Step-Wise Loss of Bacterial Flagellar Torsion Confers Progressive Phagocytic Evasion

PLoS Pathogens

Julie L. Acker¹  Rustin R. Lovewell¹  Brent Berwin¹  Ryan M. Collins¹  George A. O'Toole¹  Matthew J. Wargo² 

[1] Department of Microbiology and Immunology, Dartmouth Medical School, Lebanon, New Hampshire, United States of America;Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, Vermont, United States of America

关键词: Phagocytosis;    Pseudomonas aeruginosa;    Phagocytes;    Swimming;    Flagellar motility;    Macrophages;    Vibrio cholerae;    Pathogen motility;   

DOI  :  10.1371/journal.ppat.1002253

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Phagocytosis of bacteria by innate immune cells is a primary method of bacterial clearance during infection. However, the mechanisms by which the host cell recognizes bacteria and consequentially initiates phagocytosis are largely unclear. Previous studies of the bacterium Pseudomonas aeruginosa have indicated that bacterial flagella and flagellar motility play an important role in colonization of the host and, importantly, that loss of flagellar motility enables phagocytic evasion. Here we use molecular, cellular, and genetic methods to provide the first formal evidence that phagocytic cells recognize bacterial motility rather than flagella and initiate phagocytosis in response to this motility. We demonstrate that deletion of genes coding for the flagellar stator complex, which results in non-swimming bacteria that retain an initial flagellar structure, confers resistance to phagocytic binding and ingestion in several species of the gamma proteobacterial group of Gram-negative bacteria, indicative of a shared strategy for phagocytic evasion. Furthermore, we show for the first time that susceptibility to phagocytosis in swimming bacteria is proportional to mot gene function and, consequently, flagellar rotation since complementary genetically- and biochemically-modulated incremental decreases in flagellar motility result in corresponding and proportional phagocytic evasion. These findings identify that phagocytic cells respond to flagellar movement, which represents a novel mechanism for non-opsonized phagocytic recognition of pathogenic bacteria.

【 授权许可】

CC BY