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Expression analysis of the Theileria parva subtelomere-encoded variable secreted protein gene family.

Schmuckli-Maurer J, Casanova C, Schmied S, Affentranger S, Parvanova I, Kang'a S, Nene V, Katzer F, McKeever D, Müller J, Bishop R, Pain A, Dobbelaere DA - PLoS ONE (2009)

Bottom Line: The pattern of mRNA expression was largely defined by the parasite genotype and not by host background or cell type, and found to be relatively stable in vitro over a period of two months.Epitope-tagged TP03_0882 expressed in mammalian cells was found to translocate into the nucleus, a process that could be attributed to two different nuclear localisation signals.Whereas in cell lines established from a cloned parasite transcripts can be found corresponding to a wide range of SVSP genes, only a minority of parasites appear to express a particular SVSP protein.

View Article: PubMed Central - PubMed

Affiliation: Molecular Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.

ABSTRACT

Background: The intracellular protozoan parasite Theileria parva transforms bovine lymphocytes inducing uncontrolled proliferation. Proteins released from the parasite are assumed to contribute to phenotypic changes of the host cell and parasite persistence. With 85 members, genes encoding subtelomeric variable secreted proteins (SVSPs) form the largest gene family in T. parva. The majority of SVSPs contain predicted signal peptides, suggesting secretion into the host cell cytoplasm.

Methodology/principal findings: We analysed SVSP expression in T. parva-transformed cell lines established in vitro by infection of T or B lymphocytes with cloned T. parva parasites. Microarray and quantitative real-time PCR analysis revealed mRNA expression for a wide range of SVSP genes. The pattern of mRNA expression was largely defined by the parasite genotype and not by host background or cell type, and found to be relatively stable in vitro over a period of two months. Interestingly, immunofluorescence analysis carried out on cell lines established from a cloned parasite showed that expression of a single SVSP encoded by TP03_0882 is limited to only a small percentage of parasites. Epitope-tagged TP03_0882 expressed in mammalian cells was found to translocate into the nucleus, a process that could be attributed to two different nuclear localisation signals.

Conclusions: Our analysis reveals a complex pattern of Theileria SVSP mRNA expression, which depends on the parasite genotype. Whereas in cell lines established from a cloned parasite transcripts can be found corresponding to a wide range of SVSP genes, only a minority of parasites appear to express a particular SVSP protein. The fact that a number of SVSPs contain functional nuclear localisation signals suggests that proteins released from the parasite could contribute to phenotypic changes of the host cell. This initial characterisation will facilitate future studies on the regulation of SVSP gene expression and the potential biological role of these enigmatic proteins.

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Schematic presentation of TP08_0882, a typical SVSP.A. Schematic view and amino acid sequence of TP03_0882. TP03_0882 is 607 amino acids long. The polypeptide has a putative signal peptide (SP) for secretion (purple) with a cleavage site after residue 21 (predicted by the SignalP3.0 web server). A large N-terminal region containing abundant Q and P residues (red) is followed by C-terminal region containing two nuclear localisation signals (NLS 1 and 2, blue) and two FAINT domains from aa 422 to 481 and aa 520 to 579 (green). B. Analysis of the TP03_0882 protein using the FoldIndex© software. The N-terminal region of the protein is intrinsically unfolded, while the conserve C-terminal region is predicted to fold.
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pone-0004839-g001: Schematic presentation of TP08_0882, a typical SVSP.A. Schematic view and amino acid sequence of TP03_0882. TP03_0882 is 607 amino acids long. The polypeptide has a putative signal peptide (SP) for secretion (purple) with a cleavage site after residue 21 (predicted by the SignalP3.0 web server). A large N-terminal region containing abundant Q and P residues (red) is followed by C-terminal region containing two nuclear localisation signals (NLS 1 and 2, blue) and two FAINT domains from aa 422 to 481 and aa 520 to 579 (green). B. Analysis of the TP03_0882 protein using the FoldIndex© software. The N-terminal region of the protein is intrinsically unfolded, while the conserve C-terminal region is predicted to fold.

Mentions: The amino acid sequence of a SVSP (TP03_0882) containing the characteristic features of this family is presented in Figure 1A. The general structure of SVSPs consists of a short conserved N-terminal region, in most cases containing a putative signal peptide for secretion, followed by a QP-rich region which is predicted to be highly unstructured (Fig. 1B) [27]. The conserved C-terminus has no significant identity to known proteins and nearly all SVSP molecules contain Theileria-specific, highly divergent domains termed ‘frequently associated in Theileria’ (FAINT). The function of these domains that contain approximately 70 amino acid residues is currently unknown [25].


