Alternative splicing: a novel mechanism of regulation identified in the chorismate mutase gene of the potato cyst nematode Globodera rostochiensis.

Abstract

Chorismate mutase (CM) secreted from the stylet of plant-parasitic nematodes plays an important role in plant parasitism. We isolated and characterized a new nematode CM gene (Gr-cm-1) from the potato cyst nematode, Globodera rostochiensis. The Gr-cm-1 gene was found to exist in the nematode genome as a single-copy gene that has two different alleles, Gr-cm-1A and Gr-cm-1B, both of which could give rise to two different mRNA transcripts of Gr-cm-1 and Gr-cm-1-IRII. In situ mRNA hybridization showed that the Gr-cm-1 gene was exclusively expressed within the subventral oesophageal gland cells of the nematode. Gr-cm-1 was demonstrated to encode a functional CM (GR-CM-1) potentially having a dimeric structure as the secreted bacterial *AroQ CMs. Gr-cm-1-IRII, generated by retention of intron 2 of the Gr-cm-1 pre-mRNA through alternative splicing (AS), would encode a truncated protein (GR-CM-1t) lacking the CM domain with no CM activity. The quantitative real-time reverse transcription-PCR assay revealed that splicing of the Gr-cm-1 gene was developmentally regulated; Gr-cm-1 was up-regulated whereas Gr-cm-1-IRII was down-regulated in early nematode parasitic stages compared to the preparasitic juvenile stage. Low-temperature SDS-PAGE analysis revealed that GR-CM-1 could form homodimers when expressed in Escherichia coli and the dimerization domain was retained in the truncated GR-CM-1t protein. The specific interaction between the two proteins was demonstrated in yeast. Our data suggested that the novel splice variant might function as a dominant negative isoform through heterodimerization with the full-length GR-CM-1 protein and that AS may represent an important mechanism for regulating CM activity during nematode parasitism.

• Authors: Shun-Wen Lu, Duanhua Tian, Harmony B Borchardt-Wier, Xiaohong Wang
• Journal: Molecular and biochemical parasitology (Mol Biochem Parasitol) Vol. 162 Issue 1 Pg. 1-15 (Nov 2008) ISSN: 0166-6851 [Print] Netherlands
• PMID: 18786575 (Publication Type: Journal Article)

Chemical References

• Protein Isoforms
• Chorismate Mutase

Topics

• Alternative Splicing
• Amino Acid Sequence
• Animals
• Base Sequence
• Chorismate Mutase (genetics, metabolism)
• Dimerization
• Escherichia coli (enzymology, genetics)
• Gene Expression Regulation, Developmental
• Host-Parasite Interactions
• Introns (genetics)
• Molecular Sequence Data
• Plant Diseases (parasitology)
• Protein Isoforms
• Sequence Analysis, DNA
• Solanum tuberosum (parasitology)
• Two-Hybrid System Techniques
• Tylenchoidea (enzymology, genetics, metabolism, physiology)