|SHI, XIANGYANG - University Of California|
Submitted to: Journal of Visualized Experiments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2015
Publication Date: 4/8/2016
Citation: Shi, X., Lin, H. 2016. Visualization of twitching motility and characterization of the role of the PilG in Xylella fastidiosa. Journal of Visualized Experiments. 110:e53816. doi: 10.3791/53816.
Interpretive Summary: Xylella fastidiosa (Xf) is a bacterium that causes Pierce's disease (PD) of grape. Twitching motility is essential for virulence of Xf. To reveal the role of the gene responsible for twitching motility, a time-lapse image recording system was employed to compare twitching motility between wild type and a pilG-defect mutant of Xf. The results demonstrated that PilG mutant strain exhibited no movement compared with wild type Xf. This study demonstrates that the microscopy image recording system is a useful tool for examining twitching motility.
Technical Abstract: Xylella fastidiosa is a Gram-negative non-flagellated bacterium that causes a number of economically important diseases of plants. Twitching motility provides X. fastidiosa a means for long-distance intra-plant movement and colonization, contributing toward pathogenicity of X. fastidiosa. Twitching motility of X. fastidiosa is facilitated by type IV pili. Type IV pili of Xylella fastidiosa are regulated by pilG, a chemotaxis regulator in Pil-Chp operon encoding proteins that are involved with signal transduction pathways. To elucidate the roles of pilG in twitching motility of X. fastidiosa, a pilG-deficient mutant Xf'pilG and its complementary strain Xf'pilG-C were developed. A microfluidic chamber integrated with a time-lapse image recording system was used to observe twitching motility in Xf'pilG, Xf'pilG-C and the wild type strain. Using this recording system, long-term spatial and temporal observations of aggregation and migration of individual cells and populations of bacteria via twitching motility may be observed. X. fastidiosa wild type and complementary Xf'pilG-C strain showed typical twitching motility directly observed in the microfluidic flow chamber, whereas mutant Xf'pilG exhibited a twitching deficient phenotype. This study demonstrates that pilG contributes to twitching motility of X. fastidiosa.