[Trans-gram gene transfer: the case of beta-lactamases].
Lateral or horizontal gene transfer is a phenomenon that has influenced the evolution of microorganisms. Despite the evolutionary trend toward genetic isolation, lateral transfer seems to take place relatively frequently, bridging the gap between very separate species. The acquisition of foreign genes may have accelerated in recent years because of the increase in the adaptive needs of bacteria, particularly through the use of antibiotics. Transfer of genes encoding beta-lactamases from Gram-positive to Gram-negative bacteria (trans-gram transfer) may be suggested on the basis of sequence analysis. We found that the sequences of the beta-lactamases BRO-1 and ACl-1, from the Gram-negative bacterial organisms Moraxella and Acidaminococcus, respectively are abnormally placed among sequences from Gram-positive beta-lactamases in phylogenetic trees. In both cases, the topology of the enzyme (attached to the cellular membrane), the structure of the signal peptide, and the Shine-Dalgarno region suggest that these enzymes originated from Gram-positive organisms. Results remain inconclusive for Haemophilus ROB-1 beta-lactamase.
Galán
J C
JC
Servicio de Microbiología, Hospital Ramón y Cajal, Madrid. jgalanm@hrc.insalud.es
D022761:Gene Transfer, Horizontal; D006090:Gram-Negative Bacteria / Q000235:genetics*; D006094:Gram-Positive Bacteria / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics*
D001618:beta-Lactamases