Adapter Protein SH2-Bβ Stimulates Actin-Based Motility of
Listeria monocytogenes
in a Vasodilator-Stimulated Phosphoprotein (VASP)-Dependent Fashion
Article (Web of Science)
ABSTRACT
SH2-Bβ (Src homology 2 Bβ) is an adapter protein that is required for maximal growth hormone-dependent actin reorganization in membrane ruffling and cell motility. Here we show that SH2-Bβ is also required for maximal actin-based motility of
Listeria monocytogenes
. SH2-Bβ localizes to
Listeria
-induced actin tails and increases the rate of bacterial propulsion in infected cells and in cell extracts. Furthermore,
Listeria
motility is decreased in mouse embryo fibroblasts from SH2-B
−/−
mice. Both recruitment of SH2-Bβ to
Listeria
and SH2-Bβ stimulation of actin-based propulsion require the vasodilator-stimulated phosphoprotein (VASP), which binds ActA at the surfaces of
Listeria
cells and enhances bacterial actin-based motility. SH2-Bβ enhances actin-based movement of ActA-coated beads in a biomimetic actin-based motility assay, provided that VASP is present. In vitro binding assays show that SH2-Bβ binds ActA but not VASP; however, binding to ActA is greater in the presence of VASP. Because VASP also plays an essential regulatory role in actin-based processes in eukaryotic cells, the present results provide mechanistic insight into the functions of both SH2-Bβ and VASP in motility and also increase our understanding of the fundamental mechanism by which
Listeria
spreads.
