|Gungabissoon, R. A., Khan,
S., Hussey, P. J. & Maciver, S. K. (2001) Interaction of EF1a
from Zea mays (ZmEF1a) with F-actin
and interplay with the maize actin severing protein, ZmADF3., Cell
Motility Cytoskeleton. 49, 104-111.
|EF-1alpha is an abundant eukaryotic
protein whose principle function appears to be to bind aminoacyl-tRNA to
the ribosome. However, it is also known that EF-1alpha from other
sources binds both microtubules and microfilaments. We report the
expression of Zea mays EF-1alpha (ZmEF-1alpha) in bacteria and that this
protein has similar actin-binding properties as other EF-1alpha members.
ZmEF-1alpha bundles actin filaments at low pH (6.5) and inhibits the
addition of monomer at both filament ends, possibly as a consequence.
ZmEF-1alpha binds actin filaments at all pH values tested (pH 6.0-8.0),
indicating that one actin binding site is not pH sensitive. One of the
actin-binding sites was determined to reside within domain I (1-223) of
ZmEF-1alpha, but this domain did not affect the kinetics of
polymerisation. We show that the bundling activity of ZmEF-1alpha is
modulated by ZmADF3 a (a Zea mays ADF/cofilin), an actin filament
severing protein, in vitro. Bundling of actin filaments caused by
ZmEF-1alpha was enhanced in the presence of ZmADF3. The pH-dependent
activities of both proteins in vitro suggests that they may work
together to respond to temporal and spatial intracellular pH changes to
regulate the pattern of the growth of plant cells.