期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：24
页码：7563-7568
DOI：10.1073/pnas.1502025112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceIn their natural environments, bacteria frequently transition from a free-swimming state to a surface-associated state, attached to a substratum. As they encounter a surface, they may initiate developmental programs to optimally colonize this new environment and induce pathways such as virulence. Here we demonstrate that the pathogen Pseudomonas aeruginosa uses fiber-like motorized appendages called type IV pili to sense initial contact with surfaces. This leads to a signaling cascade that results in the expression of hundreds of genes associated with pathogenicity and surface-specific twitching motility. Thus, bacteria use pili not only to attach and move, but also to sense mechanical features of their environment and regulate cellular processes of surface-associated lifestyles. Bacteria have evolved a wide range of sensing systems to appropriately respond to environmental signals. Here we demonstrate that the opportunistic pathogen Pseudomonas aeruginosa detects contact with surfaces on short timescales using the mechanical activity of its type IV pili, a major surface adhesin. This signal transduction mechanism requires attachment of type IV pili to a solid surface, followed by pilus retraction and signal transduction through the Chp chemosensory system, a chemotaxis-like sensory system that regulates cAMP production and transcription of hundreds of genes, including key virulence factors. Like other chemotaxis pathways, pili-mediated surface sensing results in a transient response amplified by a positive feedback that increases type IV pili activity, thereby promoting long-term surface attachment that can stimulate additional virulence and biofilm-inducing pathways. The methyl-accepting chemotaxis protein-like chemosensor PilJ directly interacts with the major pilin subunit PilA. Our results thus support a mechanochemical model where a chemosensory system measures the mechanically induced conformational changes in stretched type IV pili. These findings demonstrate that P. aeruginosa not only uses type IV pili for surface-specific twitching motility, but also as a sensor regulating surface-induced gene expression and pathogenicity.
关键词：surface sensing ; mechanotransduction ; type IV pili ; virulence
