Animal septins contain functional transmembrane domains.

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Septins are essential filament-forming proteins involved in cell division, polarity, and membrane trafficking.
• The precise mechanisms by which septins associate with cellular membranes remain incompletely understood.

Purpose of the Study:

• To identify and characterize novel mechanisms of septin-membrane association.
• To investigate the function of a predicted transmembrane domain (TMD)-containing septin isoform.

Main Methods:

• Bioinformatic analysis to identify TMD-containing septins across phylogeny.
• Functional characterization of a Caenorhabditis elegans septin UNC-61 TMD isoform.
• Assays to determine the necessity of TMD function for tissue integrity.
• Demonstration of membrane localization using a primate TMD-septin sequence.

Main Results:

• An isoform of C. elegans septin UNC-61 containing a predicted transmembrane domain (TMD) was identified.
• This TMD isoform is expressed in specific tissues and is required for the integrity of the egg-laying apparatus.
• TMD-containing septins are conserved across opisthokont phylogeny.
• A primate TMD-septin sequence is sufficient for localization to cellular membranes.

Conclusions:

• A novel mechanism of septin-membrane association via a transmembrane domain has been revealed.
• This finding provides new insights into the dynamics and regulation of septin proteins.
• The discovery has significant implications for understanding septin function in various cellular processes.