4.2.1.32	down	expression of ttdA is repressed by O2 in an FNR-dependent manner. Presence of nitrate strongly represses ttdA. When glucose is present in addition to L-tartrate, expression of ttdA'-'lacZ is decreased to 24% of the L-tartrate-induced state	705573	
4.2.1.32	up	expression of plasmid-encoded ttdA'-'lacZ is stimulated to a high level (64fold) by L-tartrate during anaerobic growth. meso-Tartrate causes slightly lower (47.5fold) induction. During aerobic growth, expression of ttdA'-'lacZ is very low in the presence or absence of L-tartrate, and it increases by a factor of about 220 under anaerobic conditions. Expression of ttdA requires transcriptional activation by fumarate nitrate reductase regulator (FNR), which is in the active state only under anaerobic conditions	705573