Related Experiment Videos
Identification and characterization of a basic cell surface-located protein from Lactobacillus fermentum BR11
M S Turner1, P Timms, L M Hafner
1Centre for Molecular Biotechnology, School of Life Science, Queensland University of Technology, Brisbane, Australia.
Journal of Bacteriology
|May 1, 1997
Summary
Researchers identified a novel cell surface protein, BspA, from Lactobacillus fermentum BR11. This protein, crucial for bacterial function, is anchored electrostatically, offering new insights into Gram-positive bacterial cell wall interactions.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Lactobacillus fermentum BR11 is a probiotic bacterium.
- Cell surface proteins play vital roles in bacterial adhesion and function.
- Understanding protein anchoring mechanisms in Gram-positive bacteria is crucial.
Purpose of the Study:
- To identify and characterize a predominant 32 kDa polypeptide from Lactobacillus fermentum BR11.
- To elucidate the structure, function, and anchoring mechanism of this novel protein, designated BspA.
Main Methods:
- Extraction of bacterial cells using LiCl.
- Cloning and sequencing of the gene encoding the polypeptide.
- N-terminal sequencing and homology analysis.
- Biotinylation, trypsin digestion, and isoelectric point prediction.
- Selective extraction using acidic buffer.
Main Results:
- A 32 kDa polypeptide, BspA, was isolated and its gene sequenced, revealing a 28,625 Da protein.
- BspA shares sequence similarity with bacterial solute-binding proteins and is part of an operon for an ATP-binding cassette-type uptake system.
- BspA lacks a lipoprotein cleavage motif but is exposed on the cell surface.
- The positively charged BspA (pI 10.59) is anchored via electrostatic interactions with acidic cell surface groups, removable by acidic buffer extraction.
Conclusions:
- BspA is a novel cell surface protein of Lactobacillus fermentum BR11.
- Its unique anchoring mechanism in a Gram-positive bacterium provides new understanding of bacterial cell surface architecture.
- BspA's role in an uptake system suggests involvement in nutrient acquisition.