Skip to main content
Evidence-Based Supplement Research
Evidence-Based Supplement Research
Pillser
Search
Sign UpLog In

Evidence that the hanA gene coding for HU protein is essential for heterocyst differentiation in, and cyanophage A-4(L) sensitivity of, Anabaena sp. strain PCC 7120.

  • 1996-06
  • Journal of bacteriology 178(12)
    • I Khudyakov
    • C P Wolk

Study Design

Population
Anabaena sp. strain PCC 7120
Methods
Transposon-generated mutant AB22; reconstruction of the transposon mutation in the wild-type strain; sequencing of the flanking DNA; mapping of the transposon insertion by pulsed-field gel electrophoresis; complementation with a fragment of wild-type DNA bearing hanA
The highly pleiotropic, transposon-generated mutant AB22 of Anabaena sp. strain PCC 7120 exhibits slow growth, altered pigmentation, cellular fragility, resistance to phage A-4(L), and the inability to differentiate heterocysts. Reconstruction of the transposon mutation in the wild-type strain reproduced the phenotype of the original mutant. Sequencing of the flanking DNA showed that the transposon had inserted at the beginning of a gene, which we call hanA, that encodes Anabaena HU protein (R. Nagaraja and R. Haselkorn, Biochimie 76:1082-1089, 1994). Mapping of the transposon insertion by pulsed-field gel electrophoresis showed that hanA is located at ca. 4.76 Mb on the physical map of the chromosome and is transcribed clockwise. Repeated subculturing of AB22 resulted in improved growth and loss of filament fragmentation, presumably because of one or more compensatory mutations; however, the mutant retained its A-4(L)r Het- phenotype. The mutation in strain AB22 could be complemented by a fragment of wild-type DNA bearing hanA as its only open reading frame.

Research Insights

Back to top