Novel Flp pilus biogenesis-dependent natural transformation

Area of Science:

• Microbiology
• Bacterial genetics
• Molecular biology

Background:

• Natural transformation is a key mechanism for genetic exchange in bacteria, but its regulation and structural components are poorly understood beyond model organisms.
• Competence development in Actinobacteria, despite the phylum's significance, remains largely uncharacterized.
• Tight adherence (tad) genes are typically associated with biofilm formation, adherence, and virulence.

Purpose of the Study:

• To investigate the role of tad genes in natural transformation in the actinobacterial species Micrococcus luteus.
• To identify the structural components and regulatory mechanisms of competence development in M. luteus.
• To determine if tad genes are involved in pilus biogenesis for genetic transformation.

Main Methods:

• Generation and analysis of individual knockout mutants for predicted tad gene clusters and a prepilin processing peptidase in M. luteus.
• Identification of the major prepilin subunit.
• Visualization of cellular structures using immunofluorescence microscopy with a tagged prepilin subunit.

Main Results:

• Tad-like genes in M. luteus are essential for genetic transformation.
• The two tad gene clusters identified contribute complementarily to the formation of a functional competence pilus.
• Filamentous structures extending from the cell surface were visualized, indicating pilus formation.

Conclusions:

• Tad genes play a novel role in natural transformation by contributing to competence pilus biogenesis in Actinobacteria.
• The findings suggest that tad genes may be broadly involved in natural transformation across the Actinobacteria phylum.
• This research expands the understanding of genetic exchange mechanisms in medically and biotechnologically relevant bacteria.