PMID:16484191

Citation	Orozco, CC, Risser, DD and Callahan, SM (2006) Epistasis analysis of four genes from Anabaena sp. strain PCC 7120 suggests a connection between PatA and PatS in heterocyst pattern formation. J. Bacteriol. 188:1808-16
Abstract	The hetR, patA, hetN, and patS genes are part of a regulatory network that regulates the differentiation and patterning of heterocysts in the filamentous cyanobacterium Anabaena sp. strain PCC 7120. In this report, the epistatic interactions of mutant alleles of these four genes have been used to refine our understanding of their relationships to one another. The hetR gene was necessary for differentiation in genetic backgrounds that normally give rise to excessive differentiation, supporting its role as the master regulator of differentiation and indicating that HetR directly regulates factors in addition to hetR and patS genes that regulate differentiation. A functional patS gene was necessary for the delayed multiple-contiguous-heterocyst phenotype observed in hetN mutants as well as for the relative lack of intercalary heterocysts in patA mutants. Epistasis results with mutant alleles of these three genes suggested that PatA attenuates the negative effects of both PatS and HetN on differentiation and promotes differentiation independent of its antagonistic effects on PatS and HetN activity. Cooverxpression of patS and hetR in a synthetic operon indicated that patS acts at a point downstream of hetR transcription in the regulatory network controlling differentiation. A model for the regulation of differentiation that is consistent with these and previous findings is presented.
Links	PubMed PMC1426565 Online version:10.1128/JB.188.5.1808-1816.2006
Keywords	Alleles; Anabaena/genetics; Anabaena/physiology; Bacterial Proteins/genetics; Epistasis, Genetic; Gene Expression Regulation, Bacterial; Mutation; Oxidoreductases/genetics; Transcription, Genetic/physiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
NOSS1:PATA		GO:0043158: heterocyst differentiation	ECO:0000315: mutant phenotype evidence used in manual assertion		P		FIG. 1. Phenotypes of single mutant strains 48 h postinduction. PCC 7120 (A), hetR mutant strain UHM103 (B), patA mutant strain UHM101 (C), patS mutant strain UHM114 (D), hetN mutant strain 7120PN (E).	complete
NOSS1:PATA		GO:0031555: transcriptional attenuation	ECO:0000316: genetic interaction evidence used in manual assertion	UniProtKB:O52748	P		Figure 4: Heterocyst formation in patA pat S double mutant	complete
NOSS1:HETR		GO:0043158: heterocyst differentiation	ECO:0000315:		P		Figure 1 shows heterocyst formation in several mutant phenotypes, including a mutant for hetR.	complete
NOSS1:PATS		GO:0043158: heterocyst differentiation	ECO:0000315:		P		Figure 1: phenotypes of single mutant strains, including patA, patS, hetN, and hetR	complete
NOSS1:HETN		GO:0043158: heterocyst differentiation	ECO:0000315:		P		Figure 1: Phenotypes of single mutant strains, including mutants of patA, patS, hetR, and hetN	complete

References

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