PREDICTED SECONDARY STRUCTURES OF FOUR PENICILLIN BETA‐LACTAMASES AND A COMPARISON WITH TWO LYSOZYMES

Abstract

We have predicted the secondary structures of four beta-lactamases /Bacillus cereus, Bacillus licheniformis, Staphylococcus aureus, and Escherichia coli R-TEM) by the statistical method of Chou & Fasman as well as by the information theory method of Garnier et al. The secondary structures of all four beta-lactamases are of the alpha/beta type (Levitt & Chothias's nomenclature), with helices at N- and C-termini. There are about eight short regions each of alpha-helical (30–50%) and beta-strand (10–20%) structure separated by about 20 reverse turns. The conformation of the Gram-positive and Gram-negative beta-lactamases are generally similar although a few differences are predicted between the S.aureus and E.coli structures. Surprisingly, the two bacilli structures differ significantly in three short regions. In all four enzymes the region near the catalytically-implicated tyrosine has similar secondary structure. The secondary structure of hen egg white lysozyme, a penicillin-binding enzyme, as well as T4 phage lysozyme, has similarities to the N-terminal half of the penicillin-destroying beta-lactamases.