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Sequence analysis and expression of the filamentous phage phi Lf gene I encoding a 48-kDa protein associated with
Abstract:
One viral strand of phi Lf, a filamentous phage of Xanthomonas campestris pv.campestris, the open reading frame (ORF440) behind gene VI was identified as gene I. This gene codes for pI protein (440 aa, 48 kDa) which was shown to be membrane-bound in the phi Lf-infected host cell by Western blot analysis using the antibody raised against the protein expressed in Escherichia coli. Its predicted amino acid sequence has a nucleotide-binding motif in the N-terminal 97 aa and a membrane-spanning domain (aa 221 to 236). These structural features are characteristic of pIs of several filamentous phages which are transmembrane proteins required for phage assembly. Thus far, nine phi Lf genes have been identified which are organized in the order GII-gX-gV-gVII-gIX-gVIII-gIII-gVI-gI, similar to the genome organization of E. coli filamentous phages.
Insights
Researchers identified gene I in the phi Lf phage, which infects Xanthomonas campestris. This gene codes for a membrane-bound pI protein crucial for phage assembly, similar to other filamentous phages.
Area of Science:
- Virology
- Molecular Biology
- Bacteriology
Background:
- Filamentous phages are viruses that infect bacteria.
- Xanthomonas campestris pv. campestris is a plant pathogen.
- Gene organization in phages is important for understanding viral replication.
Purpose of the Study:
- To identify and characterize gene I of the phi Lf filamentous phage.
- To determine the function and localization of the pI protein.
- To compare the genome organization of phi Lf with other filamentous phages.
Main Methods:
- Open reading frame (ORF) analysis to identify gene I.
- Protein expression in Escherichia coli and antibody generation.
- Western blot analysis to detect the pI protein in infected host cells.
- Bioinformatic analysis of the predicted amino acid sequence.
Main Results:
- Gene I was identified in phi Lf, located behind gene VI.
- The gene codes for a 440 amino acid, 48 kDa pI protein.
- The pI protein is membrane-bound in phi Lf-infected Xanthomonas campestris cells.
- The pI protein possesses a nucleotide-binding motif and a membrane-spanning domain.
- Nine phi Lf genes are organized similarly to E. coli filamentous phages.
Conclusions:
- The phi Lf pI protein is a transmembrane protein essential for phage assembly.
- Phi Lf shares conserved structural and organizational features with other filamentous phages.
- This study contributes to understanding the molecular mechanisms of filamentous phage infection and assembly.