Catalyzes the transfer of acetyl from acetyl-CoA to desacetylmycothiol (Cys-GlcN-Ins) to form mycothiol. 1D-myo-inositol 2-(L-cysteinylamino)-2-deoxy-alpha-D-glucopyranoside + acetyl-CoA = CoA + H(+) + mycothiol Optimum pH is 8.2-8.5. Monomer. The N-terminal acetyl-CoA does not function as substrate in the catalyzed reaction, but is believed to have a structural role. Was identified as a high-confidence drug target. Belongs to the acetyltransferase family. MshD subfamily.