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ORIGINAL RESEARCH ARTICLE

Identification and characterization of novel outer membrane proteins of Brachyspira pilosicoli

Amisha Panda1 ,  Jahnvi Kapoor1 ,  Batchu Hareramadas2 ,  Ilmas Naqvi2 ,  Ravindresh Chhabra3 ,  Sanjiv Kumar4* ,  Anannya Bandyopadhyay1*
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1 Department of Zoology, Faculty of Science, University of Delhi, New Delhi, Delhi, India
2 Department of Zoology, Zakir Husain Delhi College, University of Delhi, New Delhi, Delhi, India
3 Department of Biochemistry, School of Basic Sciences, Central University of Punjab, Bathinda, Punjab, India
4 Independent Researcher, Stockholm, Sweden
MI, 025230050 https://doi.org/10.36922/MI025230050
Received: 6 June 2025 | Revised: 9 July 2025 | Accepted: 1 August 2025 | Published online: 25 August 2025
© 2025 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
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Abstract

Brachyspira pilosicoli is a globally prevalent, anaerobic, Gram-negative spirochete that causes intestinal spirochetosis in birds, pigs, and humans. It colonizes the large intestine, causing colitis, diarrhea, and impaired growth. Despite its pathogenic relevance, the outer membrane proteins of B. pilosicoli remain largely uncharacterized. In this study, we computationally identified a total of 42 outer membrane β-barrel (OMBB) proteins within the B. pilosicoli proteome using a consensus-based computational framework. Structural models generated using AlphaFold 3 confirmed the β-barrel architectures of the predicted proteins. Structure- and sequence-based functional annotations revealed homologs of b-barrel assembly machinery BamA protein, lipopolysaccharide-assembly protein LPS-assembly protein D, TolC, transporter proteins, enzymes, diffusion channels, and porins. Notably, seven of the predicted OMBB proteins were previously unannotated in UniProt and the National Center for Biotechnology Information; we report their putative functions here for the 1st time. Sequence variation analysis among the homologs of OMBB proteins across nine B. pilosicoli strains revealed that many of the variations were present within surface-exposed loop regions, suggesting roles in host interaction and immune modulation. Our in silico study expands the functional repertoire of B. pilosicoli outer membrane proteins, highlighting potential targets for diagnostics, vaccine development, and therapeutic interventions.

Graphical abstract
Keywords
Brachyspira pilosicoli
Intestinal spirochetosis
Outer membrane proteins
β-barrel structures
Structural models
Sequence variations
Functional annotations
In silico
Funding
Amisha Panda is a recipient of a junior research fellowship from the Department of Biotechnology, Government of India (grant number: DBT/2023-24/UOD/2326). Jahnvi Kapoor is a recipient of a junior research fellowship from the University Grants Commission, Government of India (grant number: 231620067077).
Conflict of interest
The authors declare that they have no competing interests.
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