Download MendeleyStructure of the Imipenem-Hydrolyzing Class a Beta-Lactamase Sme-1 from Serratia Marcescens.
Sougakoff, W., L'Hermite, G., Billy, I., Pernot, L., Guillet, V., Naas, T., Nordmann, P., Jarlier, V., Delettre, J.(2002) Acta Crystallogr D Biol Crystallogr 58: 267
- PubMed: 11807251
- DOI: https://doi.org/10.1107/s0907444901019606
- Primary Citation of Related Structures:
1DY6 - PubMed Abstract:
The structure of the beta-lactamase SME-1 from Serratia marcescens, a class A enzyme characterized by its significant activity against imipenem, has been determined to 2.13 A resolution. The overall structure of SME-1 is similar to that of other class A beta-lactamases. In the active-site cavity, most of the residues found in SME-1 are conserved among class A beta-lactamases, except at positions 104, 105 and 237, where a tyrosine, a histidine and a serine are found, respectively, and at position 238, which is occupied by a cysteine forming a disulfide bridge with the other cysteine residue located at position 69. The crucial role played by this disulfide bridge in SME-1 was confirmed by site-directed mutagenesis of Cys69 to Ala, which resulted in a mutant unable to confer resistance to imipenem and all other beta-lactam antibiotics tested. Another striking structural feature found in SME-1 was the short distance separating the side chains of the active serine residue at position 70 and the strictly conserved glutamate at position 166, which is up to 1.4 A shorter in SME-1 compared with other class A beta-lactamases. Consequently, the SME-1 structure cannot accommodate the essential catalytic water molecule found between Ser70 and Glu166 in the other class A beta-lactamases described so far, suggesting that a significant conformational change may be necessary in SME-1 to properly position the hydrolytic water molecule involved in the hydrolysis of the acyl-enzyme intermediate.
Organizational Affiliation:
Laboratoire de Recherche Moléculaire sur les Antibiotiques (LRMA), INSERM EMI0004, Faculté de Médecine Pitié-Salpêtrière, Université Pierre et Marie Curie, 75634 Paris CEDEX 13, France.
