Preliminary model indicating aspects of the control of sulfur assimilation in A. ferrooxidans. Metabolic compounds are identified in turquoise boxes. Candidate genes and their putative protein products are coded with the same color. Genes and products suggested to be involved in nitrogen fixation and hydrogen oxidation are displayed in the red and yellow boxes respectively (not all genes have been shown for the sake of clarity). Proposed positive (+) and negative (-) regulatory pathways are shown with dotted lines.