Tail tubular protein A: a dual-function tail protein of Klebsiella pneumoniae bacteriophage KP32

Abstract

Tail tubular protein A (TTPA) is a structural tail protein of Klebsiella pneumoniae bacteriophage KP32, and is responsible for adhering the bacteriophage to host cells. For the first time, we found that TTPA also exhibits lytic activity towards capsular exopolysaccharide (EPS) of the multiresistant clinical strain of Klebsiella pneumoniae, PCM2713, and thus should be regarded as a dual-function macromolecule that exhibits both structural and enzymatic actions. Here, we present our crystallographic and enzymatic studies of TTPA. TTPA was crystallized and X-ray diffraction data were collected to a resolution of 1.9 Å. In the crystal, TTPA molecules were found to adopt a tetrameric structure with α-helical domains on one side and β-strands and loops on the other. The novel crystal structure of TTPA resembles those of the bacteriophage T7 tail protein gp11 and gp4 of bacteriophage P22, but TTPA contains an additional antiparallel β-sheet carrying a lectin-like domain that could be responsible for EPS binding. The enzymatic activity of TTPA may reflect the presence of a peptidoglycan hydrolase domain in the α-helical region (amino acid residues 126 to 173). These novel results provide new insights into the enzymatic mechanism through which TTPA acts on polysaccharides.

Identification of a novel bacterial receptor that binds tail tubular proteins and mediates phage infection of Vibrio parahaemolyticus

“…TTPB forms the end of the tail below TTPA [15]. TTPA in Klebsiella pneumoniae bacteriophage KP32 has also been shown to have enzymatic activity to hydrolyze bacterial polysaccharides [42,43], but the role of TTPA in phage adsorption has not been experimentally shown. To the best of our knowledge, this study is the first time that tail structures TTPA and TTPB have been demonstrated to serve as ligands that recognize the conserved Vibrio receptor Vp0980 to mediate phage adsorption.…”

“…TTPA forms the attachment site for the side fibres, while TTPB (also called a nozzle) serves as an adaptor for mounting additional functions [15,40,41]. Although TTPA and TTPB have been implicated as phage adhesins for adsorption to the host [42,43], it has not been shown whether they bind specific receptors to mediate the adsorption. We expressed GST-tagged TTPA and TTPB and performed pulldown assays with His-tagged Vp0980.…”

The Antibiofilm Activity of Dual-Function Tail Tubular Protein B from KP32 Phage

“…The diversity of phage PDs results from the co-evolution of phages and 52 their host bacteria [10]. Previously, we have reported the preliminary results of biological activity 53 of the tail tubular proteins A of the phages KP32 and KP34 [8,9]. These proteins were called the 54 dual-function proteins due to their structural and hydrolytic features related to binding and [11,5].…”

“…encoded in the open reading frames of phage structural proteins and thus were considered as 51 structural proteins [7][8][9]. The diversity of phage PDs results from the co-evolution of phages and 52 their host bacteria [10].…”

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“…For example, tail tubular protein A (TTPA), a structural tail protein of phage KP32, was shown to have additional polysaccharide depolymerase activity. Pyra et al (2017) cloned and expressed TTPA in E. coli and determined its enzymatic activity by agar spot tests on lawns of K. pneumoniae PCM2713, which produced translucent zones of reduced growth. Subsequent microscopic analysis of treated and untreated K. pneumoniae revealed cells treated with TTPA were stripped of their capsules.…”