Functional organization of the gene cluster involved in the synthesis of the pneumococcal capsule Authors Ernesto García Center for Biological Research, CSIC, Madrid, Spain Daniel Llull Center for Biological Research, CSIC, Madrid, Spain Rubens López Center for Biological Research, CSIC, Madrid, Spain Keywords: Streptococcus pneumoniae, Capsular polysaccharide, Virulence capsular switching, Natural transformation Abstract Streptococcus pneumoniae is a major human pathogen and its capsular polysaccharide has been shown to be the main virulence factor. The molecular organization of the genes governing the formation of this capsule was not studied until the 1990s. The capsular clusters (cap) of eight of the 90 known pneumococcal types have now been studied. The cap operon, located between the dexB and aliA genes, is arranged as a central region comprising the genes coding for the specifictype polysaccharide, flanked by open reading frames that are mostly common to all of the serotypes. The biochemical functions of 24 genes required for capsular polysaccharide biosynthesis have been elucidated but the precise role of the flanking regions in capsular formation is unknown. The natural genetic transformation characteristic of pneumococci, the arrangement of the cap locus and the abundance of transposable elements at this locus favor the genetic variability of the capsule in this microorganism. These well-documented observations together with the finding that some genes located outside the cap cluster may also participate in capsule formation increase the complexity of pneumococcal infection control. Downloads PDF Published 2010-03-16 Issue Vol. 2 No. 3 (1999) Section Review Articles License Submission of a manuscript to International Microbiology implies: that the work described has not been published before, including publication in the World Wide Web (except in the form of an Abstract or as part of a published lecture, review, or thesis); that it is not under consideration for publication elsewhere; that all the coauthors have agreed to its publication. The corresponding author signs for and accepts responsability for releasing this material and will act on behalf of any and all coauthors regarding the editorial review and publication process.If an article is accepted for publication in International Microbiology, the authors (or other copyright holder) must transfer to the journal the right–not exclusive–to reproduce and distribute the article including reprints, translations, photographic reproductions, microform, electronic form (offline, online) or any other reproductions of similar nature. Nevertheless, all article in International Microbiology will be available on the Internet to any reader at no cost. The journal allows users to freely download, copy, print, distribute, search, and link to the full text of any article, provided the authorship and source of the published article is cited. The copyright owner's consent does not include copying for new works, or resale. In these cases, the specific written permission of International Microbiology must first be obtained.Authors are requested to create a link to the published article on the journal's website. The link must be accompanied by the following text: "The original publication is available on LINK at <http://www.im.microbios.org>. Please use the appropiate URL for the article in LINK. Articles disseminated via LINK are indexed, abstracted, and referenced by many abstracting and information services, bibliographic networks, subscription agencies, library networks, and consortia.
