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The penC mutation conferring antibiotic resistance in Neisseria gonorrhoeae arises from a mutation in the PilQ secretin that interferes with multimer stability
Author(s) -
Zhao Shuqing,
Tobiason Deborah M.,
Hu Mei,
Seifert H. Steven,
Nicholas Robert A.
Publication year - 2005
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2005.04752.x
Subject(s) - biology , mutation , microbiology and biotechnology , secretin family , pilus , missense mutation , neisseria gonorrhoeae , gene , genetics , escherichia coli , receptor , vasoactive intestinal peptide , neuropeptide
Summary The penC resistance gene was previously characterized in an FA19 penA mtrR penB gonococcal strain (PR100) as a spontaneous mutation that increased resistance to penicillin and tetracycline. We show here that antibiotic resistance mediated by penC is the result of a Glu‐666 to Lys missense mutation in the  pilQ   gene  that  interferes  with  the  formation  of the SDS‐resistant high‐molecular‐mass PilQ secretin complex, disrupts piliation and decreases transformation frequency by 50‐fold. Deletion of pilQ in PR100 confers the same level of antibiotic resistance as the penC mutation, but increased resistance was  observed  only  in  strains  containing  the  mtrR and penB resistance determinants. Site‐saturation mutagenesis of Glu‐666 revealed that only acidic or amidated amino acids at this position preserved PilQ function. Consistent with early studies suggesting the importance of cysteine residues for stability of the PilQ multimer, mutation of either of the two cysteine residues in FA19 PilQ led to a similar phenotype as penC : increased antibiotic resistance, loss of piliation, intermediate levels of transformation competence and absence of SDS‐resistant PilQ oligomers. These data show that a functional secretin complex can enhance the entry of antibiotics into the cell and suggest that the PilQ oligomer forms a pore in the outer membrane through which antibiotics diffuse into the periplasm.

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