HOMEPRODUCTSCOMPANYCONTACTFAQResearchDictionaryPharmaSign Up FREE or Login

Relationship between phase variation in colony morphology, intrastrain variation in cell wall physiology, and nasopharyngeal colonization by Streptococcus pneumoniae.

Abstract
Streptococcus pneumoniae undergoes phase variation in colony morphology, which has been implicated as a factor in the pathogenesis of pneumococcal disease. Phenotypic differences between opaque and transparent colony forms correlate with differences in rates of autolysis. This study examined whether differences in autolysis are caused by differences in expression of the major amidase, LytA, or the structure of its peptidoglycan substrate. No significant difference was detected by high-pressure liquid chromatography analysis of stem peptides released after treatment of purified peptidoglycan with amidase. Differences in the rate of digestion of purified cell walls, furthermore, did not correlate with susceptibility to autolysis. Lower levels of autolysis in opaque variants, however, was associated with decreased levels of immunodetectable LytA on colony immunoblots and Western blots (immunoblots). Diminished cell-surface-associated LytA in opaque variants was also demonstrated by whole-cell inhibition enzyme-linked immunosorbent assay. Since transparent variants have been shown both to colonize the nasopharynx more efficiently in an animal model and to express more surface-exposed LytA, it was determined whether LytA contributes to colonization in a neonatal rat model of pneumococcal carriage. Defined mutants in the lytA gene were used to show that there was no significant contribution by LytA to nasopharyngeal colonization in this model. Although the expression of LytA was shown to undergo phase variation in association with colony morphology, lytA mutants are still capable of phenotypic variation in colony morphology, which suggests that other factors are responsible for intrastrain differences which affect colonization.
AuthorsJ N Weiser, Z Markiewicz, E I Tuomanen, J H Wani
JournalInfection and immunity (Infect Immun) Vol. 64 Issue 6 Pg. 2240-5 (Jun 1996) ISSN: 0019-9567 [Print] United States
PMID8675333 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
Chemical References
  • Enzymes
  • Peptidoglycan
  • N-Acetylmuramoyl-L-alanine Amidase
Topics
  • Animals
  • Cell Wall (physiology)
  • Enzymes (analysis, physiology)
  • N-Acetylmuramoyl-L-alanine Amidase
  • Nasopharynx (microbiology)
  • Peptidoglycan (metabolism)
  • Rats
  • Streptococcus pneumoniae (physiology)

Join CureHunter, for free Research Interface BASIC access!

Take advantage of free CureHunter research engine access to explore the best drug and treatment options for any disease. Find out why thousands of doctors, pharma researchers and patient activists around the world use CureHunter every day.
Realize the full power of the drug-disease research graph!


Choose Username:
Email:
Password:
Verify Password:
Enter Code Shown: