The inverted repeats of Tn5 are functionally different.

Area of Science:

• Molecular Biology
• Genetics
• Microbiology

Background:

• Transposons, like Tn5, are mobile genetic elements with significant roles in genome evolution.
• Tn5 contains inverted repeats that flank its internal sequences.
• The functional and structural properties of these inverted repeats are crucial for transposition.

Purpose of the Study:

• To investigate the differential functional properties of the two inverted repeats of Tn5.
• To elucidate the specific roles of each repeat in RNA polymerase binding, neomycin resistance, polypeptide coding, and transposition.

Main Methods:

• Analysis of restriction endonuclease cleavage patterns.
• Assessment of RNA polymerase binding affinities.
• Evaluation of neomycin resistance promotion.
• Identification and characterization of polypeptides encoded by the repeats.
• Functional assays for transposition activity.

Main Results:

• Identical restriction endonuclease cleavage patterns for both inverted repeats.
• Differential RNA polymerase binding, with a weak site in one repeat linked to neomycin resistance.
• Each inverted repeat encodes two polypeptides of different molecular weights.
• Polypeptides from only one inverted repeat are essential for Tn5 transposition.

Conclusions:

• The inverted repeats of Tn5, despite sequence similarity, possess distinct functional attributes.
• These functional differences are critical for Tn5's biological activity, including transposition and gene expression.
• Understanding these distinctions provides insight into the regulatory mechanisms of transposition.