Electron microscopy reveals cristae remodeling within mitochondria of
GAS-infected cells. A, mitochondria in control cells treated with
media display typical ultrastructure with the inner membrane projecting into
the matrix at crista junctions to form lamellar cristae. B,
mitochondria in GAS-infected cells show altered cristae structure consistent
with swollen crista compartments. C, some mitochondria in GAS-treated
cells have a different appearance with irregularly shaped cristae
cross-sections within a very dense matrix compartment. D, Q-VD-OPH
effectively prevents the alterations of mitochondrial structure found in
GAS-infected macrophages. Several mitochondria, including the one at lower
right, maintain normal crista structure despite being immediately
adjacent to a phagocytosed GAS cell slightly left of center in this
image. E, cells treated with purified SLO showing mitochondria with
dilated cristae similar to those treated with GAS in B. F,
mitochondria in SLO-treated cells with condensed matrix compartments similar
to those following GAS treatment in C. Scale bar indicates 200
nm.