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Phosphate starvation affects the synthesis of outer membrane proteins in Thiobacillus ferrooxidans
C A Jerez1, M Seeger, A M Amaro
1Departamento de Bioquímica, Facultad de Medicina, Universidad de Chile, Santiago.
Abstract:
The outer membrane protein (omp40) component from the chemolithoautotrophic acidophilic Thiobacillus ferrooxidans is apparently regulated by the external pH and the concentration of phosphorus. Its amino-terminal sequence showed little identity with the Escherichia coli OmpC, OmpF or PhoE porins, but was 38.5% identical to the outer membrane channel-forming protein NosA from Pseudomonas stutzeri, whose expression is also regulated environmentally. In addition, the partial amino acid sequence of T. ferrooxidans omp40 showed between 34 and 38% identity with the amino-terminal end of the small outer membrane proteins Rck and PagC from Salmonella typhimurium and OmpX from Enterobacter cloacae.
Insights
The outer membrane protein (omp40) from Thiobacillus ferrooxidans is regulated by pH and phosphorus. Its sequence shows limited similarity to E. coli porins but shares identity with environmental proteins from other bacteria.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Thiobacillus ferrooxidans is a chemolithoautotrophic acidophile with a unique outer membrane.
- Outer membrane proteins play crucial roles in bacterial adaptation and interaction with the environment.
Purpose of the Study:
- To characterize the outer membrane protein (omp40) from Thiobacillus ferrooxidans.
- To investigate the regulation and sequence homology of omp40.
Main Methods:
- Amino-terminal sequencing of T. ferrooxidans omp40.
- Sequence comparison with known outer membrane proteins from various bacterial species.
Main Results:
- Omp40 expression is regulated by external pH and phosphorus concentration.
- Omp40 shows low sequence identity to E. coli porins (OmpC, OmpF, PhoE).
- Omp40 exhibits significant homology to NosA from Pseudomonas stutzeri and other small outer membrane proteins (Rck, PagC, OmpX).
Conclusions:
- T. ferrooxidans omp40 is an environmentally regulated outer membrane protein.
- Its sequence homology suggests a potential role in channel formation or environmental adaptation.
- Omp40 represents a novel class of bacterial outer membrane proteins.