PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of iaiPermissionsJournals.ASM.orgJournalIAI ArticleJournal InfoAuthorsReviewers
 
Infect Immun. 1991 August; 59(8): 2695–2705.
PMCID: PMC258075

Insertion element IS987 from Mycobacterium bovis BCG is located in a hot-spot integration region for insertion elements in Mycobacterium tuberculosis complex strains.

Abstract

Most strains of the Mycobacterium tuberculosis complex carry multiple copies of an IS3-like element, and these strains are highly polymorphic with regard to the site of integration in the chromosome. In contrast, Mycobacterium bovis BCG contains a single copy of the insertion element, and in all strains this copy is integrated at the same site in the chromosome. In this study, we determined the sequence of the single-copy insertion element from M. bovis BCG, IS987, and its flanking regions. The analysis of IS987 revealed that this element was virtually identical to the sequence of IS986 from M. tuberculosis. IS987 is located in a region containing direct repeats (DRs). The cloned flanking regions contained 20 virtually identical DRs of 36 bp, each separated by 35 to 41 bp of spacer DNA. Analysis of chromosomal DNA by the polymerase chain reaction revealed the presence of a cluster of 49 DRs, and IS987 is inserted in the 30th DR. Furthermore, the DR sequences were found to occur only in species of the M. tuberculosis complex and not in nine other mycobacterial species tested. Analysis of 14 M. tuberculosis strains revealed the presence of one insertion sequence element in the DR-containing region of eight strains, two insertion sequence elements were located in the DR region of five strains, and one strain did not contain an insertion sequence element in this region. Additionally, the DR-containing regions of these 14 M. tuberculosis strains were polymorphic in length and composition. We conclude that the DR cluster is a specific, hot-spot region for integration of insertion elements in the chromosome of M. tuberculosis complex strains.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (2.7M), or click on a page image below to browse page by page.

Images in this article


Articles from Infection and Immunity are provided here courtesy of American Society for Microbiology (ASM)