Jittery, a Mutator distant relative with a paradoxical mobile behavior: excision without reinsertion.

Area of Science:

• Genetics
• Molecular Biology
• Plant Science

Background:

• The maize mutation bz-m039 exhibits instability attributed to a mobile genetic element.
• This element, named Jittery (Jit), was identified in maize infected with barley stripe mosaic virus.

Purpose of the Study:

• To characterize the structure and properties of the Jittery (Jit) mobile element in maize.
• To investigate the relationship of Jit to other known mobile genetic elements, particularly Mutator-like elements (MULEs).

Main Methods:

• Sequence analysis of the Jit element and its predicted protein (JITA).
• Comparison of Jit's structural features (TIRs, target site duplication) with known transposons.
• Analysis of Jit's excision frequency and its presence in different maize lines and related species.

Main Results:

• Jit is a 3.9-kb mobile element with 181 bp terminal inverted repeats (TIRs) and causes a 9-bp direct target site duplication.
• Jit is predicted to encode a single protein (JITA), distantly related to MURA transposase but more closely related to MURA proteins of MULEs.
• Jit excises frequently, producing germinal revertants, but does not leave footprints or reinsert, thus not qualifying as a bona fide transposon in its current host.

Conclusions:

• Jit represents a unique mobile element in maize with unusual excision characteristics.
• Its properties suggest a potential evolutionary link or functional divergence from classical transposons and MULEs.
• Further research is needed to fully understand the mechanisms and implications of Jit's mobility and its impact on maize genetics.