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A malaria membrane skeletal protein is essential for normal morphogenesis, motility, and infectivity of sporozoites.

Khater EI, Sinden RE, Dessens JT - J. Cell Biol. (2004)

Bottom Line: Knockout of PbIMC1a protein expression reduces, but does not abolish, sporozoite gliding locomotion.We identify a family of proteins related to PbIMC1a in Plasmodium and other apicomplexan parasites.These results provide new functional insight in the role of membrane skeletons in apicomplexan parasite biology.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Imperail College London, London SW7 2AZ, England, UK.

ABSTRACT
Membrane skeletons are structural elements that provide mechanical support to the plasma membrane and define cell shape. Here, we identify and characterize a putative protein component of the membrane skeleton of the malaria parasite. The protein, named PbIMC1a, is the structural orthologue of the Toxoplasma gondii inner membrane complex protein 1 (TgIMC1), a component of the membrane skeleton in tachyzoites. Using targeted gene disruption in the rodent malaria species Plasmodium berghei, we show that PbIMC1a is involved in sporozoite development, is necessary for providing normal sporozoite cell shape and mechanical stability, and is essential for sporozoite infectivity in insect and vertebrate hosts. Knockout of PbIMC1a protein expression reduces, but does not abolish, sporozoite gliding locomotion. We identify a family of proteins related to PbIMC1a in Plasmodium and other apicomplexan parasites. These results provide new functional insight in the role of membrane skeletons in apicomplexan parasite biology.

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Sequence and structure of PbIMC1a. (A) Diagram of the intron/exon structure of the PbIMC1a gene. Introns are indicated with v-shaped lines with sizes in nucleotides. (B) ClustalW multiple alignment of PbIMC1a (Pb), PyIMC1a (Py), PfIMC1a (Pf), PvIMC1a (Pv), and TgIMC1 (Tg). Indicated are conserved domains (shaded); terminal cysteine motifs (bold and in italics); gaps introduced to allow optimal alignment (hyphens). Conserved amino acid identities (asterisks) and similarities (colons and points) are shown underneath. (C) Schematic diagram of the protein structure of TgIMC1 and its structural homologues in Plasmodium spp. The proteins shown are based on predicted proteins of P. yoelii, GenBank/EMBL/DDBJ accession nos. EAA16469 (PyIMC1a), EAA15257 (PyIMC1b), EAA16185 (PyIMC1c), EAA17029 (PyIMC1d), EAA15249 (PyIMC1e), EAA15609 (PyIMC1f), EAA15402 (PyIMC1g), and EAA20426 (PyIMC1h). Boxes mark domains corresponding to the conserved amino-terminal domain (hatched), central domain (gray), and carboxy-terminal domain (open). Conserved terminal cysteine motifs are indicated with open circles.
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fig1: Sequence and structure of PbIMC1a. (A) Diagram of the intron/exon structure of the PbIMC1a gene. Introns are indicated with v-shaped lines with sizes in nucleotides. (B) ClustalW multiple alignment of PbIMC1a (Pb), PyIMC1a (Py), PfIMC1a (Pf), PvIMC1a (Pv), and TgIMC1 (Tg). Indicated are conserved domains (shaded); terminal cysteine motifs (bold and in italics); gaps introduced to allow optimal alignment (hyphens). Conserved amino acid identities (asterisks) and similarities (colons and points) are shown underneath. (C) Schematic diagram of the protein structure of TgIMC1 and its structural homologues in Plasmodium spp. The proteins shown are based on predicted proteins of P. yoelii, GenBank/EMBL/DDBJ accession nos. EAA16469 (PyIMC1a), EAA15257 (PyIMC1b), EAA16185 (PyIMC1c), EAA17029 (PyIMC1d), EAA15249 (PyIMC1e), EAA15609 (PyIMC1f), EAA15402 (PyIMC1g), and EAA20426 (PyIMC1h). Boxes mark domains corresponding to the conserved amino-terminal domain (hatched), central domain (gray), and carboxy-terminal domain (open). Conserved terminal cysteine motifs are indicated with open circles.

Mentions: We used BLAST homology searches with the TgIMC1 amino acid sequence to identify orthologous genes in Plasmodium. The highest sequence homology (33% amino acid identity) was found with a predicted protein of Plasmodium yoelii. We designed primers to this gene to PCR amplify the cognate gene in P. berghei. Sequence analysis of two distinct PCR products amplified from genomic and cDNA, respectively, allowed us to map four introns in the P. berghei gene, named PbIMC1a (Fig. 1 A). The sequence data have been submitted to the GenBank database under accession no. AF542052. The orthologous genes in P. yoelii (PyIMC1a), P. falciparum (PfIMC1a) and Plasmodium vivax (PvIMC1a) are also predicted to contain four introns each at similar positions to those found experimentally in PbIMC1a.


