Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

Editor

Personal info

View

About

Terms

Javascript disabled

Please enable Javascript support in your browser to use this application.

Instructions on how to enable JavaScript on different browsers can be found here: http://www.google.com/support/bin/answer.py?answer=23852.

[edit this page]

Gene Review:

hetN - ketoacyl reductase

Nostoc sp. PCC 7120

Black, T.A. et al., Callahan, S.M. et al., Borthakur, P.B. et al., Li, B. et al., Khudyakov, I.Y. et al.

Callahan, Buikema,

Welcome! If you are familiar with the subject of this article, you can contribute to this open access knowledge base by deleting incorrect information, restructuring or completely rewriting any text. Read more.

Disease relevance of hetN

Summary In the filamentous cyanobacterium Anabaena sp. PCC 7120 patS and hetN suppress the differentiation of vegetative cells into nitrogen-fixing heterocysts to establish and maintain a pattern of single heterocysts separated by approximately 10 undifferentiated vegetative cells [1].

High impact information on hetN

Analysis of the S2-45 mutant revealed a R223W mutation in HetR, and reconstruction in the wild-type background showed that this mutation was responsible for the Mch phenotype and resistance not only to overexpressed patS, but also to overexpressed hetN, another negative regulator of differentiation [2].
Suppression of heterocyst formation by HetN appears to occur both upstream and downstream of the positive regulator HetR: overexpression of hetN in undifferentiated filaments prevents the wild-type pattern of hetR expression as well as the multiheterocyst phenotype normally observed when hetR is expressed from an inducible promoter [3].
The gene hetN encodes a putative oxidoreductase that is known to suppress heterocyst differentiation when present on a multicopy plasmid in Anabaena sp. PCC 7120 [3].
A third, 711-bp ORF (hetI) encoded on the opposite strand ends 42 bp away from the 3' end of hetN [4].
Sequence analysis around the site of insertion of the transposon showed that the insertion lies within the 5' end of an 861-bp open reading frame (ORF) (hetN) [4].

Biological context of hetN

The presence of hetN, as the only ORF, on a replicating plasmid suppresses heterocyst formation in wild-type cells, whereas the additional presence of hetI alleviates this effect [4].
Overexpression of hetN completely prevented hetR up-regulation under nitrogen-deprivation conditions, suggesting that its role in pattern control may depend on its inhibition of hetR expression [5].

Associations of hetN with chemical compounds

The product of translation of hetN (HetN) shows extensive similarity to NAD(P)H-dependent oxidoreductases that are involved in biosyntheses of fatty acids, poly-beta-hydroxybutyrate, nod factor, and polyketides [4].

Other interactions of hetN

Although differentiation proceeds unchecked in the absence of patS and hetN expression, differentiation is asynchronous and non-random [1].

Analytical, diagnostic and therapeutic context of hetN

An immunoblotting study showed that the hetN gene in Anabaena sp. PCC 7120 was expressed in vegetative cells grown with combined nitrogen [5].

References

Inactivation of patS and hetN causes lethal levels of heterocyst differentiation in the filamentous cyanobacterium Anabaena sp. PCC 7120. Borthakur, P.B., Orozco, C.C., Young-Robbins, S.S., Haselkorn, R., Callahan, S.M. Mol. Microbiol. (2005) [Pubmed]
Different functions of HetR, a master regulator of heterocyst differentiation in Anabaena sp. PCC 7120, can be separated by mutation. Khudyakov, I.Y., Golden, J.W. Proc. Natl. Acad. Sci. U.S.A. (2004) [Pubmed]
The role of HetN in maintenance of the heterocyst pattern in Anabaena sp. PCC 7120. Callahan, S.M., Buikema, W.J. Mol. Microbiol. (2001) [Pubmed]
Analysis of a Het- mutation in Anabaena sp. strain PCC 7120 implicates a secondary metabolite in the regulation of heterocyst spacing. Black, T.A., Wolk, C.P. J. Bacteriol. (1994) [Pubmed]
Expression of hetN during heterocyst differentiation and its inhibition of hetR up-regulation in the cyanobacterium Anabaena sp. PCC 7120. Li, B., Huang, X., Zhao, J. FEBS Lett. (2002) [Pubmed]

Contributions to this collaborative article are from individual authors of WikiGenes or mined by the WikiGenes Data Mining Engine from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenes Open Access Licence Privacy Policy Terms of Use apsburg

The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.