P023
Identification of a novel structural component of the
outer membrane complex of the type IV pilus of
Neisseria gonorrhoeae
Katja Siewering1, Samta Jain1, Carmen Friedrich1,
Mariam T. Webber-Birungi2, Ina Binzen1,
Alexander Wagner1, Stuart Huntley1, Jörg Kahnt1,
Andreas Klingl3, Egbert Boekema2,
Lotte Søgaard-Andersen1 and Chris van der Does1
1
Max-Planck-Institut für Terrestrische Mikrobiologie,
Marburg, Germany
2
University of Groningen, Groningen, Netherlands
3
Philipps Universität Marburg, Marburg, Germany
The obligate human pathogen Neisseria gonorrhoeae colonizes
mucosal tissue in the urogenital tract causing the sexual transmitted
disease gonorrhea. To adhere to epithelial cells N.gonorrhoeae uses
type IV pili (T4P), which are also involved in twitching motility and
natural DNA transformation. The main outer membrane component of
this system is the secretin complex. Secretins form large oligomeric
ring like structures, forming the passage through the outer membrane,
and are found in e.g. Type II and Type III secretion systems and in
filamentous bacteriophages. It was shown that the secretin complex
of N.gonorrhoeae interacts with other proteins in the outer membrane
to form a large multi-domain complex, composed of a double ring
structure with extending spikes. Here we show the identification of a
novel structural component of the outer membrane complex of the T4P
of N.gonorrhoeae. Mass spectrometry analysis of outer membranes
was used to identify the conserved hypothetical protein NGFG_01788.
Bioinformatical data show that this protein is conserved among T4P
systems, indicating that NGFG_01788 might fulfill an important role
within the T4P systems. Deletion mutants of NGFG_01788 show loss
of the peripheral secretin ring and also a defect in T4P assembly.
Biochemical characterization of purified NGFG_01788 showed that
it binds to peptidoglycan via its LysM domain. Together, our data
show that TsaP forms an outer ring around the secretin complex and
attaches the secretin complex to the peptidoglycan layer.