About this Research Topic
Life on the earth uses exclusively L-amino acids for molecular architecture of proteins. D-amino acids are chiral form of L-amino acids and are known to function in non-ribosomal physiology. Although all proteinogenic amino acids except for glycine have chiral forms, life appears to choose one of the enantiomers in biological processes. Among all domains of life, bacteria have the largest capacity to utilize D-amino acids. Bacteria have been described to synthesize more than 10 kinds of D-amino acids, most commonly D-alanine and D-glutamate for crosslinking within the peptidoglycan cell wall. But, cell walls found in other life, such as archaea or plants/fungi in eukaryote, are not composed with D-amino acids.
Furthermore, extracellular D-amino acids released from bacteria regulate remodeling of bacterial cell wall and are thought to function in communication among bacteria to accommodate changing environment. Besides structural function in bacterial cell wall, D-amino acids have been associated to growth fitness and to processes such as biofilm development, spore germination and signaling.
Bacteria develop unique metabolic pathways for multiple D-amino acids, such as amino acid racemization or epimerization. Therefore a variety of D-amino acids in nature can be regarded as molecules originated from bacteria and have been targeted for development of new antibiotics or bacteria-specific markers.
More recently, D-amino acids in interface between bacteria and mammals, such as mammalian gut, are highlighted. Mammals appear to recognize bacteria through metabolizing bacterial D-amino acids in the interface and modulate innate immune system. Moreover, a D-amino acid produced by probiotic bacteria has been identified to modify immune tolerance and ameliorate allergic inflammation in mammalian airway.
This Research Topic focuses on any aspect of microbial D-amino acids including enzyme biochemistry, metabolism, bacterial physiology, drug/marker development, microbiome, host-microbe interaction, and mammalian physiology. Furthermore, we are also open for food sciences focusing on D-amino acids created e.g. through fermentation by microorganism. We welcome the contribution of original research articles as well as reviews.
Keywords: D-amino acid, metabolism, cell wall, peptidoglycan, host-microbe interaction
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