Characterization of Bacteriophage Peptides of Pathogenic Streptococcus by LC-ESI-MS/MS: Bacteriophage Phylogenomics and Their Relationship to Their Host.

Ana G Abril,Pilar Calo-Mata,Jose L R Rama,Tomás G Villa,Karola Böhme,Mónica Carrera,Benito Cañas,Jorge Barros-Velázquez

doi:10.3389/fmicb.2020.01241

Abstract

The present work focuses on LC-ESI-MS/MS (liquid chromatography-electrospray ionization-tandem mass spectrometry) analysis of phage-origin tryptic digestion peptides from mastitis-causing Streptococcus spp. isolated from milk. A total of 2,546 non-redundant peptides belonging to 1,890 proteins were identified and analyzed. Among them, 65 phage-origin peptides were determined as specific Streptococcus spp. peptides. These peptides belong to proteins such as phage repressors, phage endopeptidases, structural phage proteins, and uncharacterized phage proteins. Studies involving bacteriophage phylogeny and the relationship between phages encoding the peptides determined and the bacteria they infect were also performed. The results show how specific peptides are present in closely related phages, and a link exists between bacteriophage phylogeny and the Streptococcus spp. they infect. Moreover, the phage peptide M∗ATNLGQAYVQIM∗PSAK is unique and specific for Streptococcus agalactiae. These results revealed that diagnostic peptides, among others, could be useful for the identification and characterization of mastitis-causing Streptococcus spp., particularly peptides that belong to specific functional proteins, such as phage-origin proteins, because of their specificity to bacterial hosts.

Highlights

Streptococcus spp. are among the main mastitis pathogens present in dairy products (Forsman et al, 1997; Böhme et al, 2012)
LC-ESI-MS/MS techniques have been employed for the identification and detection of bacterial bacteriophages such as the bacteriophage lambda (Serafim et al, 2017)
Proteomics techniques using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) instruments have been used for the analysis and detection of pathogenic bacterial pathogen strains based on specific diagnostic peptides (Lasch et al, 2009; Böhme et al, 2011, 2012; Branquinho et al, 2014; Quintela-Baluja et al, 2014; Calo-Mata et al, 2016; Pfrunder et al, 2016; Carrera et al, 2017)

Summary

Introduction

Streptococcus spp. are among the main mastitis pathogens present in dairy products (Forsman et al, 1997; Böhme et al, 2012). The major species involved in both clinical and subclinical mastitis are Streptococcus agalactiae, Streptococcus canis, Streptococcus dysgalactiae and Streptococcus uberis (Lundberg et al, 2014; Richards et al, 2014). It is well known that Streptococcus spp. may carry temperate bacteriophages in their genomes (Brüssow and Desiere, 2001; Romero et al, 2004; Fortier and Sekulovic, 2013). These phages are usually integrated into bacterial chromosomes as prophages, wherein they may provide new and beneficial properties to the host, or in contrast, they may disrupt genes, affecting their expression (Fortier and Sekulovic, 2013). It is evident that the interaction of streptococcal species with bacteriophages may greatly alter the variability in bacterial populations (Feiner et al, 2015)

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