Antibacterial Activity of Stenotrophomonas maltophilia Endolysin P28 against both Gram-positive and Gram-negative Bacteria

Abstract

Maltocin P28 is a phage-tail like bacteriocin produced by Stenotrophomonas maltophilia P28. The ORF8 of maltocin P28 gene cluster is predicted to encode an endolysin and we name it endolysin P28. Sequence analysis revealed that it contains the lysozyme_like superfamily conserved domain. Endolysin P28 has the four consensus motifs as that of Escherichia coli phage lambda gpR. In this study, endolysin P28 was expressed in E. coli BL21 (DE3) and purified with a C-terminal oligo-histidine tag. The antibacterial activity of endolysin P28 increased as the temperature rose from 25 to 45°C. Thermostability assays showed that endolysin P28 was stable up to 50°C, while its residual activity was reduced by 55% after treatment at 70°C for 30 min. Acidity and high salinity could enhance its antibacterial activity. Endolysin P28 exhibited a broad antibacterial activity against 14 out of 16 tested Gram-positive and Gram-negative bacteria besides S. maltophilia. Moreover, it could effectively lyse intact Gram-negative bacteria in the absence of ethylenediaminetetraacetic acid as an outer membrane permeabilizer. Therefore, the characteristics of endolysin P28 make it a potential therapeutic agent against multi-drug-resistant pathogens.

Membrane vesicle secretion and prophage induction in multidrug‐resistant Stenotrophomonas maltophilia in response to ciprofloxacin stress

“…Besides bacteriophages observed by electron microscopy, phage-related proteins that are identical to maltocin were identified as part of the ciprofloxacininduced MV cargo. Maltocin was described as a bactericidal tailocin expressed by S. maltophilia P28 (Liu et al, 2013;Dong et al, 2015). Tailocins are headless bacteriophage structures (replication-deficient), that are expressed under certain conditions and are able to establish a species-specific delivery of bacteriocins (Ghequire and De Mot, 2015).…”

“…The proteomic analysis revealed the presence of a cluster of phage-related proteins that was solely identified in ciprofloxacin-induced MV isolates: a phage tail protein, a major tail tube protein, a major tail sheath protein, a baseplate assembly protein, and a phage-related protein. This cluster of phage(-like) proteins corresponds to maltocin, a tailocin formerly characterized in S. maltophilia P28 and which showed a bactericidal effect against other S. maltophilia strains and other species like P. aeruginosa, Bacillus cereus and S. aureus (Liu et al, 2013;Dong et al, 2015).…”

Lytic transglycosylases: concinnity in concision of the bacterial cell wall

“…A bacteriophage (maltocin P28) isolated from S. maltophilia encodes among its 23 ORFs a Family 4 LT (Endolysin P28) in its ORF8 having 57% sequence identity, 84% query coverage, compared to endolysin λ of E. coli. Endolysin P28 degrades peptidoglycan with sufficient catalytic competency as to show bactericidal activity against many Gram-negative bacteria (Dong et al , 2015). …”

Stenotrophomonas-Like Bacteria Are Widespread Symbionts in Cone Snail Venom Ducts

“…Of particular relevance to pharmaceutical potential, Stenotrophomonas spp. sometimes produce toxic small molecules, such as maltophilin (13) and lytic enzymes (14). They are also well known for the production of secreted protease (15); speculatively, this could play a role in the interaction between symbiotic bacteria and peptidic venom components.…”