Solid-state 13C and 15N nuclear magnetic resonance studies of alanine metabolism in Aerococcus viridans (Gaffkya homari).

G S Jacob,J Schaefer,G E Wilson

doi:10.1016/s0021-9258(18)89429-7

Abstract

Transport and metabolism of D- and L-alanine by Aerococcus viridans (Gaffkya homari) have been studied using cross-polarization magic-angle spinning 13C and 15N NMR spectroscopy of lyophilized whole cells, isolated cell walls, and crude extracts. For equimolar concentrations in the growth medium, about 10 times more D-alanine than L-alanine is transported into the cells. Examination of cells labeled with D-[13C]alanine and L-[epsilon-15N]lysine by double cross-polarization magic-angle spinning 15N NMR indicates that only about 20% of the D-alanine present in cell-wall peptidoglycan comes directly from the growth medium. The rest is produced by de novo synthesis. Most of the labeled D-alanine is found within peptidoglycan precursors or inverted to L-alanyl residues of soluble proteins.

Highlights

CARBON I C ANHYDRASEL-LYS;bottom, bovine carbonic anhydrase B. trum shows a higher carbohydrate content (signals at about 100 and 80 ppm; see Miniprint Supplement for line assignments)
From the SMonsanto Company, Physical Sciences Center, St
NMR techniques in investigations of peptidoglycan structure, and we report its utility inunraveling metabolism of the peptidoglycan amino acid components, L- and D-alanine in the Gram-positive bacterium, Aerococcus uiridans

Summary

CARBON I C ANHYDRASE

L-LYS;bottom, bovine carbonic anhydrase B. trum shows a higher carbohydrate content (signals at about 100 and 80 ppm; see Miniprint Supplement for line assignments). Trum shows a higher carbohydrate content (signals at about 100 and 80 ppm; see Miniprint Supplement for line assignments) This result indicates that theisolated cell wall is not composedsolely of classical peptidoglycan (see Miniprint Supplement for a diagram of A. uiridans peptidoglycan). Only 60% of the isolated cell-wall material is standard peptidoglycan, with the remainder unspecified carbohydrate. These findings are consistent with those of Nakel et al (1) regarding both the amino acid content of the cell wall and the carbohydrate composition of a cell-wall acid hydrolysate of A. uiriduns (ATCC 10400). Nitrogen-14 dipolar coupling broadens the amide-carbonyl lines of the carbonic-anhydrase and cell-wall spectra, relative

NATURAL ABUNDANCE

Findings

DISCUSSION