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spbA locus ensures the segregational stability of pTH1030, a novel type of Gram‐positive replicon
Author(s) -
Lereclus D.,
Arantes O.
Publication year - 1992
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1992.tb00835.x
Subject(s) - replicon , plasmid , biology , dna , genetics , dna replication , coding region , microbiology and biotechnology , locus (genetics) , plasmid preparation , origin of replication , gene , pbr322
Summary The replication region of the plasmid pHT1030 of Bacillus thuringiensis was previously mapped to a 2.9 kb DNA fragment. The DNA sequence was analysed and it was shown that the minimal replicon resides within a 1 kb fragment of DNA carrying no potential protein coding sequence. Moreover, no production of single‐stranded DNA intermediates was detected in the plasmid‐containing cells. pHT1030 therefore belongs to a class of replicons not previously described in Gram‐positive bacteria. Examination of the segregational stability of deletion derivatives of pHT1030 in bacilli defined two stability regions. One is located within the minimal replicon of pHT1030, whereas the second ( spbA ) is not required for replication. spbA encodes a 15 kDa protein and ensures the segregational stability of the plasmid. This effect of spbA is particularly highlighted in sporulation. The absence of the spbA locus gives rise to plasmid‐free spores at high frequency, whereas the spbA + plasmids are stably maintained. The stability of the plasmids during sporulation seems to be correlated with an unequal division of the cell by the sporulation septum.