A Genotype-Phenotype Correlation Study of SHV β-Lactamases Offers New Insight into SHV Resistance Profiles.

The SHV β-lactamases (BLs) have undergone strong allele diversification that has changed their substrate specificities. Based on 147 NCBI entries for SHV alleles, mathematical models predicted 5 positions as relevant for the β-lactamase inhibitor (BLI)-resistant (2br) phenotype, 12 positions as relevant for the extended-spectrum BL (ESBL) (2be) phenotype, and 2 positions as related solely to the narrow-spectrum (2b) phenotype. These positions and six additional positions described in other studies (including one promoter mutation) were systematically substituted and investigated for their substrate specificities in a BL-free background, representing, to our knowledge, the most comprehensive substrate and substitution analysis for SHV alleles to date.