# Defining the attachment of collagen-like protein BclA to B. anthracis spores

> **NIH NIH R03** · UNIVERSITY OF ALABAMA AT BIRMINGHAM · 2020 · $74,250

## Abstract

PROJECT SUMMARY
 Bacteria interact with their environments primarily through proteins attached to their surfaces. These
proteins enable different lifestyles—and in the case of pathogens, direct the course of infection. The diverse
mechanisms responsible for attaching surface proteins have been investigated extensively and are frequently
used as targets in therapeutic intervention. A number of pathogenic bacteria produce infectious spores that
display a variety of important surface proteins; however, little is known about how these proteins are attached.
A prime example is the collagen-like protein BclA, which is attached to the surface of spores of Bacillus
anthracis, the causative agent of anthrax.
 The outmost exosporium layer of B. anthracis spores is composed of an external hair-like nap and an
underlying basal layer. The filaments of the nap are formed by trimers of BclA, which are tightly attached to
basal layer protein BxpB. BclA attachment occurs through its 38-residue amino terminal domain (NTD), which
is proteolytically processed during sporulation to remove residues 1-19. This event apparently triggers BclA
attachment (through residues 20-38) to BxpB to form complexes that are resistant to conditions that routinely
disrupt noncovalent interactions. The protease responsible for BclA processing has not been identified, but it
does not appear to be BxpB or an enzymatically active domain of BclA. Recombinant versions of BclA and
BxpB can form extremely tight complexes in vitro, suggesting that other factors are not required for attachment.
 The goal of this study is to define the stable interaction between BclA and BxpB. This bond is likely to
be covalent. To identify this bond, BclA-BxpB complexes will be proteolytically digested, and the resulting
peptides will be separated and sequenced by liquid chromatography-tandem mass spectrometry. The results
will identify covalently linked residues and the chemical nature of the covalent bond. Additionally, BclA and
BxpB binding sites will be mapped by using hydrogen deuterium exchange by mass spectrometry. The nature
of these sites can suggest a mechanism for covalent bond formation and, in the event that a covalent bond is
not involved, will identify noncovalent interactions capable of forming an unusually tight protein complex.
 The expected outcome of this study is the elucidation of an important and new type of protein
attachment to a bacterial cell, a spore in this case. This mechanism is likely shared by many spore-forming
bacteria that attach collagen-like proteins to their spores, including pathogens such as Clostridium difficile. It is
also possible that non-spore-forming organisms use a mechanism analogous to that of BclA-BxpB attachment
to form stable protein complexes. Furthermore, BclA and BclA homologs play important roles in pathogenesis
and persistent attachment to environmental surfaces. Thus, understanding the mechanism of BclA attachment
affords new targets for treatment and p...

## Key facts

- **NIH application ID:** 9931143
- **Project number:** 5R03AI146151-02
- **Recipient organization:** UNIVERSITY OF ALABAMA AT BIRMINGHAM
- **Principal Investigator:** CHARLES LEE TURNBOUGH
- **Activity code:** R03 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $74,250
- **Award type:** 5
- **Project period:** 2019-05-21 → 2023-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9931143

## Citation

> US National Institutes of Health, RePORTER application 9931143, Defining the attachment of collagen-like protein BclA to B. anthracis spores (5R03AI146151-02). Retrieved via AI Analytics 2026-06-14 from https://api.ai-analytics.org/grant/nih/9931143. Licensed CC0.

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