The Morphological Transition ofHelicobacter pyloriCells from Spiral to Coccoid Is Preceded by a Substantial Modification of the Cell Wall

Abstract

The peptidoglycan (murein) of Helicobacter pylori has been investigated by high-performance liquid chromatography and mass spectrometric techniques. Murein from H. pyloricorresponded to the A1γ chemotype, but the muropeptide elution patterns were substantially different from the one forEscherichia coli in that the former produced high proportions of muropeptides with a pentapeptide side chain (about 60 mol%), with Gly residues as the C-terminal amino acid (5 to 10 mol%), and with (1→6)anhydro-N-acetylmuramic acid (13 to 18 mol%). H. pylori murein also lacks murein-bound lipoprotein, trimeric muropeptides, and (l-d) cross-linked muropeptides. Cessation of growth and transition to coccoid shape triggered an increase inN-acetylglucosaminyl-N-acetylmuramyl–l-Ala–d-Glu (approximately 20 mol%), apparently at the expense of monomeric muropeptides with tri- and tetrapeptide side chains. Muropeptides with (1→6)anhydro-muramic acid and with Gly were also more abundant in resting cells.

Alteration in the composition of cholesteryl glucosides and other lipids in undergoing morphological change from spiral to coccoid form

“…In a recent report describing the alteration in bacterial material associated with morphological change in H. pylori, the cell wall of the coccoid form has been shown to be structured differently from that of the spiral form [6]. The bacterial cell wall is an important organ in forming the framework of the cells, and lipids are essential in maintaining membrane structure and function.…”

Peptidoglycan structure and architecture

“…Variations in peptidoglycan fine structure have also been associated with bacterial pathogenesis in a number of cases. Well-documented examples are the changes exhibited by peptidoglycan in Neisseria gonorrhoeae peptidoglycan related to secretion of cytotoxin (Cloud & Dillard, 2002); in H. pylori associated with morphological transitions (Costa et al, 1999); and in Salmonella typhimurium associated with intracellular colonization of epithelial cells (Quintela et al, 1997).…”

Inhibition of the resuscitation from the viable but non‐culturable state in Enterococcus faecalis

“…recovery of cell division) has been described at least in part of the population upon restoration of suitable environmental conditions (Oliver and Bockian, 1995;Jians and Chai, 1996;Steinert et al, 1997;Lleò et al, 2000a). Furthermore, alterations of the cell walls of both Gram-positive (Signoretto et al, 2000) and Gram-negative (Costa et al, 1999;Signoretto et al, 2002) bacteria have been described in connection with the VBNC state in order to render cells more resistant to environmental stresses. Thus, the VBNC state could be seen as a quiescent form of life of cells exposed to environmental stresses pending more appropriate conditions.…”