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Nucleotide sequence and genetic complementation analysis of lep from Azotobacter vinelandii
1Department of Biological Sciences, Bowling Green State University, Ohio 43403, USA.
Abstract:
The lep of Azotobacter vinelandii is an 852-base-pair open reading frame (ORF) which encodes a protein of 284 amino acid residues. The translated protein shares 75% homology with leader peptidase I isolated from Pseudomonas fluorescens and 37% homology with leader peptidase I isolated from Escherichia coli. Five highly conserved regions found in the family of leader peptidase I proteins are conserved in A. vinelandii Lep. The putative membrane topology of the protein seems similar to that of E. coli leader peptidase I based on the hydrophobicity analysis of the predicted amino acid sequence. Southern blotting analysis of the A. vinelandii chromosome by probing with lep specific DNA revealed that lep is present as a single copy per the chromosome. A multicopy plasmid carrying A. vinelandii lep could complement a temperature sensitive lep mutant of E. coli strain IT41, suggesting that we have identified the functional copy of lep present on A. vinelandii genome.
Insights
Researchers identified the leader peptidase (lep) gene in Azotobacter vinelandii. This gene is crucial for bacterial protein processing and functions similarly to its counterparts in other bacteria.
Area of Science:
- Microbiology
- Molecular Biology
- Protein Biochemistry
Background:
- Leader peptidase (lep) is essential for processing secreted proteins in bacteria.
- Understanding the lep gene in Azotobacter vinelandii provides insights into bacterial protein secretion mechanisms.
Purpose of the Study:
- To identify and characterize the leader peptidase (lep) gene in Azotobacter vinelandii.
- To determine the genetic organization and functional conservation of A. vinelandii lep.
Main Methods:
- Sequence analysis of the Azotobacter vinelandii lep open reading frame (ORF).
- Homology comparisons with known leader peptidase I proteins from other bacterial species.
- Hydrophobicity analysis to predict membrane topology.
- Southern blotting to assess gene copy number.
- Functional complementation of an Escherichia coli lep mutant.
Main Results:
- The A. vinelandii lep gene is an 852-base-pair ORF encoding a 284-amino acid protein.
- The translated protein exhibits significant homology to leader peptidases from Pseudomonas fluorescens and Escherichia coli.
- Conserved regions characteristic of the leader peptidase I family are present in A. vinelandii Lep.
- Hydrophobicity analysis suggests a membrane topology similar to E. coli leader peptidase I.
- Southern blotting confirms lep is a single-copy gene in the A. vinelandii chromosome.
- A. vinelandii lep successfully complemented a temperature-sensitive E. coli lep mutant.
Conclusions:
- The functional copy of the leader peptidase gene has been identified in Azotobacter vinelandii.
- The A. vinelandii leader peptidase shares conserved structural and functional features with other bacterial leader peptidases.
- This finding contributes to the understanding of protein processing and secretion in Azotobacter vinelandii.