Neisseria gonorrhoeae IgA protease. Secretion and implications for pathogenesis

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Pathogenesis

Background:

• Neisseria gonorrhoeae produces IgA protease, an enzyme crucial for its virulence.
• Understanding the genetic basis and secretion mechanism of IgA protease is essential for developing effective treatments.

Purpose of the Study:

• To clone and characterize the gene responsible for IgA protease production in N. gonorrhoeae.
• To investigate the processing and secretion of IgA protease and its associated proteins.

Main Methods:

• Gene cloning of a 5 kb DNA fragment from N. gonorrhoeae MS11 into E. coli.
• DNA sequencing to identify open reading frames.
• Analysis of protein processing and localization.

Main Results:

• A 5 kb DNA fragment conferred expression and excretion of IgA protease in E. coli.
• DNA sequencing revealed a 169 kd precursor protein.
• Autoproteolytic cleavage yielded mature IgA protease (106 kd), a soluble alpha-protein (15 kd), and a membrane-bound beta-protein (45 kd).
• Cleavage sites resemble those in IgA1, suggesting potential other substrates.

Conclusions:

• The cloned DNA fragment contains the gene for IgA protease and associated proteins.
• The processing and secretion pathway involves autoproteolytic cleavage.
• The alpha- and beta-proteins may contribute to gonococcal virulence.
• IgA protease might target other human proteins besides IgA1.