Figure 4

Quaternary Structure of PyrD. A) PyrD 1A from Lactococcus lactis is a homodimer (1JUB colored cyan). B) PyrD from L. lactis 1B is a heterotetramer. The homodimer interface at the center of PyrD 1B (1EP3 colored blue) is similar to the interface in PyrD 1A. PyrD 1B has an additional subunit PyrK (colored red). This implies that PyrD 1B is derived from PyrD 1A.