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ATP-binding sites in the membrane components of histidine permease, a periplasmic transport system
Abstract:
Two components of the histidine permease in Salmonella typhimurium, the membrane-bound P and M proteins, react with the photoaffinity labeling reagent 8-azido-ATP in isolated membranes. The extent of labeling is decreased by the addition of ATP and somewhat less by addition of GTP, CTP, UTP, and ADP. Cyclic AMP, NAD, FAD, and S-adenosylmethionine have little effect. We propose that one or both of these proteins have a site capable of binding an adenine nucleotide and that, therefore, they may be involved in the energy-coupling step in active transport.
Insights
Researchers found that histidine permease proteins (P and M) in Salmonella typhimurium bind to ATP, suggesting a role in active transport energy coupling. This discovery sheds light on bacterial transport mechanisms.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- The histidine permease in Salmonella typhimurium is crucial for nutrient uptake.
- Understanding the energy-coupling mechanisms in active transport is vital for deciphering cellular processes.
Purpose of the Study:
- To investigate the interaction of histidine permease components with nucleotides.
- To explore the potential role of permease proteins in energy transduction during active transport.
Main Methods:
- Utilizing photoaffinity labeling with 8-azido-ATP on isolated bacterial membranes.
- Assessing the effect of various nucleotides (ATP, GTP, CTP, UTP, ADP) on protein labeling.
Main Results:
- The membrane-bound P and M proteins of the histidine permease were labeled by 8-azido-ATP.
- Labeling was significantly reduced by ATP and, to a lesser extent, by other adenine and guanine nucleotides.
- Other tested compounds like cyclic AMP, NAD, FAD, and S-adenosylmethionine showed minimal effect on labeling.
Conclusions:
- The P and M proteins of the histidine permease likely possess an adenine nucleotide-binding site.
- These findings suggest that the histidine permease may be involved in the energy-coupling step of active transport.