The Bacillus subtilis cell division proteins FtsL and DivIC are intrinsically unstable and do not interact with one another in the absence of other septasomal components.
The bacterial septum appears to comprise a macromolecular assembly of essential cell division proteins (the 'septasome') that are responsible for physically dividing the cell during cytokinesis. FtsL and DivIC are essential components of this division machinery in Bacillus subtilis. We used yeast two-hybrid analysis as well as a variety of biochemical and biophysical methods to examine the proposed interaction between Bacillus subtilis FtsL and DivIC. We show that FtsL and DivIC are thermodynamically unstable proteins that are likely to be unfolded and therefore targeted for degradation unless stabilized by interactions with other components of the septasome. However, we show that this stabilization does not result from a direct interaction between FtsL and DivIC. We propose that the observed interdependence of DivIC and FtsL stability is a result of indirect interactions that are mediated by other septasomal proteins.
Robson
Scott A
SA
Department of Biochemistry, University of Connecticut Health Center, Farmington 06032, USA.
Michie
Katharine A
KA
Mackay
Joel P
JP
Harry
Elizabeth
E
King
Glenn F
GF
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000166:cytology / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism*; D002455:Cell Division; D002942:Circular Dichroism; D029968:Escherichia coli Proteins; D007526:Isoelectric Point; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009391:Nephelometry and Turbidimetry; D019906:Nuclear Magnetic Resonance, Biomolecular; D011489:Protein Denaturation; D017510:Protein Folding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013816:Thermodynamics; D020798:Two-Hybrid System Techniques; D014461:Ultracentrifugation
D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; C110609:DivIC protein, Bacillus subtilis; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; C078387:ftsL protein, E coli