Surface sensing stimulates cellular differentiation in Caulobacter crescentus.

Area of Science:

• Microbiology
• Cell Biology
• Biophysics

Background:

• Cellular differentiation is crucial for specialized functions.
• Caulobacter crescentus has a unique dimorphic life cycle.
• Regulation of this cycle by mechanical cues is not well understood.

Purpose of the Study:

• Investigate how environmental cues, specifically surface contact, regulate the Caulobacter crescentus cell cycle.
• Determine the role of physical inputs like pilus retraction in cell differentiation.

Main Methods:

• Utilized chemical perturbations and genetic mutations (CpaC) to obstruct pilus activity.
• Compared cell-cycle progression and chromosome replication initiation in surface-stimulated vs. planktonic cells.
• Analyzed the synthesis of cyclic diguanylate monophosphate (c-di-GMP) and histidine kinase activity.

Main Results:

• Surface sensing via pilus retraction physically accelerates cell-cycle progression and differentiation.
• Obstructing pilus activity or retraction stimulates early chromosome replication.
• Surface contact enhances cell-cycle progression similarly to obstructed pilus activity.
• Pilus retraction obstruction increases cyclic diguanylate monophosphate (c-di-GMP) synthesis via altered histidine kinase activity.

Conclusions:

• Surface contact and pilus activity alterations are key regulators of Caulobacter crescentus cell differentiation.
• Cells bypass programmed delays to adapt rapidly to surface-associated lifestyles.
• Pilus retraction is a critical mechanical signal for initiating faster cell cycles and differentiation.