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Paper Chase

D-amino acids govern stationary phase cell wall remodeling in bacteria.

Science. Sep 18, 2009;325(5947):1552-5.
Lam H, Oh DC, Cava F, Takacs CN, Clardy J, de Pedro MA, Waldor MK.

Channing Laboratory, Brigham and Women's Hospital, Harvard Medical School, and Howard Hughes Medical Institute, Boston, MA 02115, USA.

Abstract:

In all known organisms, amino acids are predominantly thought to be synthesized and used as their L-enantiomers. Here, we found that bacteria produce diverse D-amino acids as well, which accumulate at millimolar concentrations in supernatants of stationary phase cultures. In Vibrio cholerae, a dedicated racemase produced D-Met and D-Leu, whereas Bacillus subtilis generated D-Tyr and D-Phe. These unusual D-amino acids appear to modulate synthesis of peptidoglycan, a strong and elastic polymer that serves as the stress-bearing component of the bacterial cell wall. D-Amino acids influenced peptidoglycan composition, amount, and strength, both by means of their incorporation into the polymer and by regulating enzymes that synthesize and modify it. Thus, synthesis of D-amino acids may be a common strategy for bacteria to adapt to changing environmental conditions.