The enzyme that starts the synthesis of fatty acids, acetyl-CoA carboxylase or ACCase, is highly regulated and relevant to the oil content of oilseed crops. With Jay Thelen’s lab, we are uncovering in part how its subunits called BADCs slow down ACCase activity in chloroplasts. (This is supported by NSF MCB 1716688).

Bacterial phosphohexomutases move a phosphoryl group across a 6-carbon sugar, in the course of making carbohydrates at cell surfaces, such as virulence factors. We reported the mobility of domain 4 and mixed phosphorylation of a 52 kDa bacterial PGM/PMM, together with collaborator Lesa Beamer (Sarma et al., 2012). Phosphorylation of the active site closes the cleft a little while phosphosugar binding closes it fully. Both phosphorylation and binding have almost globally stabilizing effects on the enzyme (Xu et al., 2015, Biophys. J.; Xu et al., 2017, Sci. Rep.). (This was supported by NSF MCB-1409898).

Publications cited:

Sarma AV, Anbanandam A, Kelm A, Mehra-Chaudhary R, Wei Y, Qin P, Lee Y, Berjanskii MV, Mick JA, Beamer LJ, Van Doren SR. Solution NMR of a 463-residue phosphohexomutase: domain 4 mobility, substates, and phosphoryl transfer defect. Biochemistry. 2012 Jan 24;51(3):807-19. https://doi.org/10.1021/bi201609n

Xu J, Lee Y, Beamer LJ, Van Doren SR. Phosphorylation in the catalytic cleft stabilizes and attracts domains of a phosphohexomutase. Biophys J. 2015 Jan 20;108(2):325-37. https://doi.org/10.1016/j.bpj.2014.12.003

Xu J, Sarma AVS, Wei Y, Beamer LJ, Van Doren SR. Multiple Ligand-Bound States of a Phosphohexomutase Revealed by Principal Component Analysis of NMR Peak Shifts. Sci Rep. 2017 Jul 13;7(1):5343. https://doi.org/10.1038/s41598-017-05557-w