Fig. 7: A model for PlsMtb and PlsB2tb substrates recognition.

a Surface representation of the predicted PlsMtb 3D structure, showing the palmitoyl moiety of C16:0-CoA deeply buried into a hydrophobic groove. This hydrophobic pocket runs perpendicular with respect to a main groove where the CoA moiety is located. The 4-phosphopantetheinate moiety of C16:0-CoA is placed in the hydrophobic groove entrance, nearby the catalytic site, with the adenosine 3´,5´-ADP moiety extended along the protein surface. The G3P acceptor substrate is positioned in the opposite site of the CoA group, in a binding pocket mainly decorated by polar residues. b The palmitoyl moiety of C16:0-CoA makes interactions with W2, H41, S47, F48, P51, L52, F60, F80, Y81, S84, Q86 along the groove’s walls and with F6, K7 and Y3 in the bottom, supporting PlsMtb’s specificity for C16-length donor substrates. The 4-phosphopantetheinate moiety of C16:0-CoA is placed nearby the catalytic residues H41 and D46 and stabilized by Y117 with the adenosine 3´,5´-ADP moiety making interactions with residues R91, T121, R137, T133, R194, Y216 and K132. The G3P is stabilized by the R122, Y66 and N77 residues. c Surface representation of the predicted PlsB2tb 3D structure, showing the stearoyl moiety of C18:0-CoA deeply buried into a hydrophobic tunnel of the acyltransferase domain. This hydrophobic tunnel runs perpendicular with respect to a main groove where the CoA moiety is located. The 4-phosphopantetheinate moiety of C18:0-CoA is placed in the hydrophobic groove entrance, nearby the catalytic site, with the adenosine 3´,5´-ADP moiety extended along the protein surface. The G3P acceptor substrate is positioned in the opposite site of the CoA group, in a binding pocket mainly decorated by polar residues. d The stearoyl moiety of C18:0-CoA makes interactions with E290, M289, V233, P286, S317, M314, M319, M299, V236, V283 and Y279 along the groove’s walls. The 4-phosphopantetheinate moiety of C18:0-CoA is placed nearby the catalytic residues H276 and D281 and further stabilized by L305, N304 and I322, with the adenosine 3´,5´-ADP moiety making interactions with residues N325, I326, K368, N328, K333, R466 and R324. G3P is stabilized by the R358, R360 and T357 residues.