Identification and analysis of a novel serine β-lactamase-like plant protein by a bioinformatic approach

Abstract

We have searched through plant databases for nucleotide and protein sequences sharing a significant similarity to bacterial serine β-lactamases and metazoan LACTB. The search resulted in the identification of novel serine β-lactamase homologues in both Gymno- and Angiosperms. However, unlike bacterial β- lactamases and metazoan LACTB, plant homologues are dual domain proteins composed of an N-terminal ABC1 domain containing serine / threonine protein kinase motifs, followed by a C-terminal β-lactamase domain containing the active site motifs present in all serine β-lactamases. Multiple sequence alignments and secondary structure modelling of the β-lactamase domain revealed conserved regions that correspond to structural elements required for the serine protease active center formation. On the basis of sequence homology and secondary structure conservation, we propose that the chimeric plant protein is involved in apoptotic processes through its serine protease and serine /threonine protein kinase activity. Keywords: serine β-lactamases, LACTB, ABC1, computational modelling, apoptosis