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Inorganic polyphosphate (poly-P) is a linear polymer of orthophosphate residues that serves as an energy source as well as a mediator of key cellular functions in bacteria. Recent studies have identified the metabolism of poly-P as an important mechanism that contributes to adaptation, resistance to stress and cellular homeostasis in Campylobacter jejuni , a well-established foodborne bacterial pathogen. However, the mechanisms through which poly-P and cognate enzymes impact C. jejuni as well as the metabolic pathways involved in maintaining this polymer remain largely uncharacterized. Here, we discuss potential impacts of poly-P metabolism and its relationship to other features that contribute to the pathobiology of C. jejuni. This might facilitate a better understanding of the biology of C. jejuni , which lacks many of the classical stress responses and virulence elements associated with enteric pathogens.
C. jejuni: the conundrums of a fastidious pathogen
C. jejuni , a Gram-negative, microaerophilic bacterium, is a leading cause of human foodborne gastroenteritis [1]. Although C. jejuni infections are mostly self-limiting, the pathogen has also been implicated in life-threatening neurological complications such as the Guillian-Barrésyndrome [2]. C. jejuni occurs as a commensal in a variety of food-animals, and the majority of cognate infections are linked to consumption of contaminated poultry and related products [3]. Additionally, the occurrence of C. jejuni in parahost niches, such as water, is well established. Therefore, contamination with C. jejuni poses significant economic and environmental problems [3]. Yet, measures for controlling the transmission of this pathogen have had little success owing in part to the intriguing and not-fully understood pathobiology and stress response mechanisms that define C. jejuni. For example, C. jejuni is regarded as fastidious, restricted by its microaerophilic growth requirements. Furthermore, C. jejuni lacks classical stress response mechanisms and virulence factors such as a type III secretion system and an RNA polymerase sσ S factor-mediated global stress response mechanism. So, how can C. jejuni adapt and persist in a variety of niches that represent different growth challenges? While the answer to this question is multifactorial, it necessitates a closer look at relatively unexplored systems that contribute to the biology of this important pathogen. Of particular interest is the metabolism of the poly-P molecule, which has been recently investigated in C. jejuni (see below), and...