Salmonella cells have hijacked the protein-building process to maintain their ability to cause illness, new research suggests. Scientists say that these bacteria have modified what has long been considered typical cell behavior by using a beta form of an amino acid -- as opposed to an alpha form -- during the act of making proteins.
Beta versions of amino acids occur in nature under rare and specific circumstances, but have never been observed as part of protein synthesis. Before this finding, in fact, researchers had determined that virtually all proteins were constructed with the alpha forms of amino acids.
This work has shown that when researchers delete any one of three genes from the process that makes use of the beta form of the amino acid, or if they insert the alpha form in the beta version's place, Salmonella cells are no longer able to cause disease. The amino acid in question is lysine, one of 22 genetically encoded amino acids that are strung together in cells to make proteins.
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"The tRNA synthetase paralog PoxA modifies elongation factor-P with (R)-β-lysine." (http://www.nature.com/nchembio/journal/vaop/ncurrent/full/nchembio.632.html)