Changes in peptidoglycan structure and metabolism during differentiation of  Proteus mirabilis  into swarmer cells.
The O-acetylation of peptidoglycan in Gram-negative bacteria occurs specifically at the C-6 hydroxyl group of muramoyl residues. The level of peptidoglycan O-acetylation was found to decrease from 51% to 29% upon differentiation of  Proteus mirabilis  vegetative cells to swarmers. This decrease was accompanied by a change in the muropeptide composition of the peptidoglycan. In particular, the content of anhydromuropeptides increased, while the amount of Lys-Lys-muropeptides arising from bound lipoprotein decreased. These changes together with a shift in proportion of larger muropeptides suggested a decrease in average chain length of the muropeptides from swarmer cells. Zymography using SDS-PAGE gels containing either O-acetylated or chemically de-O-acetylated peptidoglycan was used to monitor the activity of specific autolysins during the differentiation of vegetative to swarming cells of P. mirabilis. A 43 kDa autolysin with increased specificity for O-acetylated peptidoglycan was detected in vegetative cells, but its activity appeared to decrease as the cells began to differentiate, while the levels of 3 other autolysins with apparent specificity for non-O-acetylated peptidoglycan increased. These changes are discussed in relation to the autolysin profile of the bacteria and the changes in peptidoglycan composition with cell differentiation.
Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
Hendrik
H
Strating
Chris
C
Vandenende
Anthony J
AJ
Clarke
D000107:Acetylation; D002454:Cell Differentiation; D004591:Electrophoresis, Polyacrylamide Gel; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000378:metabolism; D010457:Peptidoglycan / Q000737:chemistry* / Q000378:metabolism*; D011513:Proteus mirabilis / Q000166:cytology / Q000378:metabolism / Q000502:physiology*
D010457:Peptidoglycan; D009238:N-Acetylmuramoyl-L-alanine Amidase