modC is part of a set of genes, modABC, which encode the bacterial molybdate ABC transporter. ModC comprises the ATPase. Of the three structural Mod proteins, ModC has received the least attention, believed to be little different from ATPases of other ABC complexes. However, findings of multiple copies of modC in A. vinelandii and identification of a potential molybdate-binding domain in the C-terminal of ModC may point to a more complex role. ORF10 is one of three copies of modC in A. vinelandii; atypically, ORF10 is not found with genes encoding the other ABC transporter components but is instead found as part of the nif gene cluster, encoding molybdenum nitrogenase. The role of ORF10 is investigated here via sequence analysis and comparison of growth of a ORF10- A. vinelandii strain with wild type growth. Findings imply ORF10 optimizes growth under conditions requiring nitrogenixation, specifically under those conditions where molybdate-availability is limited.