TY - JOUR
T1 - Structural basis for the extended substrate spectrum of AmpC BER and structure-guided discovery of the inhibition activity of citrate against the class C β-lactamases AmpC BER and CMY-10
AU - Na, Jung Hyun
AU - Cha, Sun Shin
N1 - Funding Information:
This study was supported by the National Research Foundation of Korea (grants NRF-2015R1A2A2A01004168 and NRF- 2015M1A5A1037480).
Publisher Copyright:
© International Union of Crystallography, 2016.
PY - 2016
Y1 - 2016
N2 - AmpC BER is an extended substrate spectrum class C β-lactamase with a two-amino-acid insertion in the R2 loop compared with AmpC EC2. The crystal structures of AmpC BER (S64A mutant) and AmpC EC2 were determined. Structural comparison of the two proteins revealed that the insertion increases the conformational flexibility of the R2 loop. Two citrate molecules originating from the crystallization solution were observed in the active site of the S64A mutant. One citrate molecule makes extensive interactions with active-site residues that are highly conserved among class C β-lactamases, whereas the other one is weakly bound. Based on this structural observation, it is demonstrated that citrate, a primary metabolite that is widely used as a food additive, is a competitive inhibitor of two class C β-lactamases (AmpC BER and CMY-10). Consequently, the data indicate enhancement of the flexibility of the R2 loop as an operative strategy for molecular evolution of extended-spectrum class C β-lactamases, and also suggest that the citrate scaffold is recognized by the active sites of class C β-lactamases.
AB - AmpC BER is an extended substrate spectrum class C β-lactamase with a two-amino-acid insertion in the R2 loop compared with AmpC EC2. The crystal structures of AmpC BER (S64A mutant) and AmpC EC2 were determined. Structural comparison of the two proteins revealed that the insertion increases the conformational flexibility of the R2 loop. Two citrate molecules originating from the crystallization solution were observed in the active site of the S64A mutant. One citrate molecule makes extensive interactions with active-site residues that are highly conserved among class C β-lactamases, whereas the other one is weakly bound. Based on this structural observation, it is demonstrated that citrate, a primary metabolite that is widely used as a food additive, is a competitive inhibitor of two class C β-lactamases (AmpC BER and CMY-10). Consequently, the data indicate enhancement of the flexibility of the R2 loop as an operative strategy for molecular evolution of extended-spectrum class C β-lactamases, and also suggest that the citrate scaffold is recognized by the active sites of class C β-lactamases.
KW - citrate
KW - class C β-lactamases
KW - competitive inhibition
KW - crystal structure
KW - extension of substrate spectrum
KW - flexibility of the R2 loop
UR - http://www.scopus.com/inward/record.url?scp=85008884172&partnerID=8YFLogxK
U2 - 10.1107/S2059798316011311
DO - 10.1107/S2059798316011311
M3 - Article
C2 - 27487828
AN - SCOPUS:85008884172
SN - 2059-7983
VL - 72
SP - 976
EP - 985
JO - Acta Crystallographica Section D: Structural Biology
JF - Acta Crystallographica Section D: Structural Biology
IS - 8
ER -