Non-Essentiality of \u3ci\u3ealr\u3c/i\u3e and \u3ci\u3emurI\u3c/i\u3e Genes in Mycobacteria

Amino acids are the building blocks of life. If DNA is the blueprint, amino acids are the lumber that proteins are built with. Proteins are built with left-handed, L- forms of amino acids. Bacteria have an essential cell wall component that happens to be an exception: peptidoglycan. Bacteria have enzymes called racemases that convert L- amino acid forms into right-handed, D- forms. Amino acids participate in many reactions with keto acids. Transaminases allow conversion between amino acids by transfer of an amino group. Previous reports claimed there is no D-ala transaminase activity in mycobacteria and thus alr and murI genes encode essential functions. However, in studies performed by our lab, alr and murI mutants were able to grow on minimal or low-nitrogen content media. This suggests there is D-ala transaminase activity in mycobacteria and thus alr and murI genes encode essential functions. We complete a carbon-source experiment that supports this hypothesis