3ga9

Publication Abstract from PubMed

Bacillus anthracis elaborates a poly-gamma-d-glutamic acid capsule that protects bacilli from phagocytic killing during infection. The enzyme CapD generates amide bonds with peptidoglycan cross-bridges to anchor capsular material within the cell wall envelope of B. anthracis. The capsular biosynthetic pathway is essential for virulence during anthrax infections and can be targeted for anti-infective inhibition with small molecules. Here, we present the crystal structures of the gamma-glutamyltranspeptidase CapD with and without alpha-l-Glu-l-Glu dipeptide, a non-hydrolyzable analog of poly-gamma-d-glutamic acid, in the active site. Purified CapD displays transpeptidation activity in vitro, and its structure reveals an active site broadly accessible for poly-gamma-glutamate binding and processing. Using structural and biochemical information, we derive a mechanistic model for CapD catalysis whereby Pro(427), Gly(428), and Gly(429) activate the catalytic residue of the enzyme, Thr(352), and stabilize an oxyanion hole via main chain amide hydrogen bonds.

Crystal structure of Bacillus anthracis transpeptidase enzyme CapD.,Wu R, Richter S, Zhang RG, Anderson VJ, Missiakas D, Joachimiak A J Biol Chem. 2009 Sep 4;284(36):24406-14. Epub 2009 Jun 16. PMID:19535342^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.