Caf1 capsule antigen

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Caf1 capsule antigen is a family of proteins that form the F1 capsule on the surface of Yersinia bacteria, including Yersinia pestis. The Caf1 proteins fold into a compact shape made of seven beta-strands arranged into two beta-sheets in a Greek-key topology. This capsule helps the bacterium reach and establish infection at sites of infection. Scientists have studied its structure using X-ray crystallography, confirming the seven-strand, two-sheet Greek-key fold that underpins Caf1 assembly and function.