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Updated: Jul 9, 2025

Analysis of Group IV Viral SSHHPS Using In Vitro and In Silico Methods
Published on: December 21, 2019
A GH19 lysozyme and peptidase from Myoviridae cyanophages lacking the typical holin-endolysin system exhibit lytic
Li-Hui Meng1, Fei Ke2, Qi-Ya Zhang1
1Jiangsu Province Engineering Research Center for Marine Bio-resources Sustainable Utilization, College of Oceanography, Hohai University, Nanjing 210098, China; Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Abstract:
Most of the dsDNA cyanophages employ holin-endolysin lysis systems to damage the host cells. This study aimed to elucidate the lytic activity of ORF91 and ORF117 in the cyanophage MaMV-DH01, which lacked a conventional cholinesterase system. These two proteins contained Lyz-like superfamily domains and were annotated as a member of GH family 19 (named DHGH19) and peptidase (named DHpeptidase), respectively. Overexpression of DHGH19 in E. coli over a 5 h course demonstrated potent bactericidal activity, evident from significant growth inhibition, membrane damage, and leakage of intracellular enzymes of E. coli cells. However, the lytic activity of DHpeptidase was relatively weaker, exhibiting a bacteriostatic effect. It was important to highlight that the specific mutation of enzyme-catalyzed residues in DHGH19 (E122 and E131) showed that these were the essential amino acids for DHGH19 to exert its bactericidal activity. Furthermore, the lytic function of DHGH19 and DHpeptidase on cyanobacteria cells was confirmed by their overexpression in the cyanobacterium Synechocystis sp. PCC6803. Overall, this study provides novel insights into the lytic mechanism of Myoviridae cyanophage, offering potential alternatives for the development of GH19 and peptidase as new antibacterial agents in the future.
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