scholarly journals GAP45 Phosphorylation Controls Assembly of the Toxoplasma Myosin XIV Complex

2008 ◽  
Vol 8 (2) ◽  
pp. 190-196 ◽  
Author(s):  
Stacey D. Gilk ◽  
Elizabeth Gaskins ◽  
Gary E. Ward ◽  
Con J. M. Beckers
Keyword(s):  
Myosin Light Chain ◽  
Integral Membrane Protein ◽  
Soluble Complex ◽  
Inner Membrane ◽  
Motor Complex ◽  
Membrane Complex ◽  
Final Assembly ◽  
Parasite Survival ◽  
Inner Membrane Complex

ABSTRACT Toxoplasma gondii motility is powered by the myosin XIV motor complex, which consists of the myosin XIV heavy chain (MyoA), the myosin light chain (MLC1), GAP45, and GAP50, the membrane anchor of the complex. MyoA, MLC1, and GAP45 are initially assembled into a soluble complex, which then associates with GAP50, an integral membrane protein of the parasite inner membrane complex. While all proteins in the myosin XIV motor complex are essential for parasite survival, the specific role of GAP45 remains unclear. We demonstrate here that final assembly of the motor complex is controlled by phosphorylation of GAP45. This protein is phosphorylated on multiple residues, and by using mass spectroscopy, we have identified two of these, Ser163 and Ser167. The importance of these phosphorylation events was determined by mutation of Ser163 and Ser167 to Glu and Ala residues to mimic phosphorylated and nonphosphorylated residues, respectively. Mutation of Ser163 and Ser167 to either Ala or Glu residues does not affect targeting of GAP45 to the inner membrane complex or its association with MyoA and MLC1. Mutation of Ser163 and Ser167 to Ala residues also does not affect assembly of the mutant GAP45 protein into the myosin motor complex. Mutation of Ser163 and Ser167 to Glu residues, however, prevents association of the MyoA-MLC1-GAP45 complex with GAP50. These observations indicate that phosphorylation of Ser163 and Ser167 in GAP45 controls the final step in assembly of the myosin XIV motor complex.

scholarly journals Identification of the membrane receptor of a class XIV myosin in Toxoplasma gondii

2004 ◽  
Vol 165 (3) ◽  
pp. 383-393 ◽  
Author(s):  
Elizabeth Gaskins ◽  
Stacey Gilk ◽  
Nicolette DeVore ◽  
Tara Mann ◽  
Gary Ward ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Protein Complex ◽  
Integral Membrane Protein ◽  
Gliding Motility ◽  
Host Cells ◽  
Inner Membrane ◽  
Apicomplexan Parasites ◽  
Membrane Complex ◽  
Inner Membrane Complex ◽  
Two Stages

Apicomplexan parasites exhibit a unique form of substrate-dependent motility, gliding motility, which is essential during their invasion of host cells and during their spread between host cells. This process is dependent on actin filaments and myosin that are both located between the plasma membrane and two underlying membranes of the inner membrane complex. We have identified a protein complex in the apicomplexan parasite Toxoplasma gondii that contains the class XIV myosin required for gliding motility, TgMyoA, its associated light chain, TgMLC1, and two novel proteins, TgGAP45 and TgGAP50. We have localized this complex to the inner membrane complex of Toxoplasma, where it is anchored in the membrane by TgGAP50, an integral membrane glycoprotein. Assembly of the protein complex is spatially controlled and occurs in two stages. These results provide the first molecular description of an integral membrane protein as a specific receptor for a myosin motor, and further our understanding of the motile apparatus underlying gliding motility in apicomplexan parasites.

scholarly journals The Role of Palmitoylation for Protein Recruitment to the Inner Membrane Complex of the Malaria Parasite

2014 ◽  
Vol 290 (3) ◽  
pp. 1712-1728 ◽  
Author(s):  
Johanna Wetzel ◽  
Susann Herrmann ◽  
Lakshmipuram Seshadri Swapna ◽  
Dhaneswar Prusty ◽  
Arun T. John Peter ◽  
...  
Keyword(s):  
Malaria Parasite ◽  
Inner Membrane ◽  
Membrane Complex ◽  
Inner Membrane Complex ◽  
Protein Recruitment

scholarly journals Immobilization of the Type XIV Myosin Complex in Toxoplasma gondii

2007 ◽  
Vol 18 (8) ◽  
pp. 3039-3046 ◽  
Author(s):  
Terezina M. Johnson ◽  
Zenon Rajfur ◽  
Ken Jacobson ◽  
Con J. Beckers
Keyword(s):  
Toxoplasma Gondii ◽  
Large Fraction ◽  
Complex Surface ◽  
Membrane Domains ◽  
Inner Membrane ◽  
Apicomplexan Parasites ◽  
Motor Complex ◽  
Membrane Complex ◽  
Inner Membrane Complex ◽  
Cytoskeletal Elements

The substrate-dependent movement of apicomplexan parasites such as Toxoplasma gondii and Plasmodium sp. is driven by the interaction of a type XIV myosin with F-actin. A complex containing the myosin-A heavy chain, a myosin light chain, and the accessory protein GAP45 is attached to the membranes of the inner membrane complex (IMC) through its tight interaction with the integral membrane glycoprotein GAP50. For the interaction of this complex with F-actin to result in net parasite movement, it is necessary that the myosin be immobilized with respect to the parasite and the actin with respect to the substrate the parasite is moving on. We report here that the myosin motor complex of Toxoplasma is firmly immobilized in the plane of the IMC. This does not seem to be accomplished by direct interactions with cytoskeletal elements. Immobilization of the motor complex, however, does seem to require cholesterol. Both the motor complex and the cholesterol are found in detergent-resistant membrane domains that encompass a large fraction of the inner membrane complex surface. The observation that the myosin XIV motor complex of Toxoplasma is immobilized within this cholesterol-rich membrane likely extends to closely related pathogens such as Plasmodium and possibly to other eukaryotes.

