Suppression of heterocyst differentiation in Anabaena PCC 7120 by a cosmid carrying wild-type genes encoding enzymes for fatty acid synthesis.
A cosmid containing a wild-type Anabaena PCC 7120 DNA fragment was found to suppress heterocyst differentiation, creating a Het phenotype in an otherwise wild-type strain. Curing of the cosmid restored the full wild-type Het+ Nif+ phenotype. The cosmid contains at least four genes encoding proteins with significant sequence similarity to enzymes involved in the synthesis of fatty acids. Selection for Nif+ revertants of the suppressed strain yielded modified cosmids, one of which contained a 10.2-kb transposon, Tas1, inserted into the promoter region of a gene encoding a protein with acyl carrier and beta-keto reductase domains. This gene, called hetN, was shown previously by Black and Wolk (J. Bacteriol. (1994) 176, 2282-2292) to inhibit heterocyst differentiation when present alone on a plasmid. Oddly, hetN gene transcription is detected later than 6 h into heterocyst differentiation.
Bauer
C C
CC
Department of Molecular Genetics and Cell Biology, University of Chicago, IL 60637, USA.
Ramaswamy
K S
KS
Endley
S
S
Scappino
L A
LA
Golden
J W
JW
Haselkorn
R
R
D017033:Anabaena / Q000166:cytology / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics; D002352:Carrier Proteins; D003360:Cosmids; D005227:Fatty Acids / Q000096:biosynthesis*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009024:Morphogenesis; D016254:Mutagenesis, Insertional; D016366:Open Reading Frames; D010088:Oxidoreductases; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D002352:Carrier Proteins; D005227:Fatty Acids; C107240:hetM protein, Anabaena; D010088:Oxidoreductases; C107239:HetN protein, Anabaena