UNIGE document Scientific Article
previous document  unige:20375  next document
add to browser collection
Title

Toxoplasma gondii profilin acts primarily to sequester G-actin while formins efficiently nucleate actin filament formation in vitro

Authors
Skillman, Kristen M
Ma, Christopher I
Sibley, L David
Published in Biochemistry. 2012, vol. 51, no. 12, p. 2486-95
Abstract Apicomplexan parasites employ gliding motility that depends on the polymerization of parasite actin filaments for host cell entry. Despite this requirement, parasite actin remains almost entirely unpolymerized at steady state; formation of filaments required for motility relies on a small repertoire of actin-binding proteins. Previous studies have shown that apicomplexan formins and profilin exhibit canonical functions on heterologous actins from higher eukaryotes; however, their biochemical properties on parasite actins are unknown. We therefore analyzed the impact of T. gondii profilin (TgPRF) and FH1-FH2 domains of two formin isoforms in T. gondii (TgFRM1 and TgFRM2) on the polymerization of T. gondii actin (TgACTI). Our findings based on in vitro assays demonstrate that TgFRM1-FH1-FH2 and TgFRM2-FH1-FH2 dramatically enhanced TgACTI polymerization in the absence of profilin, making them the sole protein factors known to initiate polymerization of this normally unstable actin. In addition, T. gondii formin domains were shown to both initiate polymerization and induce bundling of TgACTI filaments; however, they did not rely on TgPRF for these activities. In contrast, TgPRF sequestered TgACTI monomers, thus inhibiting polymerization even in the presence of formins. Collectively, these findings provide insight into the unusual control mechanisms of actin dynamics within the parasite.
Identifiers
PMID: 22397711
Full text
Article (Author postprint) (1.6 MB) - public document Free access
Structures
Research group Biologie d'un parasite intracellulaire obligatoire (773)
Citation
(ISO format)
SKILLMAN, Kristen M et al. Toxoplasma gondii profilin acts primarily to sequester G-actin while formins efficiently nucleate actin filament formation in vitro. In: Biochemistry, 2012, vol. 51, n° 12, p. 2486-95. https://archive-ouverte.unige.ch/unige:20375

202 hits

862 downloads

Update

Deposited on : 2012-05-15

Export document
Format :
Citation style :