A malaria membrane skeletal protein is essential for normal morphogenesis, motility, and infectivity of sporozoites.

Khater EI, Sinden RE, Dessens JT - J. Cell Biol. (2004)

Sequence and structure of PbIMC1a. (A) Diagram of the intron/exon structure of the PbIMC1a gene. Introns are indicated with v-shaped lines with sizes in nucleotides. (B) ClustalW multiple alignment of PbIMC1a (Pb), PyIMC1a (Py), PfIMC1a (Pf), PvIMC1a (Pv), and TgIMC1 (Tg). Indicated are conserved domains (shaded); terminal cysteine motifs (bold and in italics); gaps introduced to allow optimal alignment (hyphens). Conserved amino acid identities (asterisks) and similarities (colons and points) are shown underneath. (C) Schematic diagram of the protein structure of TgIMC1 and its structural homologues in Plasmodium spp. The proteins shown are based on predicted proteins of P. yoelii, GenBank/EMBL/DDBJ accession nos. EAA16469 (PyIMC1a), EAA15257 (PyIMC1b), EAA16185 (PyIMC1c), EAA17029 (PyIMC1d), EAA15249 (PyIMC1e), EAA15609 (PyIMC1f), EAA15402 (PyIMC1g), and EAA20426 (PyIMC1h). Boxes mark domains corresponding to the conserved amino-terminal domain (hatched), central domain (gray), and carboxy-terminal domain (open). Conserved terminal cysteine motifs are indicated with open circles.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2172497&req=5

fig1: Sequence and structure of PbIMC1a. (A) Diagram of the intron/exon structure of the PbIMC1a gene. Introns are indicated with v-shaped lines with sizes in nucleotides. (B) ClustalW multiple alignment of PbIMC1a (Pb), PyIMC1a (Py), PfIMC1a (Pf), PvIMC1a (Pv), and TgIMC1 (Tg). Indicated are conserved domains (shaded); terminal cysteine motifs (bold and in italics); gaps introduced to allow optimal alignment (hyphens). Conserved amino acid identities (asterisks) and similarities (colons and points) are shown underneath. (C) Schematic diagram of the protein structure of TgIMC1 and its structural homologues in Plasmodium spp. The proteins shown are based on predicted proteins of P. yoelii, GenBank/EMBL/DDBJ accession nos. EAA16469 (PyIMC1a), EAA15257 (PyIMC1b), EAA16185 (PyIMC1c), EAA17029 (PyIMC1d), EAA15249 (PyIMC1e), EAA15609 (PyIMC1f), EAA15402 (PyIMC1g), and EAA20426 (PyIMC1h). Boxes mark domains corresponding to the conserved amino-terminal domain (hatched), central domain (gray), and carboxy-terminal domain (open). Conserved terminal cysteine motifs are indicated with open circles.
Mentions: We used BLAST homology searches with the TgIMC1 amino acid sequence to identify orthologous genes in Plasmodium. The highest sequence homology (33% amino acid identity) was found with a predicted protein of Plasmodium yoelii. We designed primers to this gene to PCR amplify the cognate gene in P. berghei. Sequence analysis of two distinct PCR products amplified from genomic and cDNA, respectively, allowed us to map four introns in the P. berghei gene, named PbIMC1a (Fig. 1 A). The sequence data have been submitted to the GenBank database under accession no. AF542052. The orthologous genes in P. yoelii (PyIMC1a), P. falciparum (PfIMC1a) and Plasmodium vivax (PvIMC1a) are also predicted to contain four introns each at similar positions to those found experimentally in PbIMC1a.

Bottom Line: Knockout of PbIMC1a protein expression reduces, but does not abolish, sporozoite gliding locomotion.We identify a family of proteins related to PbIMC1a in Plasmodium and other apicomplexan parasites.These results provide new functional insight in the role of membrane skeletons in apicomplexan parasite biology.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Imperail College London, London SW7 2AZ, England, UK.

ABSTRACT
Membrane skeletons are structural elements that provide mechanical support to the plasma membrane and define cell shape. Here, we identify and characterize a putative protein component of the membrane skeleton of the malaria parasite. The protein, named PbIMC1a, is the structural orthologue of the Toxoplasma gondii inner membrane complex protein 1 (TgIMC1), a component of the membrane skeleton in tachyzoites. Using targeted gene disruption in the rodent malaria species Plasmodium berghei, we show that PbIMC1a is involved in sporozoite development, is necessary for providing normal sporozoite cell shape and mechanical stability, and is essential for sporozoite infectivity in insect and vertebrate hosts. Knockout of PbIMC1a protein expression reduces, but does not abolish, sporozoite gliding locomotion. We identify a family of proteins related to PbIMC1a in Plasmodium and other apicomplexan parasites. These results provide new functional insight in the role of membrane skeletons in apicomplexan parasite biology.

Show MeSH
Related in: MedlinePlus