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Role of an ABC importer in mycobacterial drug resistance
P K Chakraborti1, K Bhatt, S K Banerjee
1Institute of Microbial Technology, Chandigarh, India. pradip@koel.imtech.ernet.in
Abstract:
Phosphate specific transporter (Pst) in bacteria is involved in phosphate transport. Pst is a multisubunit system which belongs to the ABC family of transporters. The import function of this transporter is known to be operative at media phosphate concentrations below the millimolar range. However, we found amplification of this transporter in a laboratory generated ciprofloxacin resistant Mycobacterium smegmatis colony (CIPr) which was grown in a condition when phosphate scavenging function of this operon was inoperative. Our results therefore argue the role of this ABC importer in conferring high level of fluoroquinolone resistance in CIPr.
Insights
Amplification of the phosphate specific transporter (Pst) in Mycobacterium smegmatis correlated with high-level fluoroquinolone resistance. This suggests Pst may play a role in antibiotic resistance, independent of phosphate transport.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Physiology
Background:
- The phosphate specific transporter (Pst) is a bacterial ABC transporter system.
- Pst facilitates phosphate uptake, primarily at low phosphate concentrations.
Purpose of the Study:
- To investigate the role of the Pst system in antibiotic resistance.
- To determine if Pst amplification contributes to fluoroquinolone resistance in Mycobacterium smegmatis.
Main Methods:
- Generation of a laboratory ciprofloxacin-resistant Mycobacterium smegmatis colony (CIPr).
- Analysis of Pst transporter gene amplification in CIPr.
- Culturing bacteria under conditions where phosphate scavenging is inoperative.
Main Results:
- Observed amplification of the Pst transporter in a ciprofloxacin-resistant Mycobacterium smegmatis strain.
- This amplification occurred under conditions where the phosphate transport function of the operon was not active.
- The results suggest a link between Pst amplification and high-level fluoroquinolone resistance.
Conclusions:
- The phosphate specific transporter (Pst) system may contribute to high-level fluoroquinolone resistance in Mycobacterium smegmatis.
- Pst's role in resistance appears independent of its canonical phosphate import function.
- Further research is warranted to elucidate the mechanism of Pst in antibiotic resistance.