A novel peptidoglycan‐linked lipoprotein (ComL) that functions in natural transformation competence of Neisseria gonorrhoeae

Abstract

A novel peptidoglycan-linked lipoprotein (ComL) has been identified which is required for efficient transformation of Neisseria gonorrhoeae by species-related DNA. Although most mutations in comL appear to be lethal, transposon shuttle mutagenesis was successful in generating a single viable comL mutant of N. gonorrhoeae strain MS11. This mutant, N457, exhibits a cratered and crinkled colony morphology and grows slower than wild-type MS11. However, as indicated by electron microscopy, this retardation is due to a small bacterial size rather than to a decreased generation time of the mutant bacteria. Complementation of N457 with an intact comL gene via the Hermes shuttle system fully reconstitutes bacterial size, colony morphology, and transformation competence of the wild-type strain. comL is a single-copy gene and maps downstream of the previously described comA gene. It is transcribed in the opposite direction, probably using the same transcriptional terminator. ComL has a predicted size of 29 kDa and is synthesized in Escherichia coli under the control of its native promoter, which is highly conserved with the E. coli promoter consensus sequence. The 5' end of the coding sequence reveals a lipoprotein secretion signal shown to be functional by gene fusion with alkaline phosphatase (phoA'). In E. coli, cloned ComL can be labelled with [3H]-palmitic acid, thus demonstrating its lipoproteinaceous nature. Palmitoylated ComL appears to be covalently bound to the murein sacculus of E. coli and N. gonorrhoeae since it resists boiling in 4% sodium dodecyl sulphate and is released only by lysozyme treatment. Homologous counterparts of the comL gene are found in Neisseria meningitidis as well as in several nonpathogenic Neisseria species.

Investigation of the role of the BAM complex and SurA chaperone in outer-membrane protein biogenesis and type III secretion system expression in Salmonella

“…Interestingly, we found that BamD was not essential in Salmonella, unlike its homologue in E. coli (Malinverni et al, 2006;Onufryk et al, 2005), and its homologue in Neisseria gonorrhoeae, in which total deletion of comL (the bamD homologue) failed (Fussenegger et al, 1996). This constitutes the main difference between the BAM complex of Salmonella and that of E. coli.…”

A Putatively Phase Variable Gene ( dca ) Required for Natural Competence in Neisseria gonorrhoeae but Not Neisseria meningitidis Is Located within the Division Cell Wall ( dcw ) Gene Cluster

“…In addition to the requirement for the expressions of pili (22,54), other proteins have been shown to have a role in natural transformation in the Neisseria spp. These include Tpc, mutants of which form tetracocci deficient in epithelial cell invasion and competence (23); ComA, an inner membrane protein which may be involved in translocation of DNA into the cytoplasm (19); ComL, a peptidoglycan-bound lipoprotein, mutants of which are significantly decreased in transformation (24); and PilT, which is involved in twitching motility and DNA uptake (63). Our results indicate that dca is also essential for transformation in gonococci.…”

Assembly of outer-membrane proteins in bacteria and mitochondria

“…However, even in the closely related bacterium Salmonella enterica, BamD appears to be dispensable (Fardini et al, 2009). Also, in Neisseria gonorrhoeae, a viable knockout mutant in the bamD homologue, designated comL, has been described (Fussenegger et al, 1996) but the gene appears essential for viability and OMP assembly in N. meningitidis (Volokhina et al, 2009). Thus, the Bam complex in bacteria consists of one essential central component, Omp85/BamA, and a variable number of accessory components, the importance of which is variable and depends on the specific component and the bacterium being studied.…”