Enzymatic properties, evidence for in vivo expression, and intracellular localization of shewasin D, the pepsin homolog from Shewanella denitrificans

• Autor(a) principal: Leal, Ana Rita
• Data de Publicação: 2016
• Outros Autores: Cruz, Rui, Bur, Daniel, Huesgen, Pitter F, Faro, Rosário, Manadas, Bruno, Wlodawer, Alexander, Faro, Carlos, Simões, Isaura
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/108918; https://doi.org/10.1038/srep23869
• topic: Amino Acid Sequence; Bacterial Proteins; Biological Evolution; Cell Membrane; Conserved Sequence; Cytoplasm; Escherichia coli; Gene Expression; Hydrogen-Ion Concentration; Kinetics; Pepsin A; Pepstatins; Peptide Library; Proteolysis; Proteome; Recombinant Proteins; Sequence Homology, Amino Acid; Shewanella; Substrate Specificity

The widespread presence of pepsin-like enzymes in eukaryotes together with their relevance in the control of multiple biological processes is reflected in the large number of studies published so far for this family of enzymes. By contrast, pepsin homologs from bacteria have only recently started to be characterized. The work with recombinant shewasin A from Shewanella amazonensis provided the first documentation of this activity in prokaryotes. Here we extend our studies to shewasin D, the pepsin homolog from Shewanella denitrificans, to gain further insight into this group of bacterial peptidases that likely represent ancestral versions of modern eukaryotic pepsin-like enzymes. We demonstrate that the enzymatic properties of recombinant shewasin D are strongly reminiscent of eukaryotic pepsin homologues. We determined the specificity preferences of both shewasin D and shewasin A using proteome-derived peptide libraries and observed remarkable similarities between both shewasins and eukaryotic pepsins, in particular with BACE-1, thereby confirming their phylogenetic proximity. Moreover, we provide first evidence of expression of active shewasin D in S. denitrificans cells, confirming its activity at acidic pH and inhibition by pepstatin. Finally, our results revealed an unprecedented localization for a family A1 member by demonstrating that native shewasin D accumulates preferentially in the cytoplasm.