Elongasome core proteins and class A PBP1a display zonal, processive movement at the midcell of Streptococcus pneumoniae .

exhibits zonal, circumferential motion. This motion is independent of FtsZ treadmilling or the presence of MreB filaments and is separate from the circumferential motion of the septal PG synthase that closes the septal annulus. Also unlike in rod-shaped bacteria, a Class A PBP moves processively at midcell, distinctly from components of the core PG elongasome or septal PG synthase. Thus, processive, circumferential motion in pneumococcal cells follows spatially separate linear tracks that may reflect a common ordered structure in the existing peptidoglycan itself. In contrast, the MpgA muramidase displays a different kind of subdiffusive motion that is largely confined to midcell by an unknown mechanism.