Characterization of Maltocin P28, a Novel Phage Tail-Like Bacteriocin from Stenotrophomonas maltophilia

Abstract

bStenotrophomonas maltophilia is an important global opportunistic pathogen for which limited therapeutics are available because of the emergence of multidrug-resistant strains. A novel bacteriocin, maltocin P28, which is produced by S. maltophilia strain P28, may be the first identified phage tail-like bacteriocin from S. maltophilia. Maltocin P28 resembles a contractile but nonflexible phage tail structure based on electron microscopy, and it is sensitive to trypsin, proteinase K, and heat. SDS-PAGE analysis of maltocin P28 revealed two major protein bands of approximately 43 and 20 kDa. The N-terminal amino acid residues of these two major subunits were sequenced, and the maltocin P28 gene cluster was located on the S. maltophilia P28 chromosome. Our sequence analysis results indicate that this maltocin gene cluster consists of 23 open reading frames (ORFs), and that its gene organization is similar to that of the P2 phage genome and R2 pyocin gene cluster. ORF17 and ORF18 encode the two major structural proteins, which correspond to gpFI (tail sheath) and gpFII (tail tube) of P2 phage, respectively. We found that maltocin P28 had bactericidal activity against 38 of 81 tested S. maltophilia strains. Therefore, maltocin P28 is a promising therapeutic substitute for antibiotics for S. maltophilia infections.

Characterization of maltocin S16, a phage tail‐like bacteriocin with antibacterial activity againstStenotrophomonas maltophiliaandEscherichia coli

“…Twenty‐three ORFs were proposed to encode maltocin S16‐related proteins, all of which were transcribed in the same direction (Table ). The genetic organization of maltocin S16 was the same as that of maltocin P28 (Liu et al ) and was similar to the R2 pyocin gene cluster and P2 phage genome (Nakayama et al ; Christie and Calendar ).…”

The Tailocin Tale: Peeling off Phage Tails

“…This conclusion is contrary to common belief and not consistent with published field work [5]. The example cited by Loguercio and Argôlo-Filho refers to plant-colonizing Bt strains [6] -one could argue that there is less of a fitness cost when the bacteria are not reproducing to any significant extent. (iv) That enterotoxins are not required for insect toxicity.…”

“…R-type tailocins also occur in plant-associated pseudomonad species [3,4]. Morphologically similar bacteriocins have been identified in several other g-proteobacterial genera, representing species with different lifestyles, such as carotovoricin of the phytopathogen Pectobacterium carotovorum causing soft rot, xenorhabdicin of the entomopathogenic nematode symbiont Xenorhabdus nematophila, and maltocin of the opportunistic pathogen Stenotrophomonas maltophilia [5,6]. Bactericidal tailocins are not confined to Gram-negative bacteria, as their general morphology is also conserved in a bacteriocin produced by the Gram-positive pathogen Clostridium difficile [7].…”

Biological Cost of Pyocin Production during the SOS Response in Pseudomonas aeruginosa

“…This raises the possibility that R2 pyocin might restrict the conditions under which P. aeruginosa can grow because the expression of B-band O-antigen synthesis genes must be maintained to resist R2 pyocin-mediated killing. Many bacteria produce HMW or phage tail-like bacteriocins (44)(45)(46)(47)(48)(49)(50)(51)(52), and it is likely that the genes that confer resistance and synthesize the HMW bacteriocin are not genetically linked. These species may also have to balance the benefits of producing HMW bacteriocins with the risks that may pose under certain conditions.…”