Nrc of Streptococcus pneumoniae suppresses capsule expression and enhances anti-phagocytosis.
Streptococcus pneumoniae is a major pathogen of community-acquired pneumonia and one of its major virulence factors is pneumolysin, which functions as a cholesterol-dependent cytolytic pore-forming toxin. In this study, we identified the ply-like gene spd0729 in a BLAST search. Unexpectedly, hemolytic and cytotoxic assays showed no significant differences between a Deltaspd0729 mutant strain and the wild-type strain, whereas the mutant strain exhibited weaker anti-phagocytic activity in human peripheral blood. In addition, real-time RT-PCR analysis revealed that four capsular biosynthesis genes in the mutant strain had expressions 7- to 432-fold greater than those of the wild type, while an enzyme-linked immunoassay showed a mean 3-fold greater amount of total capsular polysaccharide in the mutant strain. These results suggest that Spd0729 is not a cytolysin, though it plays crucial roles in anti-phagocytosis and regulation of capsule expression. Thus, we named Spd0729 as a negative regulator of capsular polysaccharide synthesis (Nrc).
Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
Masaya
M
Yamaguchi
Yuki
Y
Minamide
Yutaka
Y
Terao
Ryutaro
R
Isoda
Taiji
T
Ogawa
Shin-ichi
S
Yokota
Shigeyuki
S
Hamada
Shigetada
S
Kawabata
D000595:Amino Acid Sequence; D016667:Bacterial Capsules / Q000096:biosynthesis* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D010587:Phagocytosis; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000472:pathogenicity*
D001426:Bacterial Proteins