Bacterial flagella protein key to how gut immune cells distinguish between good and pathogenic bacteria
These are electron microscope pictures of near-identical looking bacterial flagella – the tiny tail-like structures that propel the microorganisms through fluids. According to recent research, all flagella are not the same, however, and the small differences that exist are critical to how the human immune system determines which bacteria are friendly and which are not. The principal component of flagella is flagellin, and recognition of this protein by gut immune cells can trigger an immune response. Since both friendly and pathogenic bacteria can have flagellin, scientists wondered how the immune cells tell them apart. Screening the flagellins of a variety of gut bacteria has revealed that while some bind and activate the immune cells, others bind and do not, and some don’t bind at all. Subtle differences in the amino acid sequence of the protein, it turns out, are enough to give some bacteria a free pass and others the boot.
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.