Biosynthesis of D-alanyl-lipoteichoic acid by Lactobacillus casei: interchain transacylation of D-alanyl ester residues

Abstract

Lipoteichoic acid (LTA) from Lactobacilus casei contains poly(glycerophosphate) substituted with D-alanyl ester residues. The distribution of these residues in the in vitro-synthesized polymer is uniform. Esterification of LTA with D-alanine may occur in one of two modes: (i) addition at random or (ii) addition at a defined locus in the poly(glycerophosphate) chain followed by redistribution of the ester residues. A time-dependent transacylation of these residues from D_[14C]alanyl-lipophilic LTA to hydrophilic acceptor was observed. The hydrophilic acceptor was characterized as D-alanyl-hydrophilic LTA. This transacylation requires neither ATP nor the D-alanine incorporation system, i.e., the D-alanine activating enzyme and D-alanine:membrane acceptor ligase. No evidence for an enzyme-catalyzed transacylation reaction was observed. We propose that this process of transacylation may be responsible for the redistribution of D-alanyl residues after esterification to the poly(glycerophosphate). As a result, it is difficult to distinguish between these proposed modes of addition.on July 16, 2020 by guest

Characterization and Discrimination of Gram-Positive Bacteria Using Raman Spectroscopy with the Aid of Principal Component Analysis

“…Moreover, it was found that the AgNPs mainly interact with the cell wall components, and the SERS spectra of L. monocytogenes contain all nine marker bands [ 44 ] in both SERS detection approaches ( Figure 3 ): 1048/1047 cm −1 in-plane CH bending mode [ 14 ], the band at 1123/1145 cm −1 is the result of CN and CC stretching in carbohydrates [ 14 , 56 ] or in lipids [ 60 ], or even the aromatic amino acids’ deformation in proteins [ 61 ], the band at 1221 cm −1 is assigned to amide III [ 57 ], while the band at 1291/1293 cm −1 represents CH deformations in proteins [ 57 ]. The bands; at 1363/1359 cm −1 were assigned to the CH deformations of proteins or ν(COO − ) symmetric deformations [ 58 , 60 ], whereas the 1428/1427 and 1449 cm −1 bands are due to CH 2 deformations of saturated lipids [ 14 , 35 ]. The group of bands in the region 1400–1500 cm −1 is due to (CC) stretching vibrations, to (CH 2 ) twist vibrations and (CH 3 ) or (CH 2 ) deformations, respectively fatty acids [ 62 ].…”

“…According to PC-4— Figure S4 a, PC-6— Figure S4 b and PC-7— Figure S4 c loadings plots, one SERS band that participates inthe discrimination of the two bacteria is the adenine band located at 730 cm −1 in the a priori SERS spectrum of L. casei. The discrimination is based also on the AgNPs’ interaction with the L. monocytogenes cell wall components, with bands at 1363 cm −1 , ascribed to CH deformations of proteins or ν(COO − ) symmetric deformations [ 58 , 60 ], and at 1428 and 1449 cm −1 bands, due to CH 2 deformations of saturated lipids [ 35 ] (PC-4— Figure S4 a and PC-7— Figure S4 c, respectively). PC-6 takes into account the band at 1176 cm −1 , ascribed to phenylalanine, which appears only in the SERS spectra of L. monocytogenes as a distinct spectral feature relevant in the discrimination process.…”

“…The separation between L. casei and L. monocytogenes is made along PC-2 and PC-3 axes, and explains 20% and 6%, respectively, of the total variance of the data set. According to the PC loading plots ( Figure S5 a–c), the spectral differences that contribute to the discrimination between the species are related to the 731 cm −1 adenine vibration band and the SERS bands assigned to CC, CO, COH deformations in carbohydrates [ 36 ] or C–C stretching in lipids [ 60 ] (the band at 1145 cm −1 from the L. monocytogenes spectrum), to amide III [ 57 ] (the band at 1221 cm −1 ), which is absent in the L. casei in situ SERS spectrum, to CH deformations in proteins [ 57 ] (the band at 1293, 1359 cm −1 ) and to CH 2 deformations of saturated lipids [ 35 ] (the 1427 and 1449 cm −1 bands).…”

The Staphylococcus aureus Methicillin Resistance Factor FmtA Is a d -Amino Esterase That Acts on Teichoic Acids

“…Evidence for alanyl turnover in S. aureus LTAs has been reported by Haas et al, and their study determined that the t 1/2 of alanyl turnover in S. aureus LTA was 37 min ( 64 ), which is in remarkable agreement with our estimated t 1/2 . By comparing the kinetics of alanyl turnover in S. aureus LTA to the kinetics of alanyl turnover in a base-catalyzed reaction ( 53 ), Haas et al suggested that d -alanyl removal from LTA is likely to be an enzyme-catalyzed process ( 64 ). Our study suggests that FmtA is the enzyme that catalyzes the alanyl turnover of teichoic acids.…”

“…First, it has been proposed that the d -Ala of LTAs serves as the d -Ala source for d -alanylation of WTAs ( 33 ), but no study has shown how d -Ala is removed from LTA. Although it has been reported that d -Ala can spontaneously be removed from LTA, these processes are very slow ( 53 ). Second, studies have shown that the d -Ala content in teichoic acids is affected by a number of environmental factors, such as salt concentration, pH, and temperature ( 54 – 56 ), which suggests that, under certain environmental conditions, d -Ala from teichoic acids must be removed ( 54 ).…”