TY - JOUR
T1 - Actin-based movement of listeria monocytogenes
T2 - Actin assembly results from the local maintenance of uncapped filament barbed ends at the bacterium surface
AU - Marchand, Jean Baptiste
AU - Moreau, Patrice
AU - Paoletti, Anne
AU - Cossart, Pascale
AU - Carlier, Marie France
AU - Pantaloni, Dominique
PY - 1995/1/1
Y1 - 1995/1/1
N2 - The thermodynamic basis for actin-based motility of Listeria monocytogenes has been investigated using cytoplasmic extracts of Xenopus eggs, initially developed by Theriot et al. (Theriot, J. A., J. Rosenblatt, D. A. Portnoy, P. J. Goldschmidt-Clermont, and T. J. Mitchison. 1994. Cell. 76:505-517) as an in vitro cell-free system. A large proportion (75%) of actin was found unpolymerized in the extracts. The amount of unassembled actin (12 μM) is accounted for by the sequestering functions of Tβ4/(Xen) (20 μM) and profilin (5 μM), the barbed ends being capped. Movement of Listeria was not abolished by depletion of over 99% of the endogenous profilin. The proline- rich sequences of ActA are unlikely to be the target of profilin. All data support the view that actin assembly at the rear of Listeria results from a local shift in steady state due to a factor, keeping filaments uncapped, bound to the surface of the bacterium, while barbed ends are capped in the bulk cytoplasm. Movement is controlled by the energetic difference (i.e., the difference in critical concentration) between the two ends of the filaments, hence a constant ATP supply and the presence of barbed end capped F-actin in the medium are required to buffer free G-actin at a high concentration. The role of membrane components is demonstrated by the facts that: (a) Listeria movement can be reconstituted in the resuspended pellets of high speed- centrifuged extracts that are enriched in membranes; (b) Actin-based motility of endogenous vesicles, exhibiting the same rocketing movement as Listeria, can be observed in the extracts.
AB - The thermodynamic basis for actin-based motility of Listeria monocytogenes has been investigated using cytoplasmic extracts of Xenopus eggs, initially developed by Theriot et al. (Theriot, J. A., J. Rosenblatt, D. A. Portnoy, P. J. Goldschmidt-Clermont, and T. J. Mitchison. 1994. Cell. 76:505-517) as an in vitro cell-free system. A large proportion (75%) of actin was found unpolymerized in the extracts. The amount of unassembled actin (12 μM) is accounted for by the sequestering functions of Tβ4/(Xen) (20 μM) and profilin (5 μM), the barbed ends being capped. Movement of Listeria was not abolished by depletion of over 99% of the endogenous profilin. The proline- rich sequences of ActA are unlikely to be the target of profilin. All data support the view that actin assembly at the rear of Listeria results from a local shift in steady state due to a factor, keeping filaments uncapped, bound to the surface of the bacterium, while barbed ends are capped in the bulk cytoplasm. Movement is controlled by the energetic difference (i.e., the difference in critical concentration) between the two ends of the filaments, hence a constant ATP supply and the presence of barbed end capped F-actin in the medium are required to buffer free G-actin at a high concentration. The role of membrane components is demonstrated by the facts that: (a) Listeria movement can be reconstituted in the resuspended pellets of high speed- centrifuged extracts that are enriched in membranes; (b) Actin-based motility of endogenous vesicles, exhibiting the same rocketing movement as Listeria, can be observed in the extracts.
UR - http://www.scopus.com/inward/record.url?scp=0028981496&partnerID=8YFLogxK
U2 - 10.1083/jcb.130.2.331
DO - 10.1083/jcb.130.2.331
M3 - Article
C2 - 7615635
AN - SCOPUS:0028981496
SN - 0021-9525
VL - 130
SP - 331
EP - 343
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 2
ER -