title: N Glycolylation of the nucleotide precursors of peptidoglycan biosynthesis of Mycobacterium spp. is altered by drug treatment.
abstract: The peptidoglycan of Mycobacterium spp. reportedly has some unique features, including the occurrence of N-glycolylmuramic rather than N-acetylmuramic acid. However, very little is known of the actual biosynthesis of mycobacterial peptidoglycan, including the extent and origin of N glycolylation. In the present work, we have isolated and analyzed muramic acid residues located in peptidoglycan and UDP-linked precursors of peptidoglycan from Mycobacterium tuberculosis and Mycobacterium smegmatis. The muramic acid residues isolated from the mature peptidoglycan of both species were shown to be a mixture of the N-acetyl and N-glycolyl derivatives, not solely the N-glycolylated product as generally reported. The isolated UDP-linked N-acylmuramyl-pentapeptide precursor molecules also contain a mixture of N-acetyl and N-glycolyl muramyl residues in apparent contrast to previous observations in which the precursors isolated after treatment with d-cycloserine consisted entirely of N-glycolyl muropeptides. However, nucleotide-linked peptidoglycan precursors isolated from M. tuberculosis treated with d-cycloserine contained only N-glycolylmuramyl-tripeptide precursors, whereas those from similarly treated M. smegmatis consisted of a mixture of N-glycolylated and N-acetylated residues. The full pentapeptide intermediate, isolated following vancomycin treatment of M. smegmatis, consisted of the N-glycolyl derivative only, whereas the corresponding M. tuberculosis intermediate was a mixture of both the N-glycolyl and N-acetyl products. Thus, treatment with vancomycin and d-cylcoserine not only caused an accumulation of nucleotide-linked intermediate compounds but also altered their glycolylation status, possibly by altering the normal equilibrium maintained by de novo biosynthesis and peptidoglycan recycling.
authors.affiliation: Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Sebabrata
authors.initials: S
authors.lastname: Mahapatra
authors.forename: Hataichanok
authors.initials: H
authors.lastname: Scherman
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Brennan
authors.forename: Dean C
authors.initials: DC
authors.lastname: Crick
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000904:Antibiotics, Antitubercular / Q000494:pharmacology; D003523:Cycloserine / Q000494:pharmacology; D015394:Molecular Structure; D020102:Mycobacterium smegmatis / Q000187:drug effects* / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000378:metabolism*; D009711:Nucleotides / Q000378:metabolism*; D010457:Peptidoglycan / Q000096:biosynthesis* / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000904:Antibiotics, Antitubercular; D009711:Nucleotides; D010457:Peptidoglycan; D014640:Vancomycin; D003523:Cycloserine