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Cell‐type specificity of the Anabaena fdxN‐element rearrangement requires xisH and xisl
Author(s) -
Ramaswamy K. S.,
Carrasco Claudio D.,
Fatma Tasneem,
Golden James W.
Publication year - 1997
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 - 10.1046/j.1365-2958.1997.3081671.x
Subject(s) - biology , heterocyst , gene , recombinase , genetics , gene rearrangement , plasmid , dna , anabaena , promoter , microbiology and biotechnology , gene expression , recombination , bacteria , cyanobacteria
Summary The fdxN element, along with two other DNA elements, is excised from the chromosome during heterocyst differentiation in Anabaena sp. strain PCC 7120. Previous work showed that rearrangement of the fdxN element requires the xisF gene, which encodes a site‐specific recombinase, and suggested that at least one other heterocyst‐specific factor is involved. Here we report that the xisH and xisl genes are necessary for the heterocyst‐specific excision of the fdxN element. Deletion of a 3.2 kb region downstream of the xisF gene blocked the fdxN ‐element rearrangement in hetero‐cysts. The 3.2 kb deletion was complemented by the two overlapping genes xisH and xisl. Interestingly, extra copies of xlsHI on a replicating plasmid resulted in the xisF ‐dependent excision of the fdxN element in vegetative cells. Therefore, xisHI are involved in the control of cell‐type specificity of the fdxN rearrangement. The xisHI genes had no effect on the two other DNA rearrangements. The xisHl ‐induced excision of the fdxN element produced strains lacking the element and demonstrates that the 55 kb element contains no essential genes. xisH and xisl do not show similarity to any known genes.