Expression analysis of the Theileria parva subtelomere-encoded variable secreted protein gene family.

Schmuckli-Maurer J, Casanova C, Schmied S, Affentranger S, Parvanova I, Kang'a S, Nene V, Katzer F, McKeever D, Müller J, Bishop R, Pain A, Dobbelaere DA - PLoS ONE (2009)

Schematic presentation of TP08_0882, a typical SVSP.A. Schematic view and amino acid sequence of TP03_0882. TP03_0882 is 607 amino acids long. The polypeptide has a putative signal peptide (SP) for secretion (purple) with a cleavage site after residue 21 (predicted by the SignalP3.0 web server). A large N-terminal region containing abundant Q and P residues (red) is followed by C-terminal region containing two nuclear localisation signals (NLS 1 and 2, blue) and two FAINT domains from aa 422 to 481 and aa 520 to 579 (green). B. Analysis of the TP03_0882 protein using the FoldIndex© software. The N-terminal region of the protein is intrinsically unfolded, while the conserve C-terminal region is predicted to fold.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2657828&req=5

pone-0004839-g001: Schematic presentation of TP08_0882, a typical SVSP.A. Schematic view and amino acid sequence of TP03_0882. TP03_0882 is 607 amino acids long. The polypeptide has a putative signal peptide (SP) for secretion (purple) with a cleavage site after residue 21 (predicted by the SignalP3.0 web server). A large N-terminal region containing abundant Q and P residues (red) is followed by C-terminal region containing two nuclear localisation signals (NLS 1 and 2, blue) and two FAINT domains from aa 422 to 481 and aa 520 to 579 (green). B. Analysis of the TP03_0882 protein using the FoldIndex© software. The N-terminal region of the protein is intrinsically unfolded, while the conserve C-terminal region is predicted to fold.
Mentions: The amino acid sequence of a SVSP (TP03_0882) containing the characteristic features of this family is presented in Figure 1A. The general structure of SVSPs consists of a short conserved N-terminal region, in most cases containing a putative signal peptide for secretion, followed by a QP-rich region which is predicted to be highly unstructured (Fig. 1B) [27]. The conserved C-terminus has no significant identity to known proteins and nearly all SVSP molecules contain Theileria-specific, highly divergent domains termed ‘frequently associated in Theileria’ (FAINT). The function of these domains that contain approximately 70 amino acid residues is currently unknown [25].

Bottom Line: The pattern of mRNA expression was largely defined by the parasite genotype and not by host background or cell type, and found to be relatively stable in vitro over a period of two months.Epitope-tagged TP03_0882 expressed in mammalian cells was found to translocate into the nucleus, a process that could be attributed to two different nuclear localisation signals.Whereas in cell lines established from a cloned parasite transcripts can be found corresponding to a wide range of SVSP genes, only a minority of parasites appear to express a particular SVSP protein.

View Article: PubMed Central - PubMed

Affiliation: Molecular Pathobiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.

ABSTRACT

Background: The intracellular protozoan parasite Theileria parva transforms bovine lymphocytes inducing uncontrolled proliferation. Proteins released from the parasite are assumed to contribute to phenotypic changes of the host cell and parasite persistence. With 85 members, genes encoding subtelomeric variable secreted proteins (SVSPs) form the largest gene family in T. parva. The majority of SVSPs contain predicted signal peptides, suggesting secretion into the host cell cytoplasm.

Methodology/principal findings: We analysed SVSP expression in T. parva-transformed cell lines established in vitro by infection of T or B lymphocytes with cloned T. parva parasites. Microarray and quantitative real-time PCR analysis revealed mRNA expression for a wide range of SVSP genes. The pattern of mRNA expression was largely defined by the parasite genotype and not by host background or cell type, and found to be relatively stable in vitro over a period of two months. Interestingly, immunofluorescence analysis carried out on cell lines established from a cloned parasite showed that expression of a single SVSP encoded by TP03_0882 is limited to only a small percentage of parasites. Epitope-tagged TP03_0882 expressed in mammalian cells was found to translocate into the nucleus, a process that could be attributed to two different nuclear localisation signals.

Conclusions: Our analysis reveals a complex pattern of Theileria SVSP mRNA expression, which depends on the parasite genotype. Whereas in cell lines established from a cloned parasite transcripts can be found corresponding to a wide range of SVSP genes, only a minority of parasites appear to express a particular SVSP protein. The fact that a number of SVSPs contain functional nuclear localisation signals suggests that proteins released from the parasite could contribute to phenotypic changes of the host cell. This initial characterisation will facilitate future studies on the regulation of SVSP gene expression and the potential biological role of these enigmatic proteins.

Show MeSH
Related in: MedlinePlus