A variant Tc4 transposable element in the nematode C. elegans could encode a novel protein

Area of Science:

• Genetics
• Molecular Biology
• Transposable Elements

Background:

• Previous analysis identified a 1605 bp Tc4 element in C. elegans lacking significant open reading frames.
• Transposable elements are mobile genetic sequences that can alter genome structure and gene expression.

Purpose of the Study:

• To characterize a novel variant of the Tc4 transposable element, designated Tc4v.
• To investigate the expression and genomic association of the Tc4v element.

Main Methods:

• DNA sequencing of the Tc4-rh1030 element.
• Sequence analysis of cDNA clones.
• Northern blot analysis.
• Analysis of transcripts from a gene with a Tc4v insertional mutation.

Main Results:

• A 3483 bp Tc4 variant (Tc4-rh1030) was sequenced, containing a 2343 bp novel sequence within an inverted repeat.
• The Tc4v element is present approximately five times per haploid genome and is associated with Tc4 elements.
• Sequence analysis suggests Tc4v contains at least five exons potentially encoding a 537 amino acid protein.
• A 1.6-kb Tc4v-specific transcript was detected in the mutator strain TR679 but not in the wild-type N2 strain.
• Tc4v sequences were frequently spliced out of mutant unc-33 transcripts.

Conclusions:

• Tc4v represents a distinct subfamily of Tc4 elements with unique sequence features.
• Tc4v is transcribed in a mutator strain where Tc4 elements are active, suggesting its involvement in transposition.
• Alternative splicing mechanisms can remove Tc4v sequences from host gene transcripts.