scholarly journals Identification and Molecular Dissection of IMC32, a Conserved Toxoplasma Inner Membrane Complex Protein That Is Essential for Parasite Replication

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Juan A. Torres ◽  
Rebecca R. Pasquarelli ◽  
Peter S. Back ◽  
Andy S. Moon ◽  
Peter J. Bradley
Keyword(s):  
Toxoplasma Gondii ◽  
Coiled Coil ◽  
Inner Membrane ◽  
Content Type ◽  
Apicomplexan Parasites ◽  
Conserved Regions ◽  
Membrane Complex ◽  
Parasite Survival ◽  
Parasite Replication ◽  
Inner Membrane Complex

ABSTRACT The inner membrane complex (IMC) is a unique organelle of apicomplexan parasites that plays critical roles in parasite motility, host cell invasion, and replication. Despite the common functions of the organelle, relatively few IMC proteins are conserved across the phylum and the precise roles of many IMC components remain to be characterized. Here, we identify a novel component of the Toxoplasma gondii IMC (IMC32) that localizes to the body portion of the IMC and is recruited to developing daughter buds early during endodyogeny. IMC32 is essential for parasite survival, as its conditional depletion results in a complete collapse of the IMC that is lethal to the parasite. We demonstrate that localization of IMC32 is dependent on both an N-terminal palmitoylation site and a series of C-terminal coiled-coil domains. Using deletion analyses and functional complementation, we show that two conserved regions within the C-terminal coiled-coil domains play critical roles in protein function during replication. Together, this work reveals an essential component of parasite replication that provides a novel target for therapeutic intervention of T. gondii and related apicomplexan parasites. IMPORTANCE The IMC is an important organelle that apicomplexan parasites use to maintain their intracellular lifestyle. While many IMC proteins have been identified, only a few central players that are essential for internal budding have been described and even fewer are conserved across the phylum. Here, we identify IMC32, a novel component of the Toxoplasma gondii IMC that localizes to very early daughter buds, indicating a role in the early stages of parasite replication. We then demonstrate that IMC32 is essential for parasite survival and pinpoint conserved regions within the protein that are important for membrane association and daughter cell formation. As IMC32 is unique to these parasites and not present in their mammalian hosts, it serves as a new target for the development of drugs that exclusively affect these important intracellular pathogens.

scholarly journals Raft microdomain localized in the luminal leaflet of inner membrane complex of living Toxoplasma gondii

2021 ◽  
Vol 100 (2) ◽  
pp. 151149
Author(s):  
Rikako Konishi ◽  
Yuna Kurokawa ◽  
Kanna Tomioku ◽  
Tatsunori Masatani ◽  
Xuenan Xuan ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Inner Membrane ◽  
Membrane Complex ◽  
Inner Membrane Complex

scholarly journals Metamorphoses of malaria: the role of autophagy in parasite differentiation

2011 ◽  
Vol 51 ◽  
pp. 127-136 ◽  
Author(s):  
Isabelle Coppens
Keyword(s):  
Life Cycle ◽  
Complex Life Cycle ◽  
Mammalian Host ◽  
Protozoan Parasites ◽  
Membrane Complex ◽  
Autophagic Process ◽  
Inner Membrane Complex ◽  
Form Development ◽  
High Degree

Several protozoan parasites undergo a complex life cycle that alternates between an invertebrate vector and a vertebrate host. Adaptations to these different environments by the parasites are achieved by drastic changes in their morphology and metabolism. The malaria parasites must be transmitted to a mammal from a mosquito as part of their life cycle. Upon entering the mammalian host, extracellular malaria sporozoites reach the liver and invade hepatocytes, wherein they meet the challenge of becoming replication-competent schizonts. During the process of conversion, the sporozoite selectively discards organelles that are unnecessary for the parasite growth in liver cells. Among the organelles that are cleared from the sporozoite are the micronemes, abundant secretory vesicles that facilitate the adhesion of the parasite to hepatocytes. Organelles specialized in sporozoite motility and structure, such as the inner membrane complex (a major component of the motile parasite's cytoskeleton), are also eliminated from converting parasites. The high degree of sophistication of the metamorphosis that occurs at the onset of the liver-form development cascade suggests that the observed changes must be multifactorial. Among the mechanisms implicated in the elimination of sporozoite organelles, the degradative process called autophagy contributes to the remodelling of the parasite interior and the production of replicative liver forms. In a broader context, the importance of the role played by autophagy during the differentiation of protozoan parasites that cycle between insects and vertebrates is nowadays clearly emerging. An exciting prospect derived from these observations is that the parasite proteins involved in the autophagic process may represent new targets for drug development.

scholarly journals Gliding Associated Proteins Play Essential Roles during the Formation of the Inner Membrane Complex of Toxoplasma gondii

2016 ◽  
Vol 12 (2) ◽  
pp. e1005403 ◽  
Author(s):  
Clare R. Harding ◽  
Saskia Egarter ◽  
Matthew Gow ◽  
Elena Jiménez-Ruiz ◽  
David J. P. Ferguson ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Inner Membrane ◽  
Membrane Complex ◽  
Associated Proteins ◽  
Inner Membrane Complex
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