4OQI

Crystal structure of stabilized TEM-1 beta-lactamase variant v.13 carrying R164S/G238S mutations

Summary for 4OQI

• Entry DOI: 10.2210/pdb4oqi/pdb
• Related: 4IBR 4IBX 4OP5 4OP8 4OPQ 4OPR 4OPY 4OPZ 4OQ0 4OQG 4OQH
• Descriptor: TEM-94 ES-beta-lactamase, CALCIUM ION, SULFATE ION, ... (4 entities in total)
• Functional Keywords: beta-lctamase, hydrolase-hydrolase inhibitor complex, hydrolase/hydrolase inhibitor
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 28866.83

Authors

Dellus-Gur, E.,Elias, M.,Fraser, J.S.,Tawfik, D.S. (deposition date: 2014-02-09, release date: 2015-05-20, Last modification date: 2018-01-17)

Primary citation

Dellus-Gur, E.,Elias, M.,Caselli, E.,Prati, F.,Salverda, M.L.,de Visser, J.A.,Fraser, J.S.,Tawfik, D.S.
Negative Epistasis and Evolvability in TEM-1 beta-Lactamase--The Thin Line between an Enzyme's Conformational Freedom and Disorder.
J. Mol. Biol., 427:2396-2409, 2015

PubMed Abstract: Epistasis is a key factor in evolution since it determines which combinations of mutations provide adaptive solutions and which mutational pathways toward these solutions are accessible by natural selection. There is growing evidence for the pervasiveness of sign epistasis--a complete reversion of mutational effects, particularly in protein evolution--yet its molecular basis remains poorly understood. We describe the structural basis of sign epistasis between G238S and R164S, two adaptive mutations in TEM-1 β-lactamase--an enzyme that endows antibiotics resistance. Separated by 10 Å, these mutations initiate two separate trajectories toward increased hydrolysis rates and resistance toward second and third-generation cephalosporins antibiotics. Both mutations allow the enzyme's active site to adopt alternative conformations and accommodate the new antibiotics. By solving the corresponding set of crystal structures, we found that R164S causes local disorder whereas G238S induces discrete conformations. When combined, the mutations in 238 and 164 induce local disorder whereby nonproductive conformations that perturb the enzyme's catalytic preorganization dominate. Specifically, Asn170 that coordinates the deacylating water molecule is misaligned, in both the free form and the inhibitor-bound double mutant. This local disorder is not restored by stabilizing global suppressor mutations and thus leads to an evolutionary cul-de-sac. Conformational dynamism therefore underlines the reshaping potential of protein's structures and functions but also limits protein evolvability because of the fragility of the interactions networks that maintain protein structures.

PubMed: 26004540
DOI: 10.1016/j.jmb.2015.05.011

Experimental method

X-RAY DIFFRACTION (1.13 Å)