The secret life of lactate: A novel cell-cycle regulatory mechanism

The lac operon in Escherichia coli is a model for understanding inducible gene regulation and metabolic flexibility. It integrates local control by lactose and global regulation through catabolite repression, enabling E. coli to preferentially metabolize glucose when available and switch to lactose utilization when glucose is scarce.Structure and Function of the lac OperonThe lac operon contains three structural genes: lacZ (β-galactosidase), lacY (lactose permease), and lacA...

Prokaryotes can control gene expression through operons—DNA sequences consisting of regulatory elements and clustered, functionally related protein-coding genes. Operons use a single promoter sequence to initiate transcription of a gene cluster (i.e., a group of structural genes) into a single mRNA molecule. The terminator sequence ends transcription. An operator sequence, located between the promoter and structural genes, prohibits the operon’s transcriptional activity if bound by...

The cell cycle regulation directs how a cell proceeds from one phase to the next and begins mitosis. The cell cycle control system includes intracellular regulatory molecules and external triggers. They provide "stop" or "advance" signals and operate at specific cell cycle stages termed checkpoints to ensure that a particular process is completed before the cell advances to the next phase.
Cyclins and cyclin-dependent kinases (Cdks) are the primary cell cycle regulators and...

Several external and internal factors influence the initiation and inhibition of cell division. For instance, the death of nearby cells or the release of human growth hormone (hGH) promotes cell division. In contrast, lack of hGH or crowding of cells can inhibit cell division.
Several proteins function as internal regulators to ensure each cell cycle stage is completed faithfully before proceeding to the next. Regulator molecules may act directly or influence the activity or production of other...

Cell size is a significant factor impacting cellular design, function, and fitness. There exists some internal coordination by which cells double their masses before division, thus, achieving homeostasis. Coordination between cell growth and proliferation depends on the checkpoints in between cell cycle phases. Loss of coordination or failure in the checkpoint mechanism can drive the cell to uncontrolled growth and loss of cellular function. Like dividing cells that coordinate cellular growth,...

To consistently produce healthy cells, the cell cycle—the process that generates daughter cells—must be precisely regulated.