PMID:8057856

Citation	Decker, K, Krauel, V, Meesmann, A and Heller, KJ (1994) Lytic conversion of Escherichia coli by bacteriophage T5: blocking of the FhuA receptor protein by a lipoprotein expressed early during infection. Mol. Microbiol. 12:321-32
Abstract	The nucleotide sequence of the region between the oad gene, encoding the host specificity protein, and the right-terminal repetition of bacteriophage T5 DNA was determined. Five small open reading frames, the first of which was called llp, were detected, which apparently formed an operon transcribed from a promoter that overlapped the oad promoter. Both promoters were confirmed by primer extension assays. Using mRNA isolated at different times after T5 infection, the llp and oad promoters were identified as early and late promoters, respectively. The N-terminus of the llp gene product possess a signal sequence and a processing site characteristic of lipoproteins. After subcloning and expression of llp, its product Llp was identified as a 7.8 kDa polypeptide. Acylation of Llp was confirmed by addition of globomycin, which resulted in the accumulation of the unprocessed precursor form. FhuA+ cells synthesizing Llp were resistant to phage T5. Resistance was caused by inhibition of adsorption of T5 to its FhuA receptor protein. Resistance could be overcome by derepression of fhuA transcription, suggesting a blocking of FhuA by direct interaction with Llp. Since Llp-mediated T5 resistance has several aspects in common with the phenomenon of lysogenic conversion, we suggest that it should be called lytic conversion.
Links	PubMed
Keywords	Adsorption; Amino Acid Sequence; Bacterial Outer Membrane Proteins/antagonists & inhibitors; Bacteriolysis; Base Sequence; DNA, Bacterial/genetics; Escherichia coli/genetics; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Genes, Bacterial; Lipoproteins/genetics; Lipoproteins/physiology; Lysogeny; Molecular Sequence Data; Open Reading Frames; Promoter Regions, Genetic; Protein Processing, Post-Translational; Receptors, Virus/antagonists & inhibitors; Repetitive Sequences, Nucleic Acid; T-Phages/physiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BPT5:LLP		GO:0031225: anchored to membrane	ECO:0000314:		C		Fig. 7.	complete
BPT5:LLP		GO:0019085: early viral transcription	ECO:0000314:		P		Figure 8 shows the expression of T5 proteins during infection of E. coli F cells. All proteins were separated on a SDS-polyacrylamide gel and samples were analyzed at six time points. Llp was synthesized 5 minutes after infection and Llp showed the most expression at 10 minutes. In later time point, Llp was expressed less. This suggests that Llp was produced during early transcription.	complete CACAO 11868
BPT5:LLP		GO:1902735: negative regulation of receptor-mediated virion attachment to host cell	ECO:0000315:		P		The data from Table 2 suggested that Llp blocks the adsorption of phage T5 to the FhuA receptor protein on the host cell membrane. T5 adsorption was carried out for 10 minutes on medium plates at 37 deg C. T5 adsorption was measured by using standard cell and phage concentrations from another experiment. For JM101/(pVK3 – vector with no mutations and carries functional oad and llp genes), 82% of phages were not adsorbed to FhuA. For JM 101/(pVK3/IS1-2 – vector with an insertion downstream of oad and llp genes), 85% of phages were not adsorbed to FhuA. JM101/(pLG339 – vector with no llp gene), only 12% of phages were not adsorbed. This data suggests that llp blocks adsorption of T5 to FhuA.	complete CACAO 11869
BPT5:LLP		GO:0036406: anchored component of periplasmic side of cell outer membrane	ECO:0000314:		C		Figure 7B shows that globomycin inhibits the processing of lipoproteins which is shown as no expression of llp (no bands) at 20 ug/ml and 120 ug/ml. At 5 ug/ml globomycin, processing of lipoprotein still occurs but is still inhibited since there is still expression of precursor lipoprotein (p-Llp). With no globomycin, Llp is processed as shown with a band near the 8kDa marker but no expression at around 9 kDa. This suggests that Llp is a lipoprotein and must be processed in order to bind to the FhuA protein on the periplasmic side of the cell outer membrane.	complete CACAO 11870

References

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