Chemotactic response of Helicobacter pylori to human plasma and bile

Abstract

To clarify further the role of chemotaxis in Helicobacter pylori colonization, the in vitro bacterium response to human plasma and bile (secretions containing chemoeffector compounds that are present in the gastric mucus layer) was examined. Human plasma, after dilution to 1 % (v/v) with buffer, was found to be a chemoattractant for the motile bacillus. Human gall-bladder bile, after dilution to 2 % (v/v) with buffer, was found to be a chemorepellent, but did not cause the motility of the bacillus to be diminished after prolonged exposure. The basis of the chemoattractant effect of plasma was explored by examining how urea and 12 amino acids found in plasma affected the taxis of H. pylori. Urea and the amino acids histidine, glutamine, glycine and arginine were the strongest chemoattractants. Other amino acids were chemoattractants, with the exceptions of aspartic and glutamic acids, which were chemorepellents. The basis of the chemorepellent effect of bile was explored by examining how the six most abundant conjugated bile acids in human bile affected the taxis of H. pylori. All the bile acids were chemorepellents, with the greatest effects being demonstrated by taurocholic and taurodeoxycholic acids. The implications of these findings for H. pylori colonization of gastric epithelium are discussed.

The Helicobacter pylori Chemotaxis Receptor TlpB (HP0103) Is Required for pH Taxis and for Colonization of the Gastric Mucosa

“…These findings do not exclude cheV2 and cheV3 in other specialized chemotactic responses. Several groups have reported chemotactic responses of H. pylori strains to bicarbonate, ammonia/urea, bile, and various amino acids (5,9,22,40). Yet, other studies have not been able to reproduce some of these findings (3), underscoring the need for more mechanistic studies of this system.…”

“…The H. pylori genome encodes three canonical membrane-spanning chemoreceptor proteins (TlpA, TlpB, and TlpC) and one soluble chemoreceptor protein (TlpD) (3,5,9,23,30). While several groups have demonstrated chemotactic responses to a variety of substrates including urea, bicarbonate, and amino acids (3,5,22,40), the substrate specificities of these chemoreceptors have not been determined.…”

Crystallisation and Preliminary Crystallographic Analysis of Helicobacter pylori Periplasmic Binding Protein YckK

“…Serine has also been shown to behave as a chemoattractant for strains 26695 and 43504, and there is evidence that strain 26695 recognises arginine as a chemoattractant [30]. In contrast to the clinical isolates studied by Worku et al [29] , Cerda et al [30] have found no chemotactic response to alanine, histidine, or leucine in strains 26695 and 43504. Cysteine, glutamate, methionine and tryptophan also failed to elicit a chemotactic response.…”

“…Cysteine, glutamate, methionine and tryptophan also failed to elicit a chemotactic response. Furthermore, while Worku et al [29] found glutamic and aspartic acids to behave as weak chemorepellents, Cerda et al [30] reported that aspartic acid behaves as a chemoattractant of both H. pylori 26695 and 43504. Given the role of polar amino acids as chemotactic signals, it would be important to establish in the future if YckK plays a role in chemotaxis, and if so, which methyl-accepting chemotaxis protein it signals through.…”

“…Worku et al [29] reported that alanine, arginine, asparagine, glutamine, glycine, histidine, leucine, proline, tyrosine, and valine acted as chemoattractants of H. pylori isolates obtained from duodenal ulcer or dyspepsia patients. Serine has also been shown to behave as a chemoattractant for strains 26695 and 43504, and there is evidence that strain 26695 recognises arginine as a chemoattractant [30].…”