Dehydrogenase; part of the gene cluster that mediates the biosynthesis of the mycotoxin citrinin, a hepato-nephrotoxic compound to humans due to inhibition of respiration complex III (PubMed:27913218, PubMed:19012408, PubMed:19111642, PubMed:28238725). The pathway begins with the synthesis of a keto-aldehyde intermediate by the citrinin PKS (pksCT) from successive condensations of 4 malonyl-CoA units, presumably with a simple acetyl-CoA starter unit (PubMed:28238725). Release of the keto-aldehyde intermediate is consistent with the presence of the C-terminal reductive release domain (PubMed:28238725). Mp11 collaborates with pksCT by catalyzing the hydrolysis of ACP-bound acyl intermediates to free the ACP from stalled intermediates (By similarity). Mpl2 then catalyzes the oxidation of the C-12 methyl of the ketone intermediate to an alcohol intermediate which is further oxidized by the oxidoreductase mpl7 to produce a bisaldehyde intermediate (PubMed:27913218). The fourth catalytic step is catalyzed by the mpl4 aldehyde dehydrogenase (PubMed:27913218). The final transformation is the reduction of C-3 by mpl6 to provide the chemically stable citrinin nucleus (PubMed:27913218). Mycotoxin biosynthesis. Homodimer. Belongs to the GMC oxidoreductase family.