Analysis of Porphyromonas gingivalis PG27 by deletion and intragenic suppressor mutation analyses

作者：Ishiguro I; Saiki K^*; Konishi K

来源：Molecular Oral Microbiology, 2011, 26(5): 321-335.

DOI：10.1111/j.2041-1014.2011.00620.x

• gingipain
• lipopolysaccharide
• Porphyromonas
• secretion

PG27 is required for secretion of virulence factor gingipains, and has recently been proposed as LptO, which is involved in O-deacylation of lipopolysaccharide. In the present study, a predicted 14 anti-parallel beta-strand structure of PG27 was ascertained. Deletion study showed that the region from Asp382 to the C-terminal His391 of PG27 is dispensable for the function of PG27. Analysis of C-terminal deletion mutants revealed that the region in strand S14 (Asn369-Gly385) is important for activity. Of the gingipain-defective mutants, Delta Thr378-His391 and Delta Phe377-His391 produced amounts of PG27 comparable to those produced by wild-type cells, suggesting that Thr378-Phe381 contains essential residues for the function of PG27. In contrast, Delta Phe381-His391, Delta Ala380-His391, Delta Leu379-His391 and Delta Arg376-His391 produced no detectable PG27. The defects of the Delta Ala380-His391 mutant were suppressed by changing either Ala346 or Ala359 of PG27 to valine. Importantly, Ala346 and Ala359 are located close to Leu379 in the structural model of PG27. A359V compensated for the instability of PG27, but not the gingipain-defective phenotypes, of other deletion mutants tested, suggesting that Ala380 and Phe381 of PG27 are important for the stability of PG27. Lastly, we found that the C-terminal region of PG27 may be located in the periplasm. Taken together, these findings fit well with a predicted beta-barrel structure model for PG27, and show that strand S14 is important for its function.

• 出版日期2011-10