Unveiling the Molecular Mechanism of Bacterial Cell Division

A research team led by David Reverter at the Autonomous University of Barcelona (UAB) has identified the molecular mechanism that regulates cell division in bacteria. This groundbreaking discovery details how the MraZ protein interacts with the dcw gene cluster, and the findings have been published in Nature Communications.

The Core Process: Bacterial Cell Division

Cell division is a fundamental biological process. In most bacteria, this essential function is controlled by the dcw operon, a cluster of genes responsible for producing proteins vital for both cell division and bacterial wall formation.

MraZ: The Key Regulator

The MraZ protein functions as a transcription factor. It binds to the promoter region of the dcw operon, a critical step that initiates the transcription of genes within the operon. This process ultimately leads to the production of proteins necessary for bacterial division. MraZ is uniquely positioned as the first gene in the dcw operon across various bacteria, underscoring its role as a key regulator of this vital process.

Advanced Techniques Reveal Specific Interactions

The UAB team utilized sophisticated structural biology techniques, including X-ray crystallography and cryo-electron microscopy, to observe this intricate mechanism directly. Their study specifically focused on the interaction between the MraZ factor and the dcw operon's promoter in Mycoplasma genitalium, a bacterium frequently chosen for research due to its remarkably small genome.

A Crucial Structural Change

The dcw operon's promoter is characterized by four repeated six-nucleotide 'boxes.' Cryo-electron microscopy allowed researchers to visualize the specific contacts between the MraZ factor and these promoter DNA sequences at near-atomic resolution. They made a pivotal observation: the MraZ protein, which typically forms an octamer (an eight-subunit ring), undergoes a significant structural change during binding to the DNA.

According to David Reverter, the MraZ protein's donut-shaped octamer structure deforms, allowing four of its subunits to bind to the four promoter boxes. This structural distortion is crucial for MraZ to regulate cell division.

Universal Implications for Bacterial Life

This direct observation of MraZ-DNA interactions represents a significant advancement in understanding bacterial cell division initiation. It moves beyond previous studies that relied solely on biochemical methods and computational modeling. The researchers conclude that this regulatory mechanism is likely universal among most bacteria due to the highly conserved nature of MraZ proteins and dcw operon promoter sequences across species.

The study involved valuable collaboration with the ALBA synchrotron and the cryo-electron microscopy service at the Institute of Genetics and Molecular and Cellular Biology in Strasbourg, France.