Alanine metabolism in Bacillus subtilis

Abstract

Bacterial cell growth requires the coordinated synthesis of all the metabolites necessary for the enlargement of the cell. One essential component of the bacterial cell wall that is unique to bacteria is D-alanine. This amino acid isomer is universally used by bacteria in the synthesis of the peptidoglycan (PG) where it acts as a substrate for penicillin binding protein-mediated crosslinking of the glycan strands (Hernandez & Cava, 2016;Lam et al., 2009). Also, in Grampositive bacteria, D-alanine is used to modify the teichoic acids, which are present as a second major polymeric component of the cell wall and membrane (Perego et al., 1995;Wecke et al., 1996). The other isomeric form, L-alanine, is an essential precursor for protein synthesis.Bacteria obtain D-alanine primarily by converting L-alanine by racemization. L-alanine, on the other hand, can be biosynthesized by the cell, or assimilated by the cell if present in the extracellular environment. Alanine synthesis and metabolism is increasingly being exploited for antibacterial and industrial applications. For example, exogenous L-alanine has been shown to increase the susceptibility of some pathogens to antibiotics (Peng et al., 2015); D-alanine can

Inhibition of Campylobacter jejuni Biofilm Formation by D-Amino Acids

“…We observed that D-met, and D-trp, have a significant effect on triggering the disassembly of the biofilms at concentrations of ≥5 mM, similar to that observed for S. aureus and P. aeruginosa [43]. It is important to note that the inhibitory effect on the growth of C. jejuni by DAs, except D-met, could be reversed by D-ala, similar to that observed for B. subtilis, M. tuberculosis and Escherichia coli [38,39,44,45].…”

“…To explore that possibility, we interrogated the effect of DAs and LAs on the expression level of two genes in C. jejuni; alanine racemase (alr) (Cj0905c), and D-Ala-D-Ala ligase (ddlA) (Cj0798c) [48,49]. Both genes are encoding enzymes involved in an important step in D-Ala metabolism [44,50], which is essential for the synthesis of PG of the bacterial cell wall [45,51,52]. Two main reactions are involved in this process, first the conversion of L-Ala to D-Ala by alanine racemase (alr), and the formation of D-alanyl-D-alanine dipeptide (D-Ala-D-Ala) from D-ala by D-alanine-D-alanine ligase (ddl) [53].…”

Simultaneous Presence of Bacteriochlorophyll and Xanthorhodopsin Genes in a Freshwater Bacterium

“…The most downregulated gene under both conditions coded for the alanine dehydrogenase (E2E30_RS03695; EC 1.4.1.1). In bacteria, this enzyme is crucial for the utilization of l- alanine as an energy source and is also involved in the transcriptional regulation of alanine metabolism ( 50 ). A complete list of up- and downregulated genes can be found in Table S5 .…”

The current state of SubtiWiki, the database for the model organism Bacillus subtilis

“…The latest updates reflect intensive research to identify novel transporters in B. subtilis . These include transporters for bicarbonate (NdhF-YbcC) ( 20 , 21 ) and several amino acids, including alanine (AlaP), glutamate and serine (both AimA), and the toxic analogon glyphosate (GltT) ( 22–25 ).…”