Shigatoxin, a toxin that causes the life-threatening illness Hemolytic Uremic Syndrome, can be produced by E. coli O157:H7. Bacteriophage, which are involved in the lysis of bacterial cells, start by adhering to the surface of the host cell using specific host cell surface receptors. The cytoplasm of the bacterial cell is where the bacteriophage’s genetic material is introduced. Omp A, a bacteriophage receptor binding protein (RBP) found in the tail end and receptors linked to adsorption, which correlates with the receptor’s structural design, initiates bacteriophage infection.

Bacteriophages must go through a number of mechanisms before they can begin the replication process, including (i) searching for and attaching (adsorption) to the surface receptors of the bacterial cell wall, and (ii) carefully perforating the bacterial cell membrane or wall and transferring viral DNA into the host cell cytoplasm. The tail RBP interacts specifically with one or more receptors on the bacterial cell wall during adsorption. RBP, which can be found in different tail substructures, is a significant predictor of bacteriophage host range.

The critical component of bacteriophage infection’s initial stage is at the matching tail/receptor, where it further opens the head-to-tail connector for DNA egress and enables the tail to construct a channel across the bacterial cell wall, which then channels the viral genome into the host cell. While mechanical piercing and/or the fusion of proteins with lipid components can be used to cross the bacterial cell wall’s membrane layers, the cell wall itself is more stiff and common. It is known that a number of virion proteins that are introduced into the bacterial cell wall include peptidoglycan-degrading activity to aid in cell wall crossing.

Although virionic lysine is frequently linked to specific parts or tail protein domains, it can also be a secreted protein from the capsid after viral opening. The tail sheath contracts as a result of irreversible attachment to the host receptor, allowing the inside of the tail tube to puncture the bacterial cell wall. Glycoprotein, one of the component proteins, exhibits muralitic action. Some bacteriophages enter the bacterial cell wall through the use of a mechanical tool, such as a syringe, which punctures the bacterial cell wall with its “needles”.

Bacteriophages utilise the enzymes in their tails without endangering the health of the cell. Contrarily, the Rz/Rz1 protein significantly damages the bacterial cell wall during the process for the release of progeny virions from infected bacteria, leading to the lysis of the host cell. The Rz/Rz1 protein, which is likewise a spanin complex made up of an integral cytoplasmic membrane protein and an outer membrane lipoprotein, The circular coil structure of Rz/Rz1 is given free energy to damage the bacterial cell membrane. Three irreversible successive processes can be seen as constituting bacteriophage-mediated Gram-negative lysis. The DNA from the bacteriophage’s head is released through the tail and into the cytoplasm of the bacterial cell during infection because bacteriophage particles bind to and recognize E. coli. Typically, a lytic cycle takes place, during which new bacteriophage particles are created inside the cell and DNA is duplicated. After that, the cell lyses, releasing its contents into the environment along with any formed virions. Additionally, Rz/Rz1 proteins all contribute to the destruction of cell membranes and the creation of holes in bacterial cell membranes.

This study was carried out between August 2020 and August 2021. Eight samples of bacteriophage from Surabaya’s ambient sewage and one isolate of E. coli O157:H7 encoded stx1 gene from prior study were used in the investigation. The ligand binding site of bacteriophages was investigated using mass spectrometry and NCBI Blast methods. DNA sequencing methods were used in conjunction with PCR to examine the rz/rz1 gene.

This study’s findings lead to the conclusion that the coverage of OmpA sequences as bacterial phage ligand binding sites ranged from 10% to 29%. The bacteriophage’s homology to the rz/rz1 bacteriophages gene in the NCBI database ranged from 96.97 to 98.89%. The study’s findings indicate that Rz/Rz1 contribute to host bacterial lysis, and OmpA functions as a bacteriophage receptor thanks to its peptide composition, which includes the ligand binding site. The OmpA and Rz/Rz1 lytic bacteriophages from Surabaya, Indonesia, show substantial changes in the amino acids Alanine, Aspartate, Glysine, Proline, and Serine (p = 0.011), Asparagine, Cysteine (p = 0.009), Isoleucine (p = 0.043), Lysine (p = 0.034), Methionine (p = 0.001), Threonine (p = 0.018), and Tryptophane (p = 0.007). It is hoped that the discovery of the RBP will lead to the creation of additional narrow-spectrum antibiotics.

Author(s) Details:

Tessa Sjahriani,
Department of Public Health and Department of Microbiology, Faculty of Medicine, Universitas Malahayati, Bandar Lampung, Lampung, Indonesia.

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Keywords: Narrow-spectrum antibiotics, OmpA, phage, Rz/Rz1, shigatoxin

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