FtsBLQ

FtsBLQ refers to the three protein components FtsB, FtsL, and FtsQ, which form a subcomplex of the bacterial divisome essential for cell division in many Gram-negative bacteria, notably Escherichia coli. All three are inner membrane proteins: FtsB and FtsL are small, single-pass membrane proteins with substantial periplasmic domains that participate in a heterodimer; FtsQ is a larger periplasmic protein with a single transmembrane helix anchoring it to the inner membrane.

Function and role: The FtsBLQ complex localizes to the division site at midcell and acts as a scaffold that coordinates the assembly of late divisome proteins such as FtsW and FtsI, and the recruitment of FtsN. It is thought to regulate the timing of septal peptidoglycan synthesis, coupling the progression of divisome maturation to enzymatic activity that drives cell wall constriction.

Mechanism: Through interactions among FtsB, FtsL, and FtsQ, the complex modulates interactions with downstream partners and may relieve inhibitory constraints on cell wall synthesis. Genetic disruption of any component often results in cell division defects, filamentation, or lethality, with temperature-sensitive mutants frequently used to study function.

Localization and regulation: The complex is dynamically regulated during the cell cycle, remaining at the division septum until constriction progresses and the division machinery completes assembly.

See also: Divisome; FtsZ; FtsW; FtsI; FtsN; bacterial cytokinesis.