Structural investigation of MosA
MosA is an enzyme from Sinorhizobium meliloti L5-30, a beneficial soil bacterium. Initial investigation into this enzyme categorized it as a methyltransferase. Further investigation revealed that this was incorrect, and that MosA is actually a dihydrodipicolinate synthase, part of the N-acetylneuraminate lyase superfamily. One of the characteristics of enzyme superfamilies is their low sequence identity, but relatively high structural similarity. The structural investigation reported here confirms the high structural similarity between MosA and other superfamily members. Investigation of MosA was carried out by means of x-ray crystallography. It was believed that detailed structural information may shed light into not only the enzymatic mechanism, but also the inhibition of MosA by lysine, the final product of the enzymatic pathway. Insight into enzyme mechanism and inhibition may ultimately prove useful in herbicide or insecticide development, as other dihydrodipicolinate synthases from harmful fungi, bacteria, or plants, make attractive targets for inhibition. Lysine is an essential amino acid for humans, meaning that there is no endogenous lysine production to block the use of these hypothetical inhibitors. Specific inhibitors based on crystal structures have proven to be effective in the past and hopefully, will continue to be useful in the future. Here we report the structure of MosA, solved to 1.95 Å resolution with lysine 161 forming a Schiff-base adduct with pyruvate. This adduct is consistent with the currently accepted dihydrodipicolinate synthase enzyme mechanism.
protein crystallography, Sinorhizobium meliloti L5-30, MosA, dihydrodipicolinate synthase
Master of Science (M.Sc.)