The Core Oligosaccharide and Thioredoxin of Vibrio cholerae Are Necessary for Binding and Propagation of Its Typing Phage VP3

Abstract

VP3 is a T7-like phage and was used as one of the typing phages in a phage-biotyping scheme that has been used for the typing of Vibrio cholerae O1 biotype El Tor. Here, we studied the receptor and other host genes of V. cholerae necessary for the lytic propagation of VP3. Six mutants resistant to VP3 infection were obtained from the random transposon insertion mutant bank of the sensitive strain N16961. The genes VC0229 and VC0231, which belong to the wav gene cluster encoding the core oligosaccharide (OS) region of lipopolysaccharide, were found to be interrupted by the transposon in five mutants, and the sixth mutant had the transposon inserted between the genes rhlB and trxA, which encode the ATP-dependent RNA helicase RhlB and thioredoxin, respectively. Gene complementation, transcription analysis, and the loss of VP3 sensitivity by the gene deletion mutants confirmed the relationship between VP3 resistance and VC0229, VC0231, and trxA mutation. The product of VP3 gene 44 (gp44) was predicted to be a tail fiber protein. gp44 could bind to the sensitive wild-type strain and the trxA mutant, but not to VC0229 and VC0231 mutants. The results showed that OS is a VP3 receptor on the surface of N16961, thioredoxin of the host strain is involved in the propagation of the phage, and gp44 is the tail fiber protein of VP3. This revealed the first step in the infection mechanism of the T7-like phage VP3 in V. cholerae.Vibrio cholerae is the pathogenic agent of cholera and has caused seven pandemics. Only the O1 and O139 serogroups of V. cholerae have been associated with cholera epidemics, and strains of the O1 serogroup are subdivided into two biotypes, classical and El Tor (12). V. cholerae is the host for many bacteriophages, such as the tailed phage CP-T1 (18), K139 (39), and many filamentous phages (3,24,49). Phages infect and destroy host strains with high specificity, so phage-typing schemes were developed to differentiate strains of the same serogroups or genera in many bacteria, such as Salmonella enterica serovar Typhi (28) and Staphylococcus aureus (22). In V. cholerae, phage-typing schemes were also developed for typing of the O1 biotype El Tor (7) and O139 (5). A phagebiotyping scheme has been used for nearly 40 years in China for the typing of O1 El Tor strains (14). Based on the lytic patterns of the five typing phages, El Tor strains can be clustered into 32 phage types.The first step of phage infection is the specific binding of phages to receptors on the host cell surface, triggering the ejection of phage DNA into the cell and initiating the propagation process (1). Some outer membrane proteins serve as receptors for phage adsorption, such as LamB (19), OmpA (8),and OmpC (52) of Escherichia coli and OmpK of Vibrio parahaemolyticus (23). Lipopolysaccharide (LPS) is a common phage receptor. Cytotoxin-converting ⌽CTX from Pseudomonas aeruginosa (51) and FC3-10 from Klebsiella spp. (4) bind to the core region of LPS, while vibriophage CP-T1 (17) and ⌽YeO3-12, specific for Yersinia enterocolitica serotype...

Two Functional Type VI Secretion Systems in Avian Pathogenic Escherichia coli Are Involved in Different Pathogenic Pathways

“…Two T6SS-associated effectors, hemolysin-coregulated protein (Hcp) and valine-glycine repeat G (VgrG), function as exported chaperones of effectors (12,17) and have similar structures of the (gp27) 3 -(gp5) 3 spike complex (18,19). The tail fiber protein can bind to the receptor of sensitive bacteria specifically, which confers on bacteriophage a high degree of host specificity, and this mechanism may also be applied to the host cell recognition of the gp27 domain of VgrG (20,21). Some VgrG proteins have different C-terminal extensions, including certain domains with different activities.…”

Characterization of Pseudomonas aeruginosa Phage C11 and Identification of Host Genes Required for Virion Maturation

“…Similar studies on host-phage interactions have also been carried out in various systems, including Bacillus subtilis and phage SPP111, Yersinia pestis and phage L-413C12, Vibrio cholerae and phageVP313, V. cholerae biotype El Tor and phage VP414, and Salmonella enterica serovar Typhi and a number of diverse phages151617. All identified host genes required for phage infections approximately fall into two groups, one group of the genes related to the receptors syntheses, involving in phage recognitions and adsorptions; the other group of the genes involved in various pathways, possibly functioning in the stages of phage infection other than the adsorption.…”

The Resistance of Vibrio cholerae O1 El Tor Strains to the Typing Phage 919TP, a Member of K139 Phage Family

“…A Phage-Biotyping Scheme was developed for the subtyping of O1 El Tor strains and has been used in the cholera surveillance in China since the 1970s ( Gao et al, 1984 ; Xiao et al, 2013 ). In the phage typing part of the scheme, five typing phages (named VP1 to VP5, respectively; Gao et al, 1984 ; Zhang et al, 2009 ; Li et al, 2013 ; Xu et al, 2013 , 2014 ) are used and El Tor strains can be clustered into 32 distinct phage types (from 1 to 32) according to their lytic patterns to these five phages. In the biological typing part, El Tor strains can be grouped into 12 biotypes (from a to l) according to their biological performance in lysogenicity, susceptibility to temperate phage 919TP, sorbitol fermentation, and hemolysis ( Gao, 1988 ; Wang et al, 2009 ; Xiao et al, 2013 ).…”

“…The phenotype change from sensitivity to resistance to the phage infection always results from gene mutations. In our previous studies, we found that mutations in the receptor genes (e.g., ompW , core oligosaccharide genes, and O -antigen genes) of V. cholerae El Tor strains may render the strains resistant to the typing phages used in the Phage-Biotyping Scheme ( Zhang et al, 2009 ; Xu et al, 2013 , 2014 ). Bacteria commonly avoid phage infection using mechanisms associated with phage adsorption, injection, gene replication, assembly, and release ( Hyman and Abedon, 2010 ; Labrie et al, 2010 ).…”