1. The hetZ gene indirectly regulates heterocyst development at the level of pattern formation in Anabaena sp. strain PCC 7120
- Author
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Vaille Swenson, Benjamin Philmus, Patrick Videau, Michael O. Gaylor, Reid T. Oshiro, Orion S. Rivers, Blake Ushijima, Sasa K. Tom, and Loralyn M. Cozy
- Subjects
0301 basic medicine ,Anabaena ,Cellular differentiation ,Mutant ,Biology ,biology.organism_classification ,Microbiology ,Cell biology ,Complementation ,03 medical and health sciences ,Multicellular organism ,030104 developmental biology ,Gene expression ,Molecular Biology ,Gene ,Heterocyst - Abstract
Multicellular development requires the careful orchestration of gene expression to correctly create and position specialized cells. In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, nitrogen-fixing heterocysts are differentiated from vegetative cells in a reproducibly periodic and physiologically relevant pattern. While many genetic factors required for heterocyst development have been identified, the role of HetZ has remained unclear. Here, we present evidence to clarify the requirement of hetZ for heterocyst production and support a model where HetZ functions in the patterning stage of differentiation. We show that a clean, nonpolar deletion of hetZ fails to express the developmental genes hetR, patS, hetP and hetZ correctly and fails to produce heterocysts. Complementation and overexpression of hetZ in a hetP mutant revealed that hetZ was incapable of bypassing hetP, suggesting that it acts upstream of hetP. Complementation and overexpression of hetZ in a hetR mutant, however, demonstrated bypass of hetR, suggesting that it acts downstream of hetR and is capable of bypassing the need for hetR for differentiation irrespective of nitrogen status. Finally, protein-protein interactions were observed between HetZ and HetR, Alr2902 and HetZ itself. Collectively, this work suggests a regulatory role for HetZ in the patterning phase of cellular differentiation in Anabaena.
- Published
- 2018