXO-CTERM motif is cleaved when MrtX is co-expressed. Therefore, MrtX represents a new family of sorting enzyme that enables cell surface localization of MYXO-CTERM proteins.IMPORTANCEThe CPBP (CaaX protease and bacteriocin processing) protease family is widespread across the three domains of life. Despite considerable research on eukaryotic homologs, prokaryotic CPBP family members remain largely unexplored. In this study, we experimentally reveal the function of a novel CPBP protease called myxosortase. Our findings show that myxosortase is responsible for the C-terminal cleavage and cell surface anchoring of substrate proteins containing MYXO-CTERM motifs in Myxococcus xanthus. MYXO-CTERM cleavage also occurred in a heterologous Escherichia coli host when myxosortase is co-expressed. This is the first report that a CPBP protease is involved in protein sorting in prokaryotes. This work provides important insights into the biogenesis and anchoring of cell surface proteins in gram-negative bacteria. |
| format | Article |
| id | doaj-art-7746112b0e9543fe833868481617465e |
| institution | OA Journals |
| issn | 2150-7511 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | American Society for Microbiology |
| record_format | Article |
| series | mBio |
| spelling | doaj-art-7746112b0e9543fe833868481617465e2025-08-20T02:16:44ZengAmerican Society for MicrobiologymBio2150-75112025-04-0116410.1128/mbio.04067-24Myxosortase: an intramembrane protease that sorts MYXO-CTERM proteins to the cell surfaceTingting Guo0Daniel H. Haft1Daniel Wall2Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USANational Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USADepartment of Molecular Biology, University of Wyoming, Laramie, Wyoming, USAABSTRACT Cell surface proteins determine how cells interact with their biotic and abiotic environments. In social myxobacteria, a C-terminal protein sorting tag called MYXO-CTERM is universally found within the Myxococcota phylum, where their genomes typically contain dozens of proteins with this motif. MYXO-CTERM harbors a tripartite architecture: a short signature motif containing an invariant cysteine, followed by a transmembrane helix and a short arginine-rich C-terminal region localized in the cytoplasm. In Myxococcus xanthus, MYXO-CTERM is predicted to be posttranslationally lipidated and cleaved for subsequent cell surface localization by the type II secretion system. Here, following our bioinformatic discovery, we experimentally show that myxosortase (MrtX, MXAN_2755) is responsible for the C-terminal cleavage and cell surface anchoring of TraA, a prototypic cell surface receptor. The cleavage by MrtX depends on conserved cysteines within the MYXO-CTERM motif of TraA. M. xanthus mutants lacking myxosortase are defective in TraA-mediated outer membrane exchange and exhibit cell envelope defects. In a heterologous Escherichia coli expression system, the MYXO-CTERM motif is cleaved when MrtX is co-expressed. Therefore, MrtX represents a new family of sorting enzyme that enables cell surface localization of MYXO-CTERM proteins.IMPORTANCEThe CPBP (CaaX protease and bacteriocin processing) protease family is widespread across the three domains of life. Despite considerable research on eukaryotic homologs, prokaryotic CPBP family members remain largely unexplored. In this study, we experimentally reveal the function of a novel CPBP protease called myxosortase. Our findings show that myxosortase is responsible for the C-terminal cleavage and cell surface anchoring of substrate proteins containing MYXO-CTERM motifs in Myxococcus xanthus. MYXO-CTERM cleavage also occurred in a heterologous Escherichia coli host when myxosortase is co-expressed. This is the first report that a CPBP protease is involved in protein sorting in prokaryotes. This work provides important insights into the biogenesis and anchoring of cell surface proteins in gram-negative bacteria.https://journals.asm.org/doi/10.1128/mbio.04067-24Myxococcus xanthusmyxosortasecell surface proteinouter membrane exchangeprotein sortingsortase |
| spellingShingle | Tingting Guo Daniel H. Haft Daniel Wall Myxosortase: an intramembrane protease that sorts MYXO-CTERM proteins to the cell surface mBio Myxococcus xanthus myxosortase cell surface protein outer membrane exchange protein sorting sortase |
| title | Myxosortase: an intramembrane protease that sorts MYXO-CTERM proteins to the cell surface |
| title_full | Myxosortase: an intramembrane protease that sorts MYXO-CTERM proteins to the cell surface |
| title_fullStr | Myxosortase: an intramembrane protease that sorts MYXO-CTERM proteins to the cell surface |
| title_full_unstemmed | Myxosortase: an intramembrane protease that sorts MYXO-CTERM proteins to the cell surface |
| title_short | Myxosortase: an intramembrane protease that sorts MYXO-CTERM proteins to the cell surface |
| title_sort | myxosortase an intramembrane protease that sorts myxo cterm proteins to the cell surface |
| topic | Myxococcus xanthus myxosortase cell surface protein outer membrane exchange protein sorting sortase |
| url | https://journals.asm.org/doi/10.1128/mbio.04067-24 |
| work_keys_str_mv | AT tingtingguo myxosortaseanintramembraneproteasethatsortsmyxoctermproteinstothecellsurface AT danielhhaft myxosortaseanintramembraneproteasethatsortsmyxoctermproteinstothecellsurface AT danielwall myxosortaseanintramembraneproteasethatsortsmyxoctermproteinstothecellsurface |