Structural Homology Modeling of MV2-Eury DsrAB
The structural homology model of the MV2-Eury DsrABC sequences (Figure 1E, F), was based on the hetero-hexameric structure from D. vulgaris (32) due the poor quality of the electron density for the DsrAB structure from A. fulgidus . An obvious difference between the MV2-Eury model and the template is that the β-hairpin of the DsrB subunit of MV2-Eury that contacts DsrC (Figure 1E) is much shorter than in D. vulgaris , whereas the pseudo-symmetric β-hairpin structure in the MV2-Eury DsrA subunit near the inactive siroheme (Figure 1E, bottom, green & pink) is much longer. Examination of the sequences and differences between the MV2-Eury Dsr model and the A .fulgidus heterotetramer or the D. vulgaris hetero-hexamer structures suggested that much of the sequence variation among these three homolog types was found at subunit interfaces (Figure S1).