Tat pathway-mediated translocation of the Sec pathway substrate OprM, an outer membrane subunit of the resistance nodulation division xenobiotic extrusion pumps, in Pseudomonas Aeruginosa.
BACKGROUND
Pseudomonas aeruginosa produces the Sec and Tat protein secretion machineries. The latter appears to be involved in the secretion of virulence factors, including phospholipase C (PlcH), and hence is a potential target of chemotherapeutic agents.


METHODS
The signal sequence of OprM, the outer membrane subunit of the xenobiotic extrusion pumps, was substituted with that of PlcH. The antibiotic susceptibility of oprM-deficient cells expressing the hybrid protein PlcH-OprM was evaluated using the agar dilution method.


RESULTS
The PlcH-OprM-expressing cells showed resistance to various MexAB-OprM substrate antibiotics. To evaluate the translocation route of PlcH-OprM, tatC encoding an indispensable component of the Tat machinery was knocked out in oprM-deficient cells. The tatC-oprM double mutant expressing PlcH-OprM exhibited antibiotic hypersusceptibility like the oprM-deficient cells, indicating that PlcH-OprM was translocated across the inner membrane exclusively through the Tat system.


CONCLUSIONS
This system can be used for the screening of Tat system inhibitors and will be an excellent model for the study of secretion and biogenesis of the β-barrel outer membrane proteins.
Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan.
K
K
Akiba
T
T
Ando
E
E
Isogai
T
T
Nakae
H
H
Yoneyama
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D024881:Drug Resistance, Bacterial / Q000187:drug effects; D026901:Membrane Transport Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D013379:Substrate Specificity; D015262:Xenobiotics / Q000378:metabolism / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; C402263:OprM protein, Pseudomonas aeruginosa; D000069816:SEC Translocation Channels; D015262:Xenobiotics